The effects of vasopressin infusion on hepatic haemodynamics in an experimental model of liver metastases

Vasoactive drugs have a variety of effects upon splanchnic and hepatic haemodynamics which may alter tumour blood flow and potentiate the delivery of a chemotherapeutic drug to hepatic tumour. We have investigated the effects of vasopressin infusion on hepatic tumour blood flow in an experimental model of liver tumour. Hepatic tumour was induced by the intraportal inoculation of HSN sarcoma cells. Hepatic and splanchnic blood flow was determined using a dual reference microsphere technique before and after an intravenous infusion of vasopressin at a dose of 0.1 mU kg-1 min-1 for 10 min. There was a significant increase in systemic arterial blood pressure associated with a rise in portal venous inflow (P less than 0.01, Wilcoxen Signed rank Test) and a significant fall in hepatic arterial flow (P less than 0.05). The tumour: liver blood flow ratio was significantly increased by vasopressin infusion (P less than 0.02). Vasopressin infusion decreases hepatic arterial flow and increases tumour blood flow which may potentiate the delivery of a regionally delivered chemotherapeutic drug to hepatic tumour.     

Effect of continuous regional vasoactive agent infusion on liver metastasis blood flow.

Regionally administered vasopressors might increase tumour chemotherapy uptake by differentially constricting normal and tumour blood vessels, leading to a selective increase in blood flow to the tumour. In this study, we compared the effects of the vasopressors angiotensin II, vasopressin and endothelin I and the vasodilator calcitonin gene-related peptide (CGRP) by continuously measuring liver parenchymal and tumour blood flow during a 30-min regional vasoactive infusion in a rat HSN liver metastasis model. Vasopressin and angiotensin II produced a vasoconstriction that decreased despite continued infusion, while endothelin I infusion led to prolonged vasoconstriction with a more gradual onset. CGRP infusion resulted in increased vessel conductance but a reduction in blood flow due to systemic hypotension. The tumour to normal flow ratio (TNR) was transiently increased during infusion of all pressors, but only endothelin I produced sufficient change to result in a rise in average TNR throughout pressor infusion. Continuous liver and tumour blood flow measurement throughout vasoactive infusion demonstrated that the extent and the duration of blood flow change varied with the agents assessed. No vasoactive agent increased tumour blood flow, but endothelin I had the most suitable vasoactive properties for enhancing tumour uptake of continuously infused chemotherapy.     

Continuous angiotensin II infusion increases tumour: normal blood flow ratio in colo-rectal liver metastases.

Insufficient blood flow within colo-rectal hepatic metastases is a factor which may limit drug delivery to, and thus the response of, these tumours to regional chemotherapy. Loco-regional flow may be manipulated pharmacologically to enhance the tumour blood flow relative to that of the normal liver. However, as yet, only transient effects have been studied. Patients receiving regional chemotherapy for unresectable hepatic disease were given a 45 min regional infusion of the vasoconstrictor Angiotensin II. Intrahepatic blood flow distribution was assessed serially by Positron Emission Tomography (PET) imaging together with the trapping tracer copper(II) pyruvaldehyde bis(N-4-methylthiosemicarbazone) (Cu-PTSM) labelled using copper-62. Eleven lesions in nine patients were studied, with no adverse effects. Prior to Angiotensin II administration tumour blood flow was generally found to be greater than that of liver (10/11 lesions; 8/9 patients; median TNR 1.3, iqr 0.9-2.5). A significant increase in relative flow to tumour was seen in response to 10 min Angiotensin II infusion in most cases (7/11 lesions; 7/9 patients; median TNR 2.1, iqr 1.4-4.1; P = 0.008), which appeared to be sustained throughout the 45 min infusion period (median TNR 1.85, iqr 1.3-3.8; P = 0.03). These effects were accompanied by transient elevation of mean arterial pressure, but no change in pulse rate. These observations suggest that prolonged regional vasoconstrictor administration could prove useful in the management of unresectable colo-rectal hepatic metastases, and that further development of vascular manipulation to enhance tumour targeting and drug delivery is warranted.     

