Interaction between vasopressin and endothelin in renal papillary tubules: uncoupling following cell isolation and culture.

1. In freshly prepared rat renal papillary tubules, endothelin-related peptides inhibited the vasopressin-stimulated accumulation of cAMP. No inhibition was observed when tubules were cultured overnight ex vivo. 2. Endothelin-1, endothelin-3 and sarafatoxin S6b had similar potencies as inhibitors of cAMP accumulation, indicating an endothelin (ETb) receptor. 3. These results demonstrate an interaction between ETb receptors and vasopressin receptors at the level of their signal transduction pathways, and show that this relationship is lost following cell culture.