Effects of vasopressin on single Cl − channels in the apical membrane of distal nephron cells (A6)

Abstract

We have investigated how two types of Cl − channels found in sodium transporting epithelium are regulated by arginine vasopressin (AVP). A6 cells cultured on permeable supports for 10 to 14 days have two types of Cl − channels in the apical membrane that have single channel conductances of 3 and 8 pS. In cells without AVP pretreatment, the 3 pS Cl − channel was more frequently observed than the 8 pS Cl − channel. AVP increased the open probability ( P o ) and single channel conductance of the 3 pS Cl − channel without significantly changing the P o or conductance of the 8 pS Cl − channel. On the other hand, AVP did not affect the number of the 3 pS Cl − channel, but increased the number of 8 pS Cl − channels. These observations suggest that AVP has two different pathways to increase apical membrane chloride conductance in distal nephron A6 cells; i.e., (1) increases the P o and single channel conductance of 3 pS Cl − channels and (2) increases the number of 8 pS Cl − channels.