The effects of sandostatin (Octreotide, SMS 201-995) infusion on splanchnic and hepatic blood flow in an experimental model of hepatic metastases.

Manipulation of hepatic blood flow may improve drug delivery to hepatic tumour. Somatostatin and its long acting analogues are known to elicit effects upon hepatic and splanchnic blood flow in experimental animals and patients with portal hypertension. This study investigates the effects of SMS 201-995 (sandostatin) infusion on hepatic, splanchnic and tumour blood flow in an experimental model of liver metastases. Hepatic tumour was induced by the intraportal inoculation of 10(6) HSN sarcoma cells and blood flow measured using the dual reference microsphere method before and after infusion of SMS 201-995. There was a significant decrease in hepatic arterial flow and a significant increase in the tumour:liver blood flow ratio associated with a marked reduction in blood flow to normal hepatic parenchyma. Portal venous inflow and tumour blood flow were not significantly affected. SMS 201-995 infusion may lead to preferential delivery of concomitantly injected cytotoxic drugs to hepatic tumour. In addition, the reduction in growth of hepatic tumour may be due to a reduction in nutritive, arterial blood flow to hepatic tumour.     

The effect of vasopressin and hepatic artery ligation on the blood supply to normal and metastatic liver tissue

The effect of low (0.08 microU g-1 body wt min-1) and high (0.16 microU g-1 body wt min-1) rates of vasopressin infusion on blood flow to normal liver tissue and to liver metastases derived from azoxymethane induced colorectal carcinomas was studied in 36 male Wistar rats. Portal venous flow was measured by electromagnetic flowmetry and blood flow to normal and metastatic liver tissue by the clearance of xenon-133 injected directly into the liver parenchyma or metastasis. The low rate of vasopressin infusion decreased portal venous flow but increased blood flow to normal and metastatic liver tissue while at the higher rate of infusion these effects were reversed. Hepatic artery ligation (HAL) immediately following a low rate of vasopressin infusion abolished the observed increase in blood flow to both normal liver tissue and metastases. HAL immediately following the higher rate of vasopressin infusion further reduced blood flow to metastases but did not further alter blood flow to normal liver tissue. HAL prior to the infusion of the vasoactive drug significantly reduced blood flow to metastatic liver tissue, increased portal venous flow and was without effect on blood flow to normal liver tissue. Following HAL, blood flow to metastatic liver tissue was not further altered by either the low or high rates of vasopressin infusion. However, blood flow to normal liver tissue after HAL was reduced by a low rate of infusion of vasopressin and increased by the higher rate of infusion. The results of this study indicate that blood flow to normal or metastatic liver tissue can be increased or decreased by differential rates of infusion of vasopressin. These observations may have important implications in the treatment of liver metastases in man where different rates of vasopressin infusion may potentiate the effects of hepatic artery ligation or cytotoxic therapy.     

Changes in hepatic blood flow during regional hyperthermia

The influence of liver hyperthermia on hepatic arterial and portal venous blood flow to tumour and normal hepatic tissue was examined in a rabbit VX2 tumour model. Hyperthermia was delivered by 2450 MHz microwave generator to exteriorized livers in 18 rabbits. Blood flow was measured in both portal vein and hepatic artery using radioactive tracer microspheres before, during and 5 min after intense (greater than 43 degrees C) hyperthermia. During hyperthermia a decrease in total liver blood flow was composed primarily of a decrease in hepatic arterial blood flow to tumour tissue. Tumours were supplied almost exclusively by the hepatic artery and thus total tumour blood flow was significantly depressed during heating. The decreased tumour blood flow persisted after the cessation of hyperthermia and was indicative of vascular collapse in the tumour tissue. Temperature differentials in tumour compared to normal tissue ranged from 5 degrees C to 8 degrees C during hyperthermia because of the lower tumour blood flow. The portal vein exerted minimal influence on temperatures attained in the tumour tissue during hyperthermia but would have mediated normal liver tissue heat loss.     

Duplex/colour Doppler sonography: measurement of changes in hepatic arterial haemodynamics following intra-arterial angiotensin II infusion.

