右美托咪定经鼻给药在胸腔镜肺叶切除术中的疗效观察

目的 探讨不同剂量右美托咪定术前经鼻喷雾给药在胸腔镜下肺叶切除术患者中应用的安全性及有效性。方法 本研究为前瞻性随机双盲安慰剂对照临床研究,选择2017年6月~12月本院收治的90例ASAⅠ~Ⅱ级择期全麻下行胸腔镜下肺叶切除术患者,随机分为三组:麻醉诱导前45 min分别经鼻喷雾使用右美托咪定1 μg/kg（D1组）、1.5 μg/kg（D2组）和生理盐水0.01 ml/kg（C组）。观察患者用药后15 min、30 min及45 min的改良警觉镇静评分（MOAA/S）,记录麻醉诱导和气管插管前后血流动力学变化,同时记录术后PACU停留时间以及躁动、恶心呕吐的发生情况。结果 D1、D2组右美托咪定经鼻喷雾给药后30 min和45 min的MOAA/S评分及用药后45 min的BIS值显著低于C组,差异有统计学意义（P＜0.05）;D1与D2组间比较,D2组给药后30 min的MOAA/S评分显著低于D1组,差异有统计学意义（P＜0.05）,给药后45 min D2组的BIS值显著低于D1组,但是两组MOAA/S评分差异无统计学意义（P＞0.05）。D1、D2组患者诱导及气管插管前后心率、血压波动显著低于C组,差异有统计学意义（P＜0.05）;术后躁动和恶心呕吐的发生率均低于C组,差异有统计学意义（P＜0.05）。术后PACU停留时间比较三组差异无统计学意义（P＞0.05）。结论 右美托咪定经鼻喷雾术前给药可以安全有效地用于胸腔镜下肺叶切除术患者,提供良好的术前镇静,稳定围术期血流动力学,降低术后躁动和恶心呕吐的发生率。与1.0 μg/kg组比较,1.5 μg/kg右美托咪定经鼻给药可以显著缩短镇静起效时间。     

复方利多卡因乳膏在气管插管全麻中的应用

目的观察复方利多卡因乳膏应用于气管插管全麻,对抑制插管应激反应和术后咽喉痛的效果。方法60例ASA1-Ⅱ级拟施气管插管全麻择期手术患者随机均分为两组。对照组（Ⅰ组）和实验组（Ⅱ组）分别将石蜡油和复方利多卡因乳膏均匀涂于气管插管的套囊及前端,麻醉诱导后行气管内插管。分别记录诱导前、插管前、插管即刻及插管后3min时患者的收缩压（SBP）、舒张压（DBP）、心率（HR）。并记录是否有术后咽喉痛及性质。结果Ⅰ组在插管即刻和插管后3min较插管前SBP、DBP、HR明显增加,差异有统计学意义（P〈0.05）;而Ⅱ组病人插管即刻和插管后3min上述指标较插管前无显著差异（P〉0.05）。组间比较,Ⅰ组插管后SBP、DBP、HR均较Ⅱ组明显增加,差异有统计学意义（P〈0.05）。Ⅰ组患者术后咽喉痛、喉部异物感的发生率显著高于Ⅱ组（P〈0.01）。结论复方利多卡因乳膏可以有效抑制气管插管全麻所引起的插管应激反应和术后咽喉痛。     

