Gardiner S M, Bennett T
Department of Physiology and Pharmacology, Medical School, Queen's Medical Centre, Nottingham, United Kingdom.
Am J Physiol. 1988 Oct;255(4 Pt 2):H813-24. doi: 10.1152/ajpheart.1988.255.4.H813.
Changes in blood pressure and renal, mesenteric, and hindquarters vascular resistances were measured in conscious Long-Evans and Brattleboro (vasopressin-deficient) rats in response to sequential, continuous administrations of prazosin and idazoxan in the absence or presence of ICI 118551 (beta 2-adrenoceptor antagonist) or propranolol. The large transient hypotensions elicited by prazosin and, subsequently, by idazoxan were associated with renal and hindquarters vasodilatations in both strains of rat. In Brattleboro rats, prazosin also elicited mesenteric vasodilatation. Pretreatment with ICI 118551 reduced the initial hypotensive effects and hindquarters vasodilatations elicited by prazosin and idazoxan, but the hemodynamic effects of prazosin were not significantly affected by propranolol. These results are consistent with propranolol antagonizing beta 1-adrenoceptor-mediated effects on the heart and the renin-angiotensin system that act to offset a beta 2-adrenoceptor-mediated vasodilatation, which contributes to the effects elicited by alpha-adrenoceptor antagonism. Hemodynamic responses to captopril and d(CH2)5DAVP (in Long-Evans rats) in the presence of adrenoceptor antagonists were consistent with a major cardiovascular role of the renin-angiotensin system and a less overt role of vasopressin until the latter system was blocked.
在清醒的Long-Evans大鼠和Brattleboro（抗利尿激素缺乏）大鼠中，测量了血压以及肾、肠系膜和后肢血管阻力的变化，这些变化是在给予哌唑嗪和咪唑克生连续给药时，在不存在或存在ICI 118551（β2肾上腺素能受体拮抗剂）或普萘洛尔的情况下产生的。哌唑嗪以及随后的咪唑克生引起的大幅度短暂性低血压与两种品系大鼠的肾和后肢血管舒张有关。在Brattleboro大鼠中，哌唑嗪还引起肠系膜血管舒张。用ICI 118551预处理可降低哌唑嗪和咪唑克生引起的初始降压作用和后肢血管舒张，但哌唑嗪的血流动力学效应未受到普萘洛尔的显著影响。这些结果与普萘洛尔拮抗β1肾上腺素能受体介导的对心脏和肾素-血管紧张素系统的作用一致，这些作用可抵消β2肾上腺素能受体介导的血管舒张，而β2肾上腺素能受体介导的血管舒张有助于α肾上腺素能受体拮抗作用所引发的效应。在存在肾上腺素能受体拮抗剂的情况下，对卡托普利和d(CH2)5DAVP（在Long-Evans大鼠中）的血流动力学反应与肾素-血管紧张素系统的主要心血管作用以及抗利尿激素不太明显的作用一致，直到后者系统被阻断。