Angiotensin II (AT-II) has been used to target regionally-administered cytotoxic microspheres in patients with intrahepatic tumours. The optimisation of vasoconstrictor targeting requires a knowledge of the blood flow changes induced by agents such as AT-II. We therefore assessed duplex/colour Doppler sonography (DCDS) as a means of evaluating the effects of AT-II infusion on hepatic arterial blood flow (HABF) and arterial resistance in patients with intrahepatic tumours. HABF was measured continuously in nine patients using DCDS before, during and after an infusion of AT-II (15 micrograms in 3 ml of saline over 90 s) via a hepatic artery catheter. In seven patients with less than 30% hepatic replacement by tumour, the baseline level of HABF was 331 +/- 85 ml min-1 (mean +/- s.d.), and this was reduced by 75-80% within 30 s of the start of AT-II infusion. HABF recovered rapidly from the end of the infusion, and increased by up to 20% above the baseline for approximately 2 min. In two patients with greater than 50% hepatic replacement, HABF showed no reduction but rose continuously from the start of AT-II infusion, increasing by a factor of 2-2.5 after 3-4 min. Arterial resistance showed reciprocal changes in all cases. We conclude that DCDS is effective in assessing the temporal changes in hepatic arterial blood flow caused by AT-II. In order to optimise tumour targeting, the injection of microspheres loaded with cytotoxic drugs should be completed before the end of the AT-II infusion. The targeting advantage of AT-II in patients with a high percentage hepatic replacement by tumour should be re-assessed.     

Changes in hepatic blood flow during regional hyperthermia

The influence of liver hyperthermia on hepatic arterial and portal venous blood flow to tumour and normal hepatic tissue was examined in a rabbit VX2 tumour model. Hyperthermia was delivered by 2450 MHz microwave generator to exteriorized livers in 18 rabbits. Blood flow was measured in both portal vein and hepatic artery using radioactive tracer microspheres before, during and 5 min after intense (>43°C) hyperthermia. During hyperthermia a decrease in total liver blood flow was composed primarily of a decrease in hepatic arterial blood flow to tumour tissue. Tumours were supplied almost exclusively by the hepatic artery and thus total tumour blood flow was significantly depressed during heating. The decreased tumour blood flow persisted after the cessation of hyperthermia and was indicative of vascular collapse in the tumour tissue. Temperature differentials in tumour compared to normal tissue ranged from 5°C to 8°C during hyperthermia because of the lower tumour blood flow. The portal vein exerted minimal influence on temperatures attained in the tumour tissue during hyperthermia but would have mediated normal liver tissue heat loss.     

Is there a relationship between regional microsphere distribution and hepatic arterial blood flow?

The relationship between hepatic arterial albumin microsphere distribution and hepatic arterial blood flow and the effects of regional angiotensin II were studied in a rat liver metastases model. Hooded-Lister rats were inoculated subcapsularly with 2 x 10(6) HSN sarcoma cells. At 20 days, hepatic arterial blood flow was measured using the reference microsphere technique. Animals then randomly received 50 microliters hepatic arterial saline or albumin microspheres (40 microns, 20 mg ml-1). Hepatic arterial blood flow measurements were then repeated at 5 min. After 5 min, animals were killed and tissues were weighed and counted in a gamma well counter. There were no significant differences between the hepatic blood flow measurements recorded before and after the control hepatic arterial saline infusion. However, regional albumin microspheres produced a significant reduction in tumour and normal liver blood flow and an 80% reduction in mean T/N blood flow ratio. Regional albumin microspheres were delivered to tumour in greater proportions (mean T/N ratio 3.89, SE 0.49) than would be expected from baseline hepatic arterial blood flow (mean T/N ratio 1.28, SE 0.22. P = 0.006). There was no correlation between T/N for baseline blood flow and albumin microsphere distribution.     