右旋美托咪啶镇静治疗对严重创伤后炎症因子的影响

 目的：探讨右旋美托咪啶（DEX）在严重创伤患者短期镇静治疗中对严重创伤后炎症因子的影响。方法：随机将60例入住重症监护病房（ICU）的严重创伤患者分为3组：DEX镇静组（DEX组,n=20）、咪达唑仑（MDZ）镇静组（MDZ组,n=20）和不用镇静剂的对照组（n=20）。DEX组：先静脉注射DEX负荷量1~2 μg/kg（>10 min）,继以微量注射泵持续静脉泵注维持量0.2~0.7 μg·kg^-1·h^-1。MDZ组：先静脉注射MDZ负荷量0.03~0.3 mg/kg,继以微量注射泵持续静脉泵注维持量0.03~0.2 mg·kg^-1·h^-1。镇静2组均以Ramsay氏镇静评分分级Ⅱ~Ⅳ级为镇静目标,根据Ramsay评分调整用量,实施2 d的短程镇静治疗。分别检测患者在入院时、24 h和48 h血清中白细胞介素1（IL-1)、IL-6、肿瘤坏死因子α（TNF-α）和C反应蛋白（CRP）水平。结果：3组患者TNF-α、IL-1、IL-6和CRP水平在入住ICU时均明显高于正常值,3组差异无统计学意义（P>0.05）;对照组TNF-α、IL-1、IL-6和CRP在24 h和48 h逐步升高,而DEX组和MDZ组的上述指标有所下降,分别与对照组比较差异有统计学意义（P<0.05）;DEX组和MDZ组TNF-α、IL-1、IL-6和CRP水平在24 h无显著差异（P>0.05）,但在48 h差异显著（P<0.05）。结论：右旋美托咪啶可在一定程度上降低创伤后过度应激反应,阻止炎症介质的进一步产生和释放,有助于严重创伤患者的稳定和恢复。     

黄芪甲苷拮抗马兜铃酸Ⅰ所致的急性肾小管损伤

 目的：观察黄芪甲苷对马兜铃酸Ⅰ所致的急性肾小管损伤的影响。方法：（1）体外实验：四甲基偶氮唑盐（MTT）法观察黄芪甲苷对马兜铃酸Ⅰ所致人近曲小管上皮细胞（HK-2）存活率降低的拮抗作用;（2）动物体内实验：马兜铃酸Ⅰ腹腔注射6 d建立昆明小鼠急性肾损伤模型,同时用50 mg·kg^-1·d^-1黄芪甲苷灌胃进行干预治疗。7 d后检测尿蛋白、尿γ-谷氨酰转移酶（γ-GT）、血清肌酐（SCr）、血尿素氮（BUN）水平的变化和肾脏组织形态学变化。结果：（1）黄芪甲苷能增加马兜铃酸Ⅰ处理的HK-2细胞存活率,并呈剂量依赖趋势;（2）黄芪甲苷干预组小鼠尿蛋白、尿γ-GT、SCr、和BUN的水平均低于马兜铃酸肾损伤组;近曲小管坏死和裸基底膜面积也较马兜铃酸肾损伤组明显改善。结论：黄芪甲苷可以拮抗马兜铃酸Ⅰ诱导的急性肾小管损伤。     

ProSeal喉罩通气全麻在高血压患者腹腔镜胆囊切除术中的临床应用

目的观察高血压病人腹腔镜胆囊切除术中应用ProSeal喉罩通气全麻对患者血压和心率的影响。方法高血压腹腔镜胆囊切除术患者120例,ASAⅠ～Ⅱ级,随机分为喉罩组和气管插管组,每组60例。记录诱导前（T0）、置入喉罩/插管前即刻（T1）、置入喉罩/插管后1min（T2）、3min（T3）、胆囊切除时（T4）、拔喉罩或拔管时（T5）6个时间点的HR、MAP、BIS,并进行组间比较。结果气管插管组于插管后1min、3min、拔管时均较麻醉前、插管前即刻及喉罩组HR明显增快、MAP明显升高;瑞芬太尼、顺势阿曲库铵消耗总量、术毕24h内咽喉疼痛例数气管插管组要明显高于喉罩组,胃管置入比例两组则无明显差异。结论喉罩通气全麻在高血压病人腹腔镜胆囊切除术中可有效预防心血管应激反应,避免血压和心率的剧烈波动。     

