In vivo dose-response characteristics of endothelin-1: studies on rat saphenous vein

Microangiometric studies were made in vivo on rat saphenous vein to obtain dose-response contraction curves with endothelin-1. During superfusion of the drug, threshold concentrations were found to be in the range of 4 x 10(-11) -4 x 10(-10) moles/lit, maximal concentrations were about 4 x 10(-8) moles/lit. These values are close to published in vitro threshold values. During intravascular administration of the drug contraction could be observed in response to a dose as small as 4.37 femtomoles/s. The data presented show that characteristic dose response curves resembling those found in vitro can be recorded in vivo with endothelin on appropriate vascular preparata. The rat in situ saphenous vein microangiometric technic can be used for delicate pharmacologic examination of venoactive substances in vivo.