The Influence of Nitric Oxide on Tumour Vascular Tone

Acetylcholine and sodium nitroprusside, which vasodilate via release of NO by endothelium-dependent and endothelium-independent mechanisms respectively, had little effect on tumour vascular resistance when administered to tissue-isolated tumours perfused in their normal state. However, under phenylephrine-induced vasoconstriction, sodium nitroprusside induced vasodilation whilst acetylcholine induced a small vasoconstriction. Phenylephrine itself induced an oscillatory change in tumour perfusion pressure. The nitric oxide synthase (NOS) inhibitor N^Ω-nitro-L-arginine (L-NNA) caused a dose-dependent increase in vascular resistance in ex vivo perfused tumours which was greater than that in normal perfused hindlimbs. Systemic administration of L-NNA caused a 50% decrease in tumour blood flow which was a larger effect than in any of the normal tissues studied except spleen and skeletal muscle. Modification of NOS activity in tumours is a promising means for selective tumour blood flow modification. Investigation of endothelium-dependent versus endothelium-independent methods for modifying tumour blood flow may provide methods for further selectivity.     

Steady-state nonlinear pharmacokinetics of 5-fluorouracil during hepatic arterial and intravenous infusions in cancer patients

Hepatic arterial catheters were placed for therapy in 8 patients with primary or metastatic liver cancer. Temporary hepatic venous catheters allowed direct sampling of blood for hepatic venous drug concentrations. Patients were administered from three to six infusions at rates of 10, 30, 90, 135, 180, 210, and 270 mg/kg/day (0.053 to 1.43 microM/kg/min), given over 2 h, of 5-fluorouracil (FUra). In Method 1, FUra was infused i.v., and FUra was measured in plasma from hepatic arterial and hepatic venous blood. In Method 2, FUra was given i.v. at one time and infused into hepatic arterial blood at another time, and FUra was measured in plasma from peripheral blood at the same site in both cases. Steady-state FUra plasma concentrations were measured by a sensitive and specific high-performance liquid chromatography method. Data were computer fitted to the equations appropriate for a physiological two-compartment flow model with Michaelis-Menten elimination from the peripheral compartment and blood flow rate, Q, between the central and peripheral compartment. Methods 1 and 2 gave mean Vmax and Km values which did not differ significantly; the overall mean Vmax was 2.02 microM/kg/min, and the overall mean Km was 10.9 microM. For Method 1 the mean Q1 value was 0.0803 liters/(kg X min) or 5.26 liters/min, which is the same as cardiac output, but for Method 2 the mean Q2 value was higher, namely 0.189 liters/(kg X min) or 13.0 liters/min. Steady-state systemic and intrinsic clearances and extraction ratios decreased progressively as the dose rate increased. Intra- and inter-subject variation of both Vmax and Km were of the same order of magnitude. As a result, dose rate escalation should be conservative for dose rates above 135 mg/kg/day. The results support hepatic arterial infusion as a means of improving the therapeutic index of FUra in the treatment of cancer of the liver.     

The use of angiotensin II as a potential method of targeting cytotoxic microspheres in patients with intrahepatic tumour

Cytotoxic microspheres have been developed for intra-arterial use in patients with liver metastases. Following injection, the distribution of microspheres reflects the pattern of hepatic arterial blood-flow. Vasoactive agents, such as angiotensin II, by producing vasoconstriction in normal liver, might divert arterial blood toward tumour and thereby enhance the delivery of drug-loaded particles. Using a double isotope technique, the distribution of radiolabelled microspheres to tumour and normal liver tissue was measured before and after angiotensin II infusion in nine patients with multiple liver metastases. The median increase in tumour: normal ratio following angiotensin II infusion was by a factor of 2.8 (range 0.8-11.7, P less than 0.05). This novel approach to regional chemotherapy, using a combination of angiotensin II infusion and cytotoxic microspheres, increases the exposure of tumour to cytotoxic agents and may, therefore, enhance tumour response rates.     

Changes in hepatic haemodynamics in rats with overt liver tumour.

