Yamamoto R, Cline W H
Department of Pharmacology, Southern Illinois University, School of Medicine, Springfield.
J Pharmacol Exp Ther. 1988 Mar;244(3):905-11.
The overflow of endogenous norepinephrine (NE) from the mesenteric vasculature of the isolated mesentery of Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) was determined in response to periarterial nerve stimulation (PNS) before and after pretreatment with propranolol or yohimbine. Propranolol pretreatment did not significantly alter spontaneous NE overflow, total NE overflow, NE overflow/stimulus or fractional NE overflow in either WKY or SHR mesenteric vascular preparations at any of the PNS frequencies used. Yohimbine pretreatment did not significantly alter spontaneous NE overflow but did significantly increase total NE overflow, NE overflow/stimulus and fractional NE overflow at all PNS frequencies used in both WKY and SHR preparations. The magnitude of the effect of yohimbine on NE overflow/stimulus did not differ between WKY and SHR over the range of PNS frequencies used. The lack of effect of propranolol on NE overflow suggests that corelease of epinephrine is not sufficient to activate beta adrenergic receptor-mediated modulation of noradrenergic neurotransmission in either WKY or SHR mesenteric vascular preparations under the in vitro study conditions used. However, the effects of yohimbine indicate that prejunctional alpha-2 adrenergic receptor-mediated inhibition of noradrenergic neurotransmission is operative in both WKY and SHR mesenteric vascular preparations. These effects of yohimbine also suggest that no significant differences exist between the functional level of prejunctional alpha-2 adrenergic receptor-mediated autoinhibitory modulation of noradrenergic neurotransmission in mesenteric vascular preparations from adult WKY and SHR under the in vitro study conditions used.
在使用普萘洛尔或育亨宾预处理前后，测定了Wistar Kyoto大鼠（WKY）和自发性高血压大鼠（SHR）离体肠系膜的肠系膜血管中内源性去甲肾上腺素（NE）的溢出情况，以响应动脉周围神经刺激（PNS）。在WKY或SHR肠系膜血管制剂中，使用任何PNS频率时，普萘洛尔预处理均未显著改变自发性NE溢出、总NE溢出、NE溢出/刺激或NE溢出分数。育亨宾预处理未显著改变自发性NE溢出，但在WKY和SHR制剂中使用的所有PNS频率下，均显著增加了总NE溢出、NE溢出/刺激和NE溢出分数。在使用的PNS频率范围内，育亨宾对NE溢出/刺激的影响程度在WKY和SHR之间没有差异。普萘洛尔对NE溢出缺乏影响表明，在所用的体外研究条件下，肾上腺素的共释放不足以激活WKY或SHR肠系膜血管制剂中β肾上腺素能受体介导去甲肾上腺素能神经传递的调节。然而，育亨宾的作用表明，在WKY和SHR肠系膜血管制剂中，节前α-2肾上腺素能受体介导的去甲肾上腺素能神经传递抑制作用是有效的。育亨宾的这些作用还表明，在所用的体外研究条件下，成年WKY和SHR肠系膜血管制剂中，节前α-2肾上腺素能受体介导的去甲肾上腺素能神经传递自抑制调节的功能水平之间不存在显著差异。
