粉防己碱、蝙蝠葛碱对高K~+引起突触体~(45)Ca内流的影响

<正> 钙离子在中枢神经系统的功能调控及许多病理过程中都有重要作用。而大多数经典钙拮抗剂对神经元Ca~(2+)通道不敏感。最近我们研究表明某些四氢异喹啉类化合物,如蝙蝠葛苏林碱对神经元Ca~(2+)通道有相对选择性拮抗作用。为了进一步确定四氢异喹啉类化合物对神经元Ca~(2+)通道的拮抗活性,我们观察粉防已碱、蝙蝠葛碱对突触体~(45)Ca内流的影响.实验方法Sprague-Dawley大鼠,体重200±23g,雌雄兼用。大鼠断头,迅速分离大脑皮层,制备突触体。用酚试剂法测定蛋白含量,突触体反应浓度为0.9g/L。按文献测定~(45)Ca内流。高K~+(65mmol/L)去极引起”快相”~(45)Ca内流反应时间为20s。净~(45)Ca内流量△(Ca~(2+))i=高K~+引起“快相”~(45)Ca内流—基础~(45)Ca内流。     

丹皮酚对体外培养乳鼠心肌细胞~(45)Ca摄取的影响

通过测定体外培养乳鼠心肌细胞~(45)Ca摄取及其搏动频率的变化,观察丹皮酚对心肌细胞Ca~(2+)内流的影响。结果50～400μg/ml的丹皮酚,能显著降低心肌细胞搏动频率,对心肌细胞快相(5min)和慢相(120min)~(45)Ca摄取均有显著抑制作用,且400μg/ml丹皮酚与10μmol/L的维拉帕米的作用相似。提示丹皮酚能抑制心肌细胞的Ca~(2+)内流,可能与阻滞慢钙通道有关。     

赛庚啶对离体犬心肌肌质网Ca~(2+),Mg~(2+)—ATP酶活性和~(45)Ca~(2+)摄取功能的影响

当赛庚啶浓度在8×10~(-6)mol/L～2×10~(-4)mol/L之间时,该药对正常犬心肌肌质网Ca~(2+),Mg~(2+)—ATP酶活性几乎没有影响,仅在10~(-3)mol/L时对该酶活性才有一定的抑制作用(抑制率为39.85%,P<0.01)。正常犬心肌肌质网的~(45)Ca~(2+)摄取过程有明显的时间依赖性,至第30 min,其~(45)Ca~(2+)摄取量可达312.79±22.25 nmol/mg protein.赛庚啶对心肌肌质网的~(45)Ca~(2+)摄取有一定的抑制作用,其IC_(50)为1.94×10~(-4)mol/L。     

八肽胆囊收缩素对抗吗啡抑制大鼠脑突触小体钙摄取的作用

用大鼠脑的膜制备观察吗啡和CCK-8对突触小体摄取~(45)Ca~(2+)的影响。吗啡(10 nmol/L～1μmo1/L)抑制突触小体对~(45)Ca的摄取,该作用能被1μmol/L纳洛酮完全阻断。CCK-8(10nmol/L～1μmol/L)本身能抑制突触小体~(45)Ca摄取,但它在10nmol/L和100 nmol/L时能对抗吗啡对~(45)Ca摄取的抑制作用,浓度提高到1μmol则不能对抗吗啡的这一作用。CCK-8抑制突触小体摄取~(45)Ca,以及对抗吗啡的~(45)Ca摄取抑制的作用,皆能被CCK受体拮抗剂丙谷酰胺(2μmol/L)所阻断.捉示CCK-8是通过激动CCK受体而拮抗吗啡抑制~(45)Ca摄取的,CCK-8的这一拮抗作用可能是其抗阿片作用的机理之一.     

Fura—2荧光测定眼镜蛇心脏毒引起细胞胞浆Ca~(2+)浓度的变化

用Fura—2荧光技术直接测定眼镜蛇心脏毒(CTX)对大鼠泪腺细胞胞浆Ca~(2+)浓度的影响。在无Ca~(2+)的介液下,CTX可使胞浆Ca~(2+)浓度升高;随之加入1mmol/L CaCl_2可使胞浆Ca~(2+)浓度进一步升高。表明CTX能引起胞内Ca~(2+)释放和胞外Ca~(2+)内流。8mmol/L CaCl_2能阻断CTX升高胞浆Ca~(2+)浓度的作用。     