Overt liver tumour was induced in Fisher rats by intraportal administration of 1.6 x 10(7) Walker carcinosarcoma cells. Control groups of rats received similar volumes of dead cells or saline intraportally. All animals were studied at 3 weeks when overt tumour was present. The Hepatic Perfusion Index (HPI) was significantly raised in rats with overt tumour compared to both groups of control animals. Portal flow and portal venous inflow were significantly reduced in the presence of overt tumour but hepatic arterial flow did not alter. These observations suggest that the alteration in the HPI in the presence of overt tumour results from an alteration in portal venous flow and inflow even though the blood supply to the tumour is principally derived from the hepatic artery. The changes in hepatic haemodynamics in the presence of tumour were accompanied by a reduction in portal pressure, an increase in splanchnic vascular resistance and an increase in the degree of arteriovenous shunting through the liver. Portal vascular resistance was unchanged. These findings indicate that the presence of overt hepatic tumour results in gross derangements of hepatic blood flow. These changes must be taken into consideration when attempting to potentiate the delivery of cytotoxic drugs to hepatic tumour by manipulation of hepatic haemodynamics.     

Monitoring blood flow to colorectal liver metastases using laser Doppler flowmetry: the effect of angiotensin II.

Many colorectal liver metastases are hypovascular, and their low level of perfusion is associated with limited drug uptake and poor response rates with regional chemotherapy. We have previously shown that hepatic arterial vasoconstrictors may increase drug delivery to liver tumours, but the underlying haemodynamic changes have not been defined. Using intraoperative laser Doppler flowmetry (LDF) we have assessed the effect of intraarterial angiotensin II (AI) on tumour blood flow in ten patients with colorectal liver metastases. Measurements were performed during placement of infusion catheters for regional chemotherapy. Blood flow was recorded continuously with a Periflux PF3 perfusion monitor via a probe held on the tumour surface, following hepatic arterial infusion of 15 micrograms AII over 90 s. Six patients with isolated small metastases (< 5 cm in diameter) showed increases in flow, which reached a peak at 170-240 s from the start of AII infusion, and which were closely correlated with the corresponding increase in arterial pressure (r = 0.92, P = 0.009). Of the four patients with large confluent tumour deposits, two showed smaller transient increases in flow over the first 60 s of AII infusion and two had no measurable flow response. Increased blood flow following AII infusion may increase the exposure of tumour to therapeutic agents. This study suggests that both tumour size and the effect upon systemic arterial pressure may be important determinants of the blood flow response to AII. LDF may provide useful information about the potential of AII and other vasoconstrictors to enhance targeting precision.     

Characterisation of systemic dissemination of nonreplicating adenoviral vectors from tumours in local gene delivery

Systemic virus dissemination is a potential problem during local gene delivery in solid tumours. However, the kinetics and pathways of the dissemination have not been well characterised during the first 24 h after the infusion is started. To this end, we infused adenoviral vectors for luciferase or enhanced green fluorescence protein into three different tumour models in mice. During and/or after the infusion, we determined the amount of adenoviruses in the tumour, blood, and liver, and examined the transgene expression in the liver, lung, blood, and tumour. In addition, we intravenously injected tumour cells expressing luciferase and examined the biodistribution of these cells in the body. We observed transgene expression in the liver and tumour at 24 h after the infusion, but could not detect transgene expression in the blood and lung. The peak concentration of viral vectors in the plasma occurred during the intratumoral infusion. At 10 min after the infusion, few viral vectors remained in the blood and the ratio of copy numbers of adenoviruses between liver and tumour was > 2 in 80% and > or = 10 in 40% of the mice. Most tumour cells injected intravenously accumulated in the lung within the first 24 h. Taken together, these data indicated that systemic virus dissemination occurred mainly during the first 10 min after the intratumoral infusion was started, and that the dissemination was due to infusion-induced convective transport of viral vectors into leaky tumour microvessels.     

Effects of diethylamine/nitric oxide on blood perfusion and oxygenation in the R3230Ac mammary carcinoma.

