REGULATION OF NA-K-CL COTRANSPORT, NA,K-ADENOSINE TRIPHOSPHATASE, AND NA/H EXCHANGER IN HUMAN NEUROBLASTOMA NB-OK-1 CELLS BY ATRIAL-NATRIURETIC-PEPTIDE

The occupancy of atrial natriuretic peptide (ANP) receptors of the ANP(A) type in human neuroblastoma NB-OK-1 cells elevates cGMP. In this study, ANP concentrations of 10 nM or more increased total K+ uptake. Data obtained in the presence of bumetanide and/or ouabain demonstrated that 1 muM ANP induced a primary stimulation (by 82%) of Na-K-Cl cotransport and a subsequent indirect stimulation (by 15%) of Na,K-ATPase. ANP also inhibited Na/H exchange through an amiloride-sensitive mechanism, as shown by intracellular pH measurement in cells challenged or not by an acid or alkaline load. (Bu)2cGMP mimicked all ANP effects, suggesting that ANP acted through a cGMP-dependent mechanism.