三七皂甙对血管平滑肌α受体引起~(45)Ca外溢与内流的影响

在血管平滑肌,三七总皂甙明显减少苯肾上腺素引起的~(45)Ca内流量,不影响高钾引起的~(45)Ca内流;而硝苯吡啶几乎完全阻断后一种的~(45)Ca内流。三七总皂甙不抑制~(45)Ca外溢。结果表明,三七总皂甙能特异阻断血管平滑肌α受体操纵的Ca~(2+)通道而不影响胞内Ca~(2+)释放过程。     

三七皂甙对血管平滑肌上受体操纵Ca~(2 )通道的特异性作用(英文)

三七皂甙能明显抑制狗肠系膜动脉及大隐静脉α肾上腺素能受体触发的收缩反应及~(45)Ca内流(从0.36±0.03降至0.14±0.05μmol·g~(-1)组织湿重),但对高K~ 引起的Ca~(2 )内流无影响。三七皂甙不影响Ca~(2 )释放及受体的亲和力。提示三七皂甙具有特异性阻断受体操纵Ca~(2 )通道的特性,对电位依赖性Ca~(2 )通道无作用。     

尼莫地平对离体豚鼠左心房的抑制作用及其机理探讨

尼莫地平(50μmol/L)明显减低豚鼠左心室收缩幅度,其强度与戊脉安(25μmol/L)相当;明显抑制正阶梯现象,但不象戊脉安那样使其翻转成负阶梯现象;明显抑制静息后增强效应;逆转或预防哇巴因诱发的心律失常。以上结果提示尼莫地平既能减少胞外Ca~(2+)通过Ca~(2+)通道内流,又能减少胞内贮Ca~(2+)释放。     

蛇床子素对豚鼠离体回肠和结肠带的作用

以豚鼠离体回肠和结肠带为标本,观察蛇床子素(Ost)的作用与Ca~(2+)的关系。结果表明:Ost和钙拮抗剂Ver产生剂量依赖性抑制乙酰胆碱(ACh)、组胺及KCl所致回肠条或结肠带的收缩;非竞争性拮抗CaCl_2累积量—效曲线,pD_2分别为4.41±0.15,7.0±0.2。Ost 100μmol/L和Ver 1μmol/L均能对抗小剂量Ca~(2+)所致结肠带收缩,但被加入较大量Ca~(2+)所取消。Ost和Ver均能抑制ACh诱导的依内钙性收缩,不影响依外钙性收缩。结果提示Ost具有钙拮抗作用,其作用方式与Ver类似。     

心肌细胞钙通道的特性与调节

<正> 可兴奋细胞的跨膜Ca~(2+) 内流对维持其细胞功能具有极其重要的意义,它参与许多重要生理过程,诸如:肌肉收缩、递质释放、激素分泌、酶活性调节和膜离子通透性等。有关Ca~(2+)在心肌兴奋—收缩耦联过程中的作用正在深入而广泛地进行研究。 心肌细胞在静息状态时,细胞内游离的Ca~(2+)浓度约在10~(-7)mol/L,兴奋时则增高到10~(-6)～10~(-5)mol/L范围,此改变一方面是因胞外Ca~(2+)(10~(-3)mol/L)进入     

地奥心血康对大鼠主动脉~（45）Ca内流的影响

用~（４５）Ｃａ跨膜流动测定方法研究地奥心血康及维拉帕米对大鼠主动脉Ｃａ~（２＋）跨膜内流的影响。结果：地奥心血康５－５００μｇ／ｍＬ和维拉帕米０．０１１－１．１μｍｏｌ／Ｌ，不影响静息~（４５）Ｃａ的内流，但均能浓度依赖性抑制去甲肾上腺素１．２ｍｏｌ／Ｌ和ＫＣｌ１００ｍｍｏｌ／Ｌ引起的~（４５）Ｃａ内流。说明地奥心血康能阻滞细胞外Ｃａ~（２＋）通过受体操纵与电压依赖钙离子通道的内流。     

汉防己甲素对气管平滑肌45Ca内流的影响

本文应用国产⁴⁵CaCl₂研究汉防已甲素(以下简称为汉甲)对气管平滑肌钙内流的影响。汉甲对犬与豚鼠气管平滑肌基础的⁴⁵Ca内流量无明显的影响;60μg/ml汉甲对犬气管平滑肌组胺兴奋与高钾打开电位操纵通道(POC)的5 min⁴⁵Ca内流量的抑制率,分别为11.1%与38.3%;60μg/ml汉甲对豚鼠气管平滑肌组胺与高钾兴奋的5min⁴⁵Ca内流量的抑制率分别为48.7%与33.3%,10μg/ml或20μg/ml汉甲虽对犬或豚鼠气管平滑肌组胺兴奋的、高钾兴奋和/或打开POC的⁴⁵Ca内流量具有一定的抑制作用,但无统计学意义。说明汉甲对气管平滑肌POC与受体操纵通道(ROC)均有阻断作用,由于对高钾兴奋和/或打开POC的⁴⁵Ca内流阻断是完全的,而对组胺兴奋和打开RCC的⁴⁵Ca内流阻断是部分的,提示汉甲优先阻断气管平滑肌的POC,60μg/ml汉甲对气管平滑肌POC的阻断强度与50μg/ml异搏定相当。汉甲的钙通道阻断作用可能与其拮抗过敏介质收缩气管的作用有关。     

