Borić M P, Donoso V, Fournier A, St Pierre S, Huidobro-Toro J P
Departamento de Fisiologia, FBBCC, Universidad Católica de Chile, Santiago.
Eur J Pharmacol. 1990 Nov 6;190(1-2):123-33. doi: 10.1016/0014-2999(90)94119-i.
Superfusion of the cheek pouch with 0.1-10 nM endothelin (E) produced a concentration-related reduction in the clearance of 22Na+ used as an indicator of microvascular plasma flow. The median effective concentration was about 2 nM. The time course of E action was also concentration related. Superfusion with 10 nM E for 10 min caused a greater than 80% reduction in 22Na+ clearance; the rate at which the action of E started was significantly faster than the rate at which its action ended. Recovery did not exceed 70% even though the tissue was superfused with drug-free buffer for 90 min. The E-induced reduction in 22Na+ clearance was associated with vasoconstriction, as determined by intravital microscopy. Arterioles of 4th branching order were more sensitive to E action than arterioles of 1st or 2nd order; however, the constriction lasted considerably longer in the latter vessels. E-induced venular constriction followed a pattern analogous to that of arterioles of the same category, with the exception that the finer venules responded the least. Pretreatment of the cheek pouch with 300 nM nifedipine diminished but did not abolish the 1 nM E-induced reduction in 22Na+ clearance, and the recovery of clearance upon E washout was not accelerated by nifedipine.
用0.1 - 10 nM内皮素（E）灌注颊囊，会使作为微血管血浆流量指标的22Na+清除率呈浓度依赖性降低。半数有效浓度约为2 nM。E作用的时间进程也与浓度相关。用10 nM E灌注10分钟导致22Na+清除率降低超过80%；E作用开始的速率明显快于其作用结束的速率。即使将组织用无药缓冲液灌注90分钟，恢复也不超过70%。通过活体显微镜检查确定，E诱导的22Na+清除率降低与血管收缩有关。四级分支的小动脉比一级或二级小动脉对E作用更敏感；然而，后一类血管中的收缩持续时间长得多。E诱导的小静脉收缩遵循与同一类小动脉类似的模式，不同的是最细的小静脉反应最小。用300 nM硝苯地平预处理颊囊可减轻但不能消除1 nM E诱导的22Na+清除率降低，并且硝苯地平不会加速E洗脱后清除率的恢复。
