Fig. 8.

Coupling of ET_A receptors to phospholipase C and adenylyl cyclase pathways. A,Left, Concentration dependence of ET-1 on InsP₃ production. A, Right, The lack of effects of pertussis toxin (PTX) on somatostatin (100 nm) and ET-1-induced (100 nm) InsP₃ production. B, Left, Concentration dependence of ET-1 on cAMP production. B, Right, Effects of pertussis toxin on somatostatin (100 nm) and ET-1-induced (100 nm) cAMP production. Cells were exposed to 250 ng/ml PTX overnight. The results shown are the mean ± SEM from sextuplicate incubation. The dotted lines indicate the EC₅₀ and IC₅₀ for the ET-1-induced increase in InsP₃ and the decrease in cAMP productions, respectively, derived from fitted logistic curves.