山莨菪碱对A_(23187)诱导的血小板内游离钙升高的影响

应用Quin-2测得含有1mmol/L CaCl_2和2mmol/L EGTA的介质中血小板内静息游离钙浓度为52.1±5.2nmol/L和28.4±5.1nmol/L。A_(23187)诱导的血小板在有钙或无钙时胞浆游离钙增加的峰值分别为145.8±30.8nmol/L和34.4±2.4nmol/L,山莨菪碱对静息游离钙和无外源钙时A_(23187)刺激的游离钙无影响,山莨菪碱(100μmol/L,25μmol/L)、维拉帕米(10μmol/L)分别降低有外源钙时A_(23187)诱导的游离钙峰值38%、34%、25%。山莨菪碱具有钙拮抗作用。     

The erythrocyte-perfused “working heart” model: Hemodynamic and metabolic performance in comparison to crystalloid perfused hearts

A brief period of ischemia was used to evaluate an erythrocyte-enriched Krebs-Henseleit (KH) buffer (n=8) compared to KH only (n=8) in an isolated working rabbit heart. Experimental protocol was as follows: preischemic baseline, 5 min of global ischemia followed by 45 min of reperfusion. Preischemic heart rate was identical, coronary flow was significantly lower (2.7 versus 5.6 mL/min/g wet wt, p<0.01), the other hemodynamic and biochemical values were significantly higher in erythrocyte-perfused hearts: aortic flow 23.5 versus 12.0, p<0.01; cardiac output 26.2 versus 17.6, p<0.01; all in mL/min/g wet wt; dp/dt max 1286 versus 997 mmHg/s, p<0.01; myocardial oxygen consumption 3.5 versus 2.3 μmol/min/g wet wt, p<0.05. During early reperfusion, in the erythrocyte-perfused hearts, coronary flow further increased (p<0.003), the other hemodynamic parameters returned to baseline values in both groups. High-energy phosphates showed significantly higher values (ATP 2.0±0.1 versus 1.3±0.1, p<0.05; CrP 2.0±0.2 versus 1.6±0.1, p<0.05 all in μmol/g wct wt), water content was significantly lower (81% versus 74%, p<0.05) in erythrocyte-perfused hearts. It can be concluded that the erythrocyte-perfused working heart model provides excellent oxygenation, leading to superior hemodynamic and metabolic performance. Additionally, in the erythrocyte-perfused hearts preservation of coronary flow reserve underlines the physiological competency of this prepar-ation.     

普罗帕酮对豚鼠心肌力学的影响

目的研究普罗帕酮心肌变力性作用并从组织水平探讨其作用机制。方法采用离体乳头肌灌流的方法观察普罗帕酮对豚鼠乳头肌主动张力(DT)、主动张力上升最大速度(+dT/dtmax)、主动张力下降最大速度(-dT/dtmax)的影响。经钙通道阻滞剂尼卡地平及Na+/Ca2+交换体阻滞剂KBR7943预处理后,分别观察普罗帕酮的上述作用。结果①在场刺激引起收缩的乳头肌,0.1、1、10、30μmol·L-1普罗帕酮分别使DT由对照(0.18±0.05)g降至(0.14±0.03)、(0.12±0.03)、(0.08±0.02)、(0.05±0.02)g(P<0.01),IC50为10μmol·L-1;+dT/dtmax由对照(1.79±0.45)mg·s-1降至(1.58±0.37)、(1.46±0.29)、(1.26±0.19)、(0.97±0.15)mg·s-1(P<0.01);-dT/dtmax由对照(1.61±0.29)mg·s-1降至(1.45±0.28)、(1.26±0.19)、(0.92±0.26)、(0.78±0.22)mg·s-1。②尼卡地平(2.0μmol·L-1)阻断L型钙通道后,普罗帕酮(10μmol·L-1)使DT、+dT/dtmax、-dT/dtmax由(0.10±0.02)g、(1.32±0.24)mg·s-1、(1.24±0.17)mg·s-1分别降低至(0.06±0.01)g、(1.11±0.23)mg·s-1、(0.89±0.23)mg·s-1(P<0.01)。③KBR7943(1.0μmol·L-1)阻断Na+/Ca2+交换体后,普罗帕酮(10μmol·L-1)使DT、+dT/dtmax、-dT/dtmax由(0.18±0.02)g、(1.48±0.28)mg·s-1、(1.63±0.23)mg·s-1分别降低至(0.09±0.01)g、(1.16±0.01)mg·s-1、(1.05±0.23)mg·s-1(P<0.01)。结论①普罗帕酮剂量依赖性抑制豚鼠乳头肌力学各项指标,显示有负性肌力作用。②普罗帕酮对L型钙通道及反向Na+/Ca2+交换的抑制作用参与其负性肌力的作用,且前者作用较大。     

