Fujie M, Ichikawa S, Sakamaki T, Kogure M, Fujita H, Nakamura T, Murata K
Second Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Japan.
Life Sci. 1988;42(7):759-67. doi: 10.1016/0024-3205(88)90648-0.
We examined the interrelationships between the pressor response to the administration of norepinephrine and arginine vasopressin and baroreflex function in rats with hypertension of two days' duration induced by heminephrectomy and a clip placed on the right renal artery (2-day clipped rats). Mean arterial pressure was higher in the 2-day clipped rats than in heminephrectomized rats without clips (sham-operated rats). The pressor response in the 2-day clipped rats to both agents increased as compared to the sham-operated rats. This hyperresponsiveness was attenuated by administering an angiotensin II antagonist, [1-Sar, 8-Ile] angiotensin II. Baroreflex sensitivity was studied by measuring changes in arterial pressure and pulse interval in response to the injection of phenylephrine. Baroreflex sensitivity was not decreased but markedly increased in the 2-day clipped rats and unaffected by infusing the angiotensin II antagonist. These results provide evidence that 1) in the 2-day clipped rats there are exaggerated pressor responses to vasoconstrictors; 2) the hyperresponsiveness is not causally related to the change of baroreflex sensitivity; and 3) angiotensin II plays a significant role in the increased pressor responses; however, the baroreflex mechanism is not involved in attenuation of the hyperresponsiveness by the angiotensin II antagonist.
我们研究了在由半肾切除和右肾动脉夹闭诱导的为期两天的高血压大鼠（2日夹闭大鼠）中，去甲肾上腺素和精氨酸加压素给药后的升压反应与压力反射功能之间的相互关系。2日夹闭大鼠的平均动脉压高于未夹闭的半肾切除大鼠（假手术大鼠）。与假手术大鼠相比，2日夹闭大鼠对这两种药物的升压反应均增加。通过给予血管紧张素II拮抗剂[1- Sar，8- Ile]血管紧张素II，这种高反应性得到减弱。通过测量注射去氧肾上腺素后动脉压和脉搏间期的变化来研究压力反射敏感性。2日夹闭大鼠的压力反射敏感性并未降低，反而显著增加，且不受血管紧张素II拮抗剂输注的影响。这些结果证明：1）在2日夹闭大鼠中，对血管收缩剂的升压反应增强；2）高反应性与压力反射敏感性的变化无因果关系；3）血管紧张素II在升压反应增加中起重要作用；然而，压力反射机制不参与血管紧张素II拮抗剂对高反应性的减弱作用。
