Stephens G A, Shirer H W, Trank J W, Goetz K L
Am J Physiol. 1983 Apr;244(4):R544-52. doi: 10.1152/ajpregu.1983.244.4.R544.
Attempts were made to stimulate an arterial baroreceptor reflex in anesthetized and conscious pond turtles. In turtles anesthetized with either alpha-chloralose or pentobarbital, occlusion of the ascending or descending aortas produced no reflex heart rate (HR) changes. In pentobarbital-anesthetized turtles, direct electrical or mechanical stimulation of potential baroreceptor sites along the central aortic arches and carotid arteries produced no significant changes in either HR or blood pressure (BP). Occlusion of the common carotid arteries also produced no HR or BP changes. Intravenously administered nitroglycerin lowered BP but caused no reflex tachycardia in anesthetized turtles. Phenylephrine and angiotensin elevated BP in the anesthetized turtle but caused no reflex bradycardia. In conscious turtles phenylephrine increased BP and nitroglycerin decreased BP. Neither response produced a statistically significant HR change, although HR tended to decrease transiently with phenylephrine and increase with nitroglycerin. These HR changes were abolished by atropine. Rapid intra-arterial infusion of 6% dextran transiently raised BP but caused no reflex bradycardia. These experiments suggest that cardiovascular regulation in the turtle is accomplished without a major contribution from arterial baroreceptor reflexes.
研究人员试图在麻醉和清醒的池龟中刺激动脉压力感受器反射。在用α-氯醛糖或戊巴比妥麻醉的海龟中，升主动脉或降主动脉的闭塞未引起反射性心率（HR）变化。在戊巴比妥麻醉的海龟中，沿中央主动脉弓和颈动脉对潜在压力感受器部位进行直接电刺激或机械刺激，HR和血压（BP）均未出现显著变化。颈总动脉的闭塞也未引起HR或BP变化。静脉注射硝酸甘油可降低BP，但在麻醉的海龟中未引起反射性心动过速。去氧肾上腺素和血管紧张素可使麻醉海龟的BP升高，但未引起反射性心动过缓。在清醒的海龟中，去氧肾上腺素使BP升高，硝酸甘油使BP降低。尽管HR在使用去氧肾上腺素时往往会短暂下降，在使用硝酸甘油时会升高，但两种反应均未产生统计学上显著的HR变化。这些HR变化可被阿托品消除。快速动脉内输注6%右旋糖酐可使BP短暂升高，但未引起反射性心动过缓。这些实验表明，海龟的心血管调节在没有动脉压力感受器反射的主要参与下即可完成。
