Guo Liang, Tabrizchi Reza
Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.
Eur J Pharmacol. 2008 May 31;586(1-3):266-74. doi: 10.1016/j.ejphar.2008.02.045. Epub 2008 Feb 26.
The arteriovenous fistula model of circulation can produce a high output and low peripheral resistance situation. Here, we have examined the effects of noradrenaline, vasopressin and sodium nitroprusside on cardiac index, mean arterial blood pressure, venous tone, resistance to venous return, arterial resistance, and blood volume in chronically shunted anaesthetized rats. The cardiac index of rats with chronic arteriovenous fistula (AVF) was significantly higher (36.65+/-2.28 ml/min per 100 g; (mean+/-S.E.M.; n=24) in comparison to sham-operated rats (20.04+/-0.86 ml/min per 100 g; mean+/-S.E.M.; n=8). Cardiac index did not significantly change during the infusion of noradrenaline (1.0, 3.0 and 10 microg/kg per min), vasopressin (10, 30, 100 ng/kg per min) or sodium nitroprusside (0.1, 0.3 and 1.0 microg/kg per min) compared to saline infusion in AVF animals. Infusion of noradrenaline significantly increased heart rate, dP/dt, mean circulatory filling pressure (Pmcf) and resistance to venous return without affecting mean arterial blood pressure when compared to saline infusion. Administration of vasopressin significantly increased dP/dt, mean arterial blood pressure, and Pmcf without affecting heart rate, resistance to venous return or arterial resistance compared to saline infusion. Infusion of sodium nitroprusside did not significantly affect any haemodynamic parameter measured when compared to saline infusion. The results indicate that the presence of chronic AVF alters responsiveness of the various segments of the circulatory system to vasoactive agents. Moreover, it produces a major impediment to overall changes that can normally be induced following the infusion of such agents.
动静脉瘘循环模型可产生高输出量和低外周阻力的情况。在此，我们研究了去甲肾上腺素、血管加压素和硝普钠对慢性分流麻醉大鼠的心指数、平均动脉血压、静脉张力、静脉回流阻力、动脉阻力和血容量的影响。与假手术大鼠（每100克20.04±0.86毫升/分钟；平均值±标准误；n = 8）相比，慢性动静脉瘘（AVF）大鼠的心指数显著更高（每100克36.65±2.28毫升/分钟；平均值±标准误；n = 24）。与在AVF动物中输注生理盐水相比，在输注去甲肾上腺素（每分钟1.0、3.0和10微克/千克）、血管加压素（每分钟10、30、100纳克/千克）或硝普钠（每分钟0.1、0.3和1.0微克/千克）期间，心指数没有显著变化。与输注生理盐水相比，输注去甲肾上腺素显著增加心率、dp/dt、平均循环充盈压（Pmcf）和静脉回流阻力，而不影响平均动脉血压。与输注生理盐水相比，给予血管加压素显著增加dp/dt、平均动脉血压和Pmcf，而不影响心率、静脉回流阻力或动脉阻力。与输注生理盐水相比，输注硝普钠对所测量的任何血流动力学参数均无显著影响。结果表明，慢性AVF的存在改变了循环系统各部分对血管活性药物的反应性。此外，它对通常在输注此类药物后可诱导的整体变化产生了主要阻碍。