瑞舒伐他汀联合厄贝沙坦对大鼠心肌肥厚性重构的影响

 目的: 探讨瑞舒伐他汀联合厄贝沙坦对心肌肥厚大鼠心室重构的影响。方法: SPF级体重240~300 g雄性SD大鼠50只随机分为对照组、模型组、瑞舒伐他汀组、厄贝沙坦组和联合组。除对照组外,其余4组大鼠连续14 d给予皮下注射异丙肾上腺素(2.5 mg/kg)。自造模当天开始,对照组和模型组给予生理盐水灌胃,瑞舒伐他汀组、厄贝沙坦组和联合组分别给予瑞舒伐他汀(4 mg·kg^-1·d^-1)、厄贝沙坦(15 mg·kg^-1·d^-1)和瑞舒伐他汀(4 mg·kg^-1·d^-1)+厄贝沙坦(15 mg·kg^-1·d^-1)灌胃处理,连续干预4周。干预结束后,分别测定各组大鼠心脏质量指数、左室质量指数,HE染色观察心肌细胞肥大程度,RT-PCR测定肥大相关因子ANF、β-MHC和AT1受体(AT1R)的mRNA表达,Western blot法测定AT1R的蛋白表达。结果: 与对照组相比,模型组的心脏质量指数、左室质量指数、ANF和β-MHC的mRNA表达均增加(P<0.05);与模型组相比,瑞舒伐他汀组和厄贝沙坦组的心脏质量指数、左室质量指数、ANF和β-MHC的mRNA表达均降低(P<0.05),联合组效果优于单药组(P<0.05)。瑞舒伐他汀组及厄贝沙坦组AT1R的mRNA及蛋白表达均低于模型组(P<0.05),而联合组AT1R的mRNA及蛋白表达水平低于各单独用药组(P<0.05)。结论: 瑞舒伐他汀及厄贝沙坦均能不同程度地改善心肌肥厚。它们的抗心肌肥厚作用可通过下调AT1R的mRNA和蛋白表达实现。联合用药的效果优于单一药物。     

叶酸对去卵巢大鼠抗氧化酶、一氧化氮合酶和一氧化氮的影响

 目的: 观察叶酸对去卵巢大鼠抗氧化酶、一氧化氮合酶和一氧化氮的影响。方法: 40只3月龄健康雌性SD大鼠,随机分成5组:假手术组、去卵巢组、二乙基己烯雌酚(0.03 mg·kg^-1·d^-1)组、低剂量(5 mg·kg^-1·d^-1)叶酸组和高剂量(20 mg·kg^-1·d^-1)叶酸组。各组大鼠于术后1周开始灌胃给药,假手术组和去卵巢组给予蒸馏水,10周后,取L₅椎体和右股骨行骨密度(BMD)检测;测定血浆和骨匀浆总抗氧化能力(TAC)、谷胱甘肽过氧化物酶(GSH-Px)、丙二醛(MDA)、一氧化氮合酶(NOS)和一氧化氮(NO)水平。结果: 与假手术组比较,去卵巢组大鼠L₅椎体和股骨BMD显著降低(P < 0.01),血浆GSH-Px、NO和骨匀浆TAC、GSH-Px、NOS及NO水平明显降低(P < 0.01),MDA浓度升高显著(P < 0.01);与去卵巢组大鼠比较,高剂量叶酸组大鼠L₅椎体和股骨BMD增加(P < 0.01),骨匀浆TAC、GSH-Px、NOS和NO水平升高(P < 0.01),MDA浓度降低(P < 0.01),血浆GSH-Px和NO水平升高。结论: 去卵巢大鼠体内抗氧化酶、NOS和NO水平降低,氧化应激参与了去卵巢大鼠骨质疏松的发生;高剂量叶酸能提升去卵巢大鼠腰椎和股骨BMD,提高其体内抗氧化酶、NOS和NO水平,改善氧化应激,这可能是高剂量叶酸防治去卵巢大鼠骨质疏松的机制之一。     

