Rohmeiss P, Photiadis J, Rohmeiss S, Unger T
Department of Pharmacology, University of Heidelberg, Federal Republic of Germany.
Am J Physiol. 1990 Feb;258(2 Pt 2):H337-46. doi: 10.1152/ajpheart.1990.258.2.H337.
We investigated hemodynamic actions of endothelin (ET) in conscious rats. Intravenous injections of ET produced dose-dependent biphasic blood pressure (MAP) responses: initial decreases of up to 84 +/- 11 s were followed by increases of up to 1-h duration. Corresponding responses in cardiac output (CO), heart rate, and efferent splanchnic nerve activity were reciprocal to changes in MAP. Mesenteric blood flow showed an immediate and sustained decrease. Compared with equidepressor doses of sodium nitroprusside (NNP), ET produced a markedly different regional hemodynamic response pattern during the initial depressor phase. Compared with equipressor doses of the alpha-adrenoceptor agonist methoxamine, ET produced significantly greater vasoconstriction in hindlimb and renal vascular bed during pressor phase. ET-induced changes in CO were significantly greater than the respective CO responses to NNP and methoxamine in intact animals and following cardiac autonomic blockade with atenolol and methscopolamine. ET has vasodilator and vasoconstrictor properties that induce a unique hemodynamic response pattern on intravenous injection. Persistence of ET-induced changes in CO following cardiac autonomic blockade suggests direct cardiostimulatory actions of the peptide during depressor phase as well as direct cardiodepressant actions during pressor phase.
我们研究了内皮素（ET）在清醒大鼠中的血流动力学作用。静脉注射ET可产生剂量依赖性双相血压（MAP）反应：最初血压下降持续长达84±11秒，随后血压升高持续长达1小时。心输出量（CO）、心率和内脏传出神经活动的相应反应与MAP的变化相反。肠系膜血流量立即且持续减少。与等效降压剂量的硝普钠（NNP）相比，ET在最初的降压阶段产生明显不同的局部血流动力学反应模式。与等效升压剂量的α-肾上腺素能受体激动剂甲氧明相比，ET在升压阶段在后肢和肾血管床产生明显更强的血管收缩作用。在完整动物中以及用阿替洛尔和甲基东莨菪碱进行心脏自主神经阻滞后，ET诱导的CO变化明显大于对NNP和甲氧明各自的CO反应。ET具有血管舒张和血管收缩特性，静脉注射时可诱导独特的血流动力学反应模式。心脏自主神经阻滞后ET诱导的CO变化持续存在，提示该肽在降压阶段有直接的心脏刺激作用，在升压阶段有直接的心脏抑制作用。
