Cellular origin and hormonal regulation of K+-ATPase activities sensitive to Sch-28080 in rat collecting duct

Abstract

Rat collecting ducts exhibit type I or type III K+-ATPase activities when animals are fed a normal (NK) or a K+-depleted diet (LK). This study aimed at determining functionally the cell origin of these two K+-ATPases. For this purpose, we searched for an effect on K+-ATPases of hormones that trigger cAMP production in a cell-specific fashion. The effects of 1-deamino-8-d-arginine vasopressin (dD-AVP), calcitonin, and isoproterenol in principal cells, α-intercalated cells, and β-intercalated cells of cortical collecting duct (CCD), respectively, and of dD-AVP and glucagon in principal and α-intercalated cells of outer medullary collecting duct (OMCD), respectively, were examined. In CCDs, K+-ATPase was stimulated by calcitonin and isoproterenol in NK rats (type I K+-ATPase) and by dD-AVP in LK rats (type III K+-ATPase). In OMCDs, dD-AVP and glucagon stimulated type III but not type I K+-ATPase. These hormone effects were mimicked by the cAMP-permeant analog dibutyryl-cAMP. In conclusion, in NK rats, cAMP stimulates type I K+-ATPase activity in α- and β-intercalated CCD cells, whereas in LK rats it stimulates type III K+-ATPase in principal cells of both CCD and OMCD and in OMCD intercalated cells.