Regulation of collecting duct Na+ reabsorption by ANP 31-67

Abstract

1. The bulk of studies of the actions of atrial natriuretic peptides (ANP) have focussed on the carboxyterminal derivative (ANP 99-126) of the prohormone (ANP 1-126), but recent evidence indicates that an additional peptide derived from ANP 1-126, namely, ANP 31-67 also circulates, and has natriuretic actions. 2. The effects of ANP 31-67 on inner medullary collecting duct (IMCD) Na+ transport have been examined in freshly prepared suspensions of rabbit IMCD cells. Like ANP 99-126, ANP 31-67 reduces Na+ transport in these cells. 3. However, unlike ANP 99-126, this effect is not mediated by cGMP, and does not result from inhibition of apical Na+ channels. Rather, ANP 31-67 inhibits basolateral Na/K-ATPase, probably via the stimulation of PGE2 synthesis. 4. These results are discussed in the context of other natriuretic substances (interleukin 1 and endothelin), which also inhibit Na+ reabsorption by PGE2-mediated inhibition of Na/K-ATPase.