长托宁用于喉罩全麻术前用药的临床观察

目的研究选择性M受体拮抗剂长托宁用于喉罩全麻术前用药的临床效果。方法选取ASAⅠ～Ⅱ级行择期腹腔镜下胆囊切除术患者90例，随机分为3组（每组30例）：对照组（A组），术前不应用任何抗胆能药；阿托品组（B组）和长托宁组（C组），麻醉诱导前30min肌肉注射阿托品或长托宁0．01mg／kg，麻醉诱导后置入标准型喉罩后接麻醉机行机械通气；分别记录气管插管后5min（T1）、气管插管后30min（T2）、气管拨管前（T3）气道内分泌物量以及心率变化。结果在T1、T2、T3三个时点，B组和C组患者的气道分泌物明显少于A组（P〈0．05）；B组在T1时间点的心率明显高于A组与C组（P〈0．05）。结论长托宁用于喉罩全麻术前用药临床效果较好。     

无痛肠镜麻醉中不同给药方法对呼吸和循环的影响

 目的：比较丙泊酚滴定麻醉和传统麻醉方法用于无痛肠镜时呼吸和循环的变化,寻找对呼吸循环影响小的给药方法;评估不同滴定诱导终点在无痛肠镜麻醉中的差别。方法：拟行无痛肠镜检查患者90例,随机分为3组,MOAA/S评分达1分为诱导终点组（M组）、睫毛反射消失为诱导终点组（E组）及对照组（C组）,每组30例。记录各组呼吸抑制、低血压的发生例数和苏醒时间。记录不同时点的平均血压、心率和脉搏氧饱和度。结果：和C组相比,M组和E组呼吸抑制和低血压的发生例数少（P<0.05）,苏醒时间短(P<0.05)。M组和E组并发症发生率及血流动力学改变无显著差异（P>0.05）。结论：相比传统用药方法,丙泊酚滴定麻醉用于肠镜检查可减少对呼吸和循环的影响,苏醒迅速。以MOAA/S达到1分或睫毛反射消失为诱导终点对呼吸和循环的影响无显著差别。     

视可尼喉镜与普通直接喉镜在小儿全身麻醉气管插管中的对比研究

目的比较视可尼喉镜与普通直接喉镜在小儿全身麻醉气管插管中的应用价值、安全性和对应激反应的影响。方法选取需全身麻醉婴幼儿60例（其中新生儿16例）,其中男性36例,女性24例;年龄10天~3岁,平均年龄1.1岁。随机分为2组,每组30例,其中新生儿8例,其余为1个月~3岁患儿。术前处理和麻醉诱导方法相同,Ⅰ组采用视可尼喉镜进行气管插管（经口、左侧磨牙入路）,Ⅱ组则采用普通直接喉镜进行气管插管,记录各组患儿插管时间,诱导前、插管前、插管后1、3、5、10min收缩压（SBP）、舒张压（DBP）、心率（HR）,计算HR与收缩压乘积（RPP）、全程监测脉搏血氧饱和度（SpO2）并于气管插管前和气管插管后5 min采动脉血检测血糖。结果Ⅰ组患儿用视可尼喉镜行气管插管时间虽略有缩短,但差异无统计学意义。血流动力学指标：组内各时点比较,两组患儿在诱导和插管时变化过程相似,诱导后至插管前HR、SBP、DBP及RPP比麻醉前明显降低（P〈0.01）;插管后1 min的比插管前的明显增高（P〈0.01）并且达到最高,以后逐渐降低;组间比较,两组患儿在麻醉前、诱导后及插管后3、5、10 min各指标差异无统计学意义,插管后1 minⅡ组患儿的HR、SBP、DBP及RPP比Ⅰ组的明显升高,差异有统计学意义（P〈0.05）。血糖：组内、组间,两组患儿插管过程中各时点之间均无明显变化（P〉0.05）。全部病例SpO2无变化。Ⅰ组内有10例困难气道患儿全部一次性插管过程顺利,Ⅱ组内有8例困难气道患儿,其中5例一次性插管过程成功。两组比较,差异有统计学意义（P〈0.05）。结论视可尼喉镜（儿童型）用于小儿气管插管简便易行,安全可靠,尤其对声门暴露不理想者更具优势;采用视可尼喉镜实施经口气管插管可引起与用直接喉镜气管插管相似的应激反应,但相比较轻。     

