Hypotensive effect of push-pull gravitational stress occurs after autonomic blockade.
Hypotensive effect of push-pull gravitational stress occurs after autonomic blockade.
复制标题
自主神经封锁后会出现推拉重力应力的降压作用。
DOI：
10.1152/japplphysiol.00165.2003
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Sheriff,DonD
中科院分区：
文献类型：
--
作者：
Sheriff,DonD
The “push-pull” effect denotes the reduced tolerance to +Gz(hypergravity) when +Gzstress is preceded by exposure to hypogravity, i.e., fractional, zero, or negative Gz. Previous studies have implicated autonomic reflexes as a mechanism contributing to the push-pull effect. The purpose of this study was to test the hypothesis that nonautonomic mechanisms can cause a push-pull effect, by using eye-level blood pressure as a measure of G tolerance. The approach was to impose control (30 s of 30° head-up tilt) and push-pull (30 s of 30° head-up tilt immediately preceded by 10 s of -15° headdown tilt) gravitational stress after administration of hexamethonium (10 mg/kg) to inhibit autonomic ganglionic neurotransmission in four dogs. The animals were chronically instrumented with arterial and venous catheters, an ascending aortic blood flow transducer, ventricular pacing electrodes, and atrioventicular block. The animals were paced at 75 beats/min throughout the experiment. The animals were sedated with acepromazine and lightly restrained in lateral recumbency on a tilt table. After the onset of head-up tilt, the magnitude of the fall in eye-level blood pressure from baseline was -27.6 ± 2.3 and -37.9 ± 2.7 mmHg for the control and push-pull trials, respectively (P< 0.05). Cardiac output fell similarly in both conditions. Thus a push-pull effect attributable to a rise in total vascular conductance occurs when autonomic function is inhibited.