The effects of intravenous diethylamine/nitric oxide (DEA/NO), a short-acting nitric oxide (NO) donor, on systemic haemodynamics, muscle and tumour blood flow (MBF and TBF) and tumour oxygenation were examined in rats bearing subcutaneous R3230Ac carcinoma in the leg. The effects of DEA/NO on the diameters of tumour-feeding and normal arterioles were evaluated in window chambers with and without implanted tumours. DEA/NO reduced mean arterial pressure (MAP) when given at doses > or = 100 nmol kg(-1), with maximal suppression at 0.5-1 min followed by return to baseline within 20 min. DEA/NO did not affect MBF except at the highest doses (500 and 1000 nmol kg(-1)). In contrast, DEA/NO reduced TBF and constricted tumour arterioles at doses > or = 100 nmol kg(-1). Tumour arteriolar vasomotion occurred in more than half the animals during hypotension and with a significantly higher frequency than in normal granulating tissue at a dose of 500 nmol kg(-1). Normal arterioles rapidly and significantly vasodilated for about 3 min and then returned to baseline. The reductions in TBF and MAP were accompanied by synchronous reduction in tumour pO2. Our findings suggest that DEA/NO decreases TBF in two ways. In the window chamber model, vascular steal occurs as normal arterioles adjacent to tumour dilate more than tumour arterioles during the initial period of hypotension. In leg tumours, the predominant mechanism is attributable to reduced perfusion pressure induced by lowered MAP, which decreases flow to the tumour, probably because of relatively higher flow resistance. The vasoconstriction and vasomotion in tumour arterioles during DEA/NO-induced hypotension may reflect differences in regulatory metabolism of NO between neoplastic and normal arterioles. Thus, intravenous injection of a short-acting NO donor, DEA/NO, decreases MAP and heart rate, leading to subsequent decreases in tumour blood flow and oxygenation.     

Effects of a second heating on rat liver blood flow.

Effects of a second heating on blood flow in the liver and cardiac output were studied in Fischer rats. Heating was done by an experimental capacitive heating device using 8 MHz radiofrequency. Thermometry was performed at seven points around the liver with thermocouples. Blood flow and cardiac output were measured with the radioactive microsphere method. The liver was preheated for 30 min at 41 or 43 degrees C, and then reheated 1-7 days later at 41 degrees C for 15 min. Hepatic arterial blood flow, portal venous blood flow and the cardiac output were measured immediately before and at the end of the reheating. Heating the liver at 41 degrees C for 15 min without preheating slightly increased the hepatic arterial blood flow, and reheating 1-7 days after the first heating caused a greater increase in the hepatic arterial blood flow. Increase in hepatic arterial blood flow caused by reheatings pointed to the development of thermotolerance or thermal adaptation in the hepatic artery. When the liver was heated at 41 degrees C for 15 min without preheating, the portal venous blood flow remained almost unchanged 1-7 days after the heating. On the other hand, a reheating at 41 degrees C for 15 min applied 1-7 days after the preheating reduced the portal venous blood flow. Reduction in portal venous blood flow was approximately parallel to reduction in cardiac output by reheating, pointing to the existence of a causal relationship. Reduction in portal venous blood flow by reheating may also be, in part, due to the decrease in the splanchnic blood flow resulting from a systemic adaptation to the heat stress.     

Effects of a second heating on rat liver blood flow

Effects of a second heating on blood flow in the liver and cardiac output were studied in Fischer rats. Heating was done by an experimental capacitive heating device using 8 MHz radiofrequency. Thermometry was performed at seven points around the liver with thermocouples. Blood flow and cardiac output were measured with the radioactive microsphere method. The liver was preheated for 30 min at 41 or 43°C, and then reheated 1–7 days later at 41 °C for 15 min. Hepatic arterial blood flow, portal venous blood flow and the cardiac output were measured immediately before and at the end of the reheating. Heating the liver at 41°C for 15 min without preheating slightly increased the hepatic arterial blood flow, and reheating 1–7 days after the first heating caused a greater increase in the hepatic arterial blood flow. Increase in hepatic arterial blood flow caused by reheatings pointed to the development of thermotolerance or thermal adaptation in the hepatic artery. When the liver was heated at 41°C for 15 min without preheating, the portal venous blood flow remained almost unchanged 1–7 days after the heating. On the other hand, a reheating at 41°C for 15 min applied 1–7 days after the preheating reduced the portal venous blood flow. Reduction in portal venous blood flow was approximately parallel to reduction in cardiac output by reheating, pointing to the existence of a casual relationship. Reduction in portal venous blood flow by reheating may also be, in part, due to the decrease in the splanchnic blood flow resulting from a systemic adaptation to the heat stress.     