丙泊酚复合瑞芬太尼靶控输注对高血压患者脑电双频指数的影响

目的：研究丙泊酚复合瑞芬太尼靶控输注对高血压患者脑电双频指数的影响。方法：选择2015年1月至2016年3月在我院行丙泊酚复合瑞芬太尼靶控输注麻醉的高血压患者105例,根据使用瑞芬太尼靶控输注的浓度将患者分为3组,Ⅰ组浓度为2.0 ng/mL、Ⅱ组浓度为3.0 ng/mL、Ⅲ组浓度为4.0 ng/mL,其三组丙泊酚的靶浓度均为4μg/mL,每组各35例患者。观察比较三组患者在入室5 min(T0)、插管前(T1)、插管后1 min(T2)、插管后3 min(T3)以及插管后5 min(T4)各时间点的平均动脉压、心率以及脑电双频指数的变化,并比较其苏醒的时间。结果：Ⅰ组患者在T2、T3时间点的平均动脉压与心率均明显的高于T1时间点,Ⅱ组患者在T2时间点的平均动脉压与心率均明显的高于T1时间点,比较差异具体统计学意义(P<0.05);在T2、T3与T4时间点上,Ⅲ组患者的脑电双频指数明显的低于Ⅱ组患者与Ⅰ组患者,比较差异具有统计学意义(P<0.05);Ⅲ组患者的苏醒时间明显的长于Ⅰ组、Ⅱ组患者,比较差异显著(P<0.05)。结论：使用丙泊酚复合瑞芬太尼靶控输注麻醉高血压患者,其脑电双频指数会随着瑞芬太尼的浓度而降低,减低插管应激反应,并能够维持血流动力学的平稳。     

小剂量艾司洛尔对丙泊酚麻醉诱导静脉注射疼痛的影响

目的 研究小剂量艾司洛尔对丙泊酚麻醉诱导静脉注射疼痛的影响.方法 选择2007年6月至2008年3月全身麻醉下行择期手术的患者80例,随机分为对照组(A组)和艾司洛尔组(B组),每组40例.A组进行常规麻醉诱导,B组先静脉注射艾司洛尔0.5 mg/kg,30 s后再进行常规麻醉诱导.采用4分制对两组的丙泊酚注射痛进行评分,比较麻醉前、诱导完毕、气管插管完成即刻、气管捅管后2、4、6、8与10 min的血压和心率变化及诱导期间注射痛的发生率.结果 两组麻醉前和诱导期间各时点血压和心率的变化差异无统计学意义(均P>0.05).诱导期间丙泊酚总的注射疼痛发生率A组为65%(26/40),B组为23%(9140)(P<0.01).其中重度疼痛发生率A组为20%(8/40),B组为3%(1/40)(P<0.05);而轻度和中度疼痛发生率两组间差异无统计学意义(P>0.05).结论 小剂量艾司洛尔可减轻丙泊酚麻醉诱导的静脉注射疼痛.     

