Stimulation by cGMP of apical Na+ channel and cation channels in toad urinary bladder

MER. Stimulation by cGMP of apical Na channels and cation channels in toad urinary bladder. Am. J. Physiol. 260 (Cell Physiol. 29): C234-C241, 1991.-The effects of %bromoguano-sine 3’,5’-cyclic monophosphate (8BrcGMP) on apical mem-brane cation conductances in the toad urinary bladder were investigated. 8-BrcGMP (1 mM) added to the serosal solution increased the amiloride-sensitive short-circuit current (1& after a delay of 5 min to a steady-state value 1.8 times that of controls achieved after 30 min. Similar effects were seen when the bladders were bathed on the serosal side with a normal NaCl Ringer solution and with a high-K sucrose solution to depolarize the basolateral membrane. Under the latter condi-tions, the amiloride-sensitive transepithelial conductance in-crease & in para\\el with the short-circuit current, inhicating stimulation of apical membrane Na channels. The threshol