Significance of duplex/colour Doppler sonography in hepatic arterial chemotherapy for patients with liver metastases from colorectal carcinoma.

AIMS: The aim of the study was to evaluate the importance of duplex/colour Doppler ultrasound in a protocol of hepatic regional chemotherapy, by measuring the blood flow in the hepatic artery, portal vein, hepatic veins, and inferior caval vein of patients with unresectable liver metastases from colorectal carcinoma. METHODS: Thirty-nine consecutive subjects were selected for this study, including 21 patients who had unresectable histologically confirmed liver metastases from colorectal carcinoma (Group A), and 18 asymptomatic volunteers as normal controls (Group B). All subjects of Groups A and B were examined using duplex/colour Doppler sonography. After the ultrasound study, all patients of Group A were submitted to the administration of high dose mitomycin C into the hepatic artery, with concomitant detoxication of post-hepatic venous blood. RESULTS: The mean value of the hepatic artery blood flow was significantly higher (P=0.0009) in liver metastases patients (361 ml/min, SEM=24 ml/min) than in normal controls (245 ml/min, SEM=20 ml/min). Also, the mean Doppler perfusion index was higher in liver metastases patients than in normal controls. For each patient of Group A, the total dose of mitomycin C to be infused was calculated based on the blood flow in the hepatic artery. In this way the concentration of mitomycin C in the hepatic artery was always greater than 3 microg/ml. The duration of detoxication was calculated based on the blood flow in the inferior caval vein. For two patients only, the blood flow was lower than 1000 ml/min, with the necessity to protract the duration of detoxication over 2 hours. CONCLUSIONS: The measurement of the blood flow in hepatic vessels of patients with liver metastases seems to be very important in establishing the total dose of drug which has to be infused in hepatic arterial chemotherapy, and to determine the duration of concomitant detoxication of post-hepatic venous blood.     

Regulation of B16F1 melanoma cell metastasis by inducible functions of the hepatic microvasculature

We have previously shown that circulating intravascular cells generally arrest by mechanical restriction in the hepatic sinusoids, causing rapid release of nitric oxide (NO) which is cytotoxic to these cells and inhibits their growth into metastatic tumours. Here, we present evidence that these NO-dependent cytotoxic mechanisms are susceptible to upregulation by lipopolysaccharide (LPS). Five x 10(5) fluorescently labelled melanoma cells were injected into the mesenteric vein of C57BL/6 mice to effect their localisation in the hepatic microvasculature. Test mice were then given 1 mg/kg LPS intraperitoneally (i.p.) to activate the microvascular cells. By electron paramagnetic resonance (EPR) spectroscopy, the expression of NO in the liver was significantly increased by 8 h in the LPS-treated mice. The non-selective NO synthase inhibitor L-NAME inhibited the induction of NO by LPS, while its inactive enantiomer D-NAME had no significant effect. Using immunohistochemistry (IHC), iNOS-positive microvascular cells were detected in the terminal portal venule (TPV) region of the liver 8 h after LPS stimulation. LPS treatment also increased the retention of melanoma cells in the liver between 8 and 24 h, especially in the TPV region. Eight hours after cell injection, local expression of VCAM-1 and ICAM-1 was detected by double-label immunohistochemistry at the sites of tumour cell arrest. Expression of these adhesion molecules was enhanced in mice treated with LPS. Using flow cytometry, 98% of the B16F1 melanoma cells expressed VLA-4, the counter receptor of VCAM-1, and approximately 1.5% expressed LFA-1, the counter receptor of ICAM-1. LPS did not significantly alter the expression of either counter receptor on melanoma cells in vitro or in vivo. By DNA end-labelling, the rates of melanoma cell apoptosis were significantly increased from 8 to 24 h in the TPV region (but not in the sinusoids) of LPS-treated mice. Fourteen days after tumour cell injection, the LPS-treated mice had a significantly smaller hepatic metastatic tumour burden than the control mice. These data suggest that LPS can inhibit the metastasis of melanoma cells in the liver by inducing the expression of NO and adhesion molecules by the hepatic endothelium. The induction of iNOS and the inducible cytotoxic effect of LPS appear to be primarily located within the TPV region of the liver acinus.