Prevention of etomidate-induced myoclonus during anesthetic induction by pretreatment with dexmedetomidine

Myoclonus induced by etomidate during induction of general anesthesia is undesirable. This study evaluated the effect of dexmedetomidine (DEX) pretreatment on the incidence and severity of etomidate-induced myoclonus. Ninety patients undergoing elective surgical procedures were randomly allocated to three groups (n=30 each) for intravenous administration of 10 mL isotonic saline (group I), 0.5 µg/kg DEX in 10 mL isotonic saline (group II), or 1.0 µg/kg DEX in 10 mL isotonic saline (group III) over 10 min. All groups subsequently received 0.3 mg/kg etomidate by intravenous push injection. The incidence and severity of myoclonus were recorded for 1 min after etomidate administration and the incidence of cardiovascular adverse events that occurred between the administration of the DEX infusion and 1 min after tracheal intubation was recorded. The incidence of myoclonus was significantly reduced in groups II and III (30.0 and 36.7%), compared with group I (63.3%). The incidence of severe sinus bradycardia was significantly increased in group III compared with group I (P<0.05), but there was no significant difference in heart rate in groups I and II. There were no significant differences in the incidence of low blood pressure among the 3 groups. Pretreatment with 0.5 and 1.0 µg/kg DEX significantly reduced the incidence of etomidate-induced myoclonus during anesthetic induction; however, 0.5 µg/kg DEX is recommended because it had fewer side effects.     

Induction of anesthesia in coronary artery bypass graft surgery: the hemodynamic and analgesic effects of ketamine

OBJECTIVE

The aim of this prospective, randomized study was to evaluate the hemodynamic and analgesic effects of ketamine by comparing it with propofol starting at the induction of anesthesia until the end of sternotomy in patients undergoing coronary artery bypass grafting surgery.

INTRODUCTION

Anesthetic induction and maintenance may induce myocardial ischemia in patients with coronary artery disease. A primary goal in the anesthesia of patients undergoing coronary artery bypass grafting surgery is both the attenuation of sympathetic responses to noxious stimuli and the prevention of hypotension.

METHODS

Thirty patients undergoing coronary artery bypass grafting surgery were randomized to receive either ketamine 2 mg.kg⁻¹ (Group K) or propofol 0.5 mg.kg⁻¹ (Group P) during induction of anesthesia. Patients also received standardized doses of midazolam, fentanyl, and rocuronium in the induction sequence. The duration of anesthesia from induction to skin incision and sternotomy, as well as the supplemental doses of fentanyl and sevoflurane, were recorded. Heart rate, mean arterial pressure, central venous pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, cardiac index, systemic and pulmonary vascular resistance indices, stroke work index, and left and right ventricular stroke work indices were obtained before induction of anesthesia; one minute after induction; one, three, five, and ten minutes after intubation; one minute after skin incision; and at one minute after sternotomy.

RESULTS

There were significant changes in the measured and calculated hemodynamic variables when compared to their values before induction. One minute after induction, mean arterial pressure and the systemic vascular resistance index decreased significantly in group P (p<0.01).

CONCLUSION

There were no differences between groups in the consumption of sevoflurane or in the use of additional fentanyl. The combination of ketamine, midazolam, and fentanyl for the induction of anesthesia provided better hemodynamic stability during induction and until the end of sternotomy in patients undergoing coronary artery bypass grafting surgery.     

Histamine release during the induction of anesthesia with propofol in allergic patients: A comparison with the induction of anesthesia using midazolam-ketamine