赛庚啶对豚鼠乳头状肌的收缩性与动作电位的影响

Cyp对豚鼠孔头状肌有浓度依赖性负性肌力作用,提高浴液钙浓度此作用减弱,对高K~+除极后ISO恢复的收缩抑制作用更强。较高浓度的Cyp使频率依赖性正阶梯现象取消和翻转。对乳头状肌AP,Cyp浓度依赖性地使APD_(20),APD_(50),APD_(90)和ERP缩短。灌流液中Ca~(2+)降低或升高分别使该作用增强或减弱,K~+的改变对其作用影响较小。提示Cyp对豚鼠乳头状肌收缩性和AP的作用可能主要是抑制心肌跨膜Ca~(2+)内流所致。     

小檗碱对大鼠再灌心律失常及钙调节的作用

小檗碱（Ｂｅｒ，１０ｍｇ·ｋｇ－１）使缺血／再灌后ＶＴ发生率明显降低，持续时间明显缩短，无１例发生ＶＦ及死亡，与对照组比较差异有显著性。离体实验表明：小檗碱（３０μｍｏｌ·Ｌ－１），能抑制高钙条件下Ｃａ２＋内流，而增加低钙条件下的Ｃａ２＋内流。结果表明：小檗碱具有预防再灌心律失常作用；不同Ｃａ２＋浓度能够影响心肌４５Ｃａ内流；小檗碱对心肌Ｃａ２＋内流有双向调节作用，尤其在高Ｃａ２＋条件下，降低４５Ｃａ内流可能是其抗心律失常作用机制之一。     

EFFECT OF CROSS-FOSTERING ON NEONATAL SODIUM BALANCE AND ADULT BLOOD PRESSURE IN THE SPONTANEOUSLY HYPERTENSIVE RAT

1. The aim of the present study was to compare electrolyte handling in naturally reared neonatal spontaneously hypertensive rats (SHR) with those reared by a Wistar-Kyoto (WKY) rat foster mother (denoted SHRX), as cross-fostering SHR pups to a WKY rat dam lowers adult blood pressure in the SHR. 2. The electrolyte content of WKY rat and SHR dams’ milk was determined and electrolyte intake and urinary excretion rates were calculated in both naturally reared and cross-fostered WKY rat and SHR pups. 3. The milk sodium concentration fell in both strains (WKY rat: 31.8 ± 2.0 to 15.2 ± 1.2 mmol/L; SHR 31.9 ± 2.5 to 18.2 ± 1.6 mmol/L; P < 0.001), as did potassium (P < 0.001), over lactation, but there were no differences between strains. Calcium and magnesium concentrations increased (P< 0.001), although SHR dam's milk contained less calcium (P < 0.001) than that of WKY rat dams during the third week of lactation. 4. Spontaneously hypertensive rat pups ingested less milk (P<0.05) than WKY rat pups; therefore, their cumulative sodium intake over postnatal days 4–15 was significantly lower than that of WKY rat pups (WKY rat vs SHR: 84.4 ± 3.6 vs 59.7 ± 2.6 μmol/g bodyweight, respectively; P < 0.05) and fostered SHRX pups (77.7 ± 7.0 μmol/g bodyweight; P < 0.05). Potassium and magnesium intakes were comparable between SHR, WKY rat and SHRX pups, but SHR pups ingested significantly less calcium than either WKY rat pups (136.1 ± 6.4 vs 200.1 ± 9.5p, mol/g bodyweight, respectively; P<0.05) or SHRX pups (200.0 ± 18.0 μmol/g bodyweight; P<0.05). 5. These data show that the neonatal SHR experiences a period of sodium deficiency during the developmental stage when cross-fostering is effective in lowering blood pressure. This is consistent with the reported up-regulation of the renin-angiotensin system observed in SHR at this time and may have a long-term influence on blood pressure.