Machado B H, Salgado H C
Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil.
Braz J Med Biol Res. 1990;23(3-4):337-41.
We investigated the effect of the infusion of angiotensin II on intrinsic heart rate in rats with sino-aortic deafferentation. Sino-aortic deafferentated (SAD) rats studied 48 h after surgery presented significant tachycardia when compared with sham-operated rats (426 +/- 16 vs 338 +/- 6 bpm), but no change in intrinsic heart rate (369 +/- 9 vs 369 +/- 11 bpm). Infusion of angiotensin II into the SAD group 48 h after deafferentation did not produce an additional increase in heart rate (423 +/- 16 vs 426 +/- 16 bpm) or a change in intrinsic heart rate (369 +/- 11 vs 369 +/- 9 bpm) when compared with sham-operated rats submitted to saline infusion. Intravenous (iv) infusion of angiotensin II into sham-operated rats produced a significant increase in both heart rate (381 +/- 12 vs 338 +/- 6 bpm) and intrinsic heart rate (427 +/- 9 vs 369 +/- 11 bpm). These data indicate that a) tachycardia after SAD is not associated with an increase in intrinsic heart rate, b) in sham-operated rats, the tachycardia occurring after angiotensin II infusion is associated with an increase in intrinsic heart rate, and c) angiotensin II infusion does not alter the intrinsic heart rate of rats tested 48 h after sino-aortic deafferentation. We conclude that the increase in intrinsic heart rate caused by angiotensin II in conscious rats depends on the integrity of the baroreceptor reflex.
我们研究了在去窦主动脉神经支配的大鼠中输注血管紧张素II对固有心率的影响。与假手术大鼠相比，术后48小时研究的去窦主动脉神经支配（SAD）大鼠出现明显的心动过速（426±16对338±6次/分钟），但固有心率无变化（369±9对369±11次/分钟）。在去神经支配后48小时向SAD组输注血管紧张素II，与输注生理盐水的假手术大鼠相比，心率没有进一步增加（423±16对426±16次/分钟），固有心率也没有变化（369±11对369±9次/分钟）。向假手术大鼠静脉内（iv）输注血管紧张素II可使心率（381±12对338±6次/分钟）和固有心率（427±9对369±11次/分钟）均显著增加。这些数据表明：a）SAD后的心动过速与固有心率增加无关；b）在假手术大鼠中，血管紧张素II输注后出现的心动过速与固有心率增加有关；c）血管紧张素II输注不会改变去窦主动脉神经支配后48小时测试的大鼠的固有心率。我们得出结论，血管紧张素II在清醒大鼠中引起的固有心率增加取决于压力感受器反射的完整性。