OBJECTIVE: A prospective randomized controlled study was performed for patients with a history of allergy to evaluate the effect of the induction of anesthesia with propofol against histamine release, skin reactions, hemodynamic changes and other clinical symptoms, while also comparing these parameters during the induction of anesthesia with midazolam-ketamine for patients with a history of allergy. SUBJECTS: We examined 40 patients undergoing oral surgery, who had a history of allergy and/or the percentage of eosinophils in the leukocytes was more than 3%. METHODS: Forty patients were randomly allocated into two groups and thus received either midazolam-ketamine (M-K group, n = 20) or fentanyl-propofol (propofol group, n = 20) for the induction of anesthesia. Venous blood samples (4 ml each) were obtained before induction as a control and at 0.5, 1, 3, 5 minutes after the administration of each induction agent, and then furthermore at 0.5, 1, 3, 5 minutes after tracheal intubation in order to measure the plasma histamine level by using the HPLC post-label system. In addition, the blood pressure and heart rate were also simultaneously recorded. Skin reactions were also evaluated by two anesthesiologists. RESULTS: The incidence of 50% histamine release during the induction of anesthesia with propofol occurred in 15% of the patients with a history of allergy. Sixteen patients out of 20 (80%) showed a decrease in the systolic blood pressure after the administration of propofol without any evidence of histamine release. The incidence of 50% histamine release, skin reactions and an increase in the heart rate between the two groups were not statistically significant after the administration of each anesthetic agent. Moreover, some patients also demonstrated histamine release after tracheal intubation. Hemodynamic changes after tracheal intubation showed a similar tendency in both groups. No significant difference was observed regarding the incidence of histamine release, skin reactions and hemodynamic changes between both groups after tracheal intubation. CONCLUSIONS: Propofol was found to show a similar incidence of histamine release during the induction of anesthesia using midazolam-ketamine, and thus was also found to be a useful induction agent against histamine release for patients with a history of allergy when hydroxizine was used as a premedication.     

Reversibility of the haemodynamic effects of anabolic steroids in rats

Summary The haemodynamic effects of 6 weeks nandrolone decanoate treatment (total dose 30 mg · kg^–1) (SG I,n=12) and their reversibility were studied in anaesthetised, open-chest male rats exposed to 5 min isoproterenol (2.5 g · kg^–1) and CaCl₂ (25.0 mg · kg^–1) loads. In SG I, the heart weight and its ratio to body weight were greater than in the untreated rats (CG I,n=13) (p<0.05 andp<0.01 respectively). The initial heart rate and the inotropic and chronotropic responses to isoproterenol were lower in SG I than in CG I (p<0.05 in all cases). Peripheral resistance decreased during both infusions in SG I but remained unaltered in CG I (p<0.05). 6 weeks after finishing anabolic steroid treatment (SG II,n=11), in the CaCl₂-test the ejection fraction (p<0.05) and stroke index were smaller than in control rats of the same age (CG II,n = 12). Mean aortic pressure was lower in SG II than in CG II. In the CaCl₂-test peripheral resistance was initially higher, but decreased during the infusion in SG II while it increased in CG II (p<0.05 in both cases). In conclusion, anabolic steroid treatment reversibly reduces the left ventricular response to isoproterenol. It decreases peripheral vascular tone during inotropic loads. Six weeks after the cessation of treatment, the pumping efficiency of the heart is reduced.     

Effect of fluid intake on renal function during exercise in the cold

Summary The effect of an imposed drinking discipline versus ad libitum drinking was studied on 21 healthy, well-trained volunteers, during a continuous 4.5-h march at an altitude of 1,700 m and an ambient temperature of 0° C, SD 1. Group I (n = 13) was instructed to drink 250 ml of warmed, artificially sweetened fluid every 30 min, whereas group II (n = 8) drank plain water ad libitum. The median fluid intake in group I was significantly higher than in group II (P < 0.0002). Serum urea and osmolality decreased during the march in group I (P < 0.05; P < 0.002, respectively) with no significant change in group II. In both groups, a similar increase in haemoglobin concentration concomitant with a reduction in calculated blood and plasma volume was observed after exercise and did not correlate with the state of hydration. Total urine volume, creatinine clearance, urea clearance and potassium excretion were significantly higher and urinary osmolality was lower in group I than in group II (P < 0.05). These results reflect a state of extreme voluntary dehydration in the control group when no fluid intake was obligatory. Thus, during exercise in the cold, under conditions similar to those in this study, a fluid intake of 150 ml · h^–1 should be maintained in order to keep a urinary flow of about 1 ml · kg^–1 · h^–1 and to achieve a good state of hydration.     

