Busatto P A, Jurkiewicz A
Br J Pharmacol. 1985 Aug;85(4):737-46. doi: 10.1111/j.1476-5381.1985.tb11071.x.
The effects of noradrenaline and barium chloride were studied in the rat isolated vas deferens by perfusion of drugs either externally or through the lumen of the organ. Two effects were recorded simultaneously in the same preparation: (a) isometric contractions, due to the tension elicited by drugs on the external (longitudinal) smooth muscle layer and (b) pressure of internal perfusion, due to contractions of the internal (circular) smooth muscle layer. It was found with the longitudinal muscle that: (a) the potency, expressed as pD2 values, and the maximum response to noradrenaline were lower if the drug was perfused internally rather than externally; (b) the differences in maximum effects were pronounced on the prostatic half but were not observed on the epididymal half; (c) the maximum response obtained by internal perfusion could be increased by simultaneously adding the same dose of drug externally; (d) when barium chloride was used instead of noradrenaline no significant differences were observed on pD2 values, but differences on maximal responses were similar to that observed for noradrenaline; (e) it was possible to block completely the effect of internal or external noradrenaline on the longitudinal muscle, by perfusing external phenoxybenzamine. In these conditions the responses of the circular muscle to the agonist were only partly blocked. With the circular muscle, the differences related to internal and external perfusion were less marked than in the longitudinal muscle. However, unlike the latter, the circular layer was slightly more sensitive to drugs applied internally, in relation to pD2 values. It is suggested that the difference in pD2 values may be due to the removal of noradrenaline by the neuronal uptake process, whereas the difference in maximal effect is due to the inaccessibility of part of the receptor population when drugs are added through the lumen.
通过在大鼠离体输精管外部或通过器官管腔灌注药物，研究了去甲肾上腺素和氯化钡的作用。在同一制剂中同时记录两种效应：(a) 等长收缩，这是由于药物对外部（纵向）平滑肌层产生的张力引起的；(b) 内部灌注压力，这是由于内部（环形）平滑肌层的收缩引起的。对于纵向肌，发现：(a) 如果药物通过内部灌注而非外部灌注，以pD2值表示的效力以及对去甲肾上腺素的最大反应较低；(b) 最大效应的差异在前列腺半段很明显，但在附睾半段未观察到；(c) 通过同时在外部添加相同剂量的药物，可以增加内部灌注获得的最大反应；(d) 当使用氯化钡代替去甲肾上腺素时，pD2值未观察到显著差异，但最大反应的差异与去甲肾上腺素观察到的相似；(e) 通过灌注外部酚苄明，可以完全阻断内部或外部去甲肾上腺素对纵向肌的作用。在这些条件下，环形肌对激动剂的反应仅被部分阻断。对于环形肌，与内部和外部灌注相关的差异不如纵向肌明显。然而，与纵向肌不同，就pD2值而言，环形层对内部应用的药物略更敏感。有人认为，pD2值的差异可能是由于神经元摄取过程去除了去甲肾上腺素，而最大效应的差异是由于通过管腔添加药物时部分受体群体无法接近所致。