Sodium citrate and anaerobic performance: implications of dosage

Summary The use of sodium bicarbonate to improve anaerobic performance is well known but other buffering agents have been used with some success. Sodium citrate is one such substance which has been used but without the normal gastro-intestinal discomfort usually associated with sodium bicarbonate ingestion. The effects of five doses of sodium citrate (0.1 g·kg^–1 body mass, 0.2 g·kg^–1 body mass, 0.3 g·kg^–1 body mass, 0.4 g·kg^–1 body mass and 0.5 g·kg^–1 body mass) on anaerobic performance were studied in order to determine the minimal and most productive dose required for performance enhancement. A maximal test was performed for 1^–1, min on a cycle ergometer. Total work and peak power were measured at the end of the exercise period. Blood was drawn 1.5 h prior to the test session and measured for pH, partial pressure of carbon dioxide and concentrations of bicarbonate, base excess and lactate. In all but the control and placebo trials subjects then ingested one of five doses of sodium citrate which was contained in 400 ml of flavoured drink. Blood was again taken 90 min later and this was repeated after the completion of the exercise test. The greatest amount of work was completed in the trial with citrate given at 0.5 g·kg^–1 body mass (44.63 kJ, SD 1.5) and this was also true for peak power (1306 W, SD 75). The post-exercise blood lactate concentration was also highest during this trial 15.9 mmol·1^–1, SD 1.1. Post-exercise pH decreased significantly in all trials (P<0.0001) while the administration of the sodium citrate in all doses above 0.1 g·kg^–1 body mass significantly increased resting pH values. Blood bicarbonate concentrations also increased with dose in an almost linear fashion with the administration of sodium citrate. Bicarbonate increases were all significant, P<0.05 (citrate 0.1 g·kg^–1 body mass), P<0.01 (citrate 0.2 g·kg^–1 body mass, 0.3 g·kg^–1 body mass and 0.4 g·kg^–1 body mass) and P<0.005 (citrate 0.5 g·kg^–1 body mass). The administration of sodium citrate also significantly increased base excess values (citrate 0.1 g·kg^–1 body mass,P<0.01; 0.2 g·kg^–1body mass, P<0.001; 0.3 g·kg^–1 body mass, P<0.001; 0.4 g·kg^–1 body mass, P<0.001; 0.5 g·kg^–1 body mass, P<0.0001) above control and placebo values. All post-exercise base excess values were significantly lower than basal or pre-exercise values (P<0.0001). It was concluded that sodium citrate was an effective ergogenic aid for anaerobic performance of approximately 60-s duration, with the most effective of those dosages tested being 0.5 g·kg^–1 body mass.     

Systemic and renal hemodynamic effects of the AT1 receptor antagonist, ZD 7155, and the AT2 receptor antagonist, PD 123319, in conscious lambs

Experiments were carried out to investigate age- and dose-dependent effects of the selective AT₁ receptor antagonist, ZD 7155, and the selective AT₂ receptor antagonist, PD 123319, on systemic and renal hemodynamics in conscious, chronically instrumented lambs aged ∼1 and ∼6 weeks of postnatal life. Mean arterial pressure (MAP), mean venous pressure (MVP), and renal blood flow (RBF) were measured for 10 min before and for 120 min after ZD 7155, PD 123319, or vehicle. In both age groups, administration of ZD 7155 decreased renal vascular resistance (RVR) and increased RBF within 5 min. These responses lasted less than 90 min but were not dose-dependent. MAP decreased by 30 min after administration of ZD 7155 in both age groups at doses ≥400 μg kg⁻¹; the remaining decreased for up to 120 min, depending upon the dose. Pressor responses to angiotensin II (ANG II) were abolished within 5 min of administration of all doses of ZD 7155, at both 1- and 6 weeks. PD 123319 had no detectable effects on systemic or renal hemodynamics or on the pressor responses to ANG II. Therefore, under physiological conditions in conscious newborn animals, ANG II modulates both resting blood pressure and RVR through activation of AT₁ but not AT₂ receptors.