Vasopressin stimulates long‐term net chloride secretion in cortical collecting duct cells

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Abstract
The classical short‐term effect (within minutes) of arginine vasopressin (AVP) consists in increasing sodium, chloride and water transport in kidney cells. More recently, long‐term actions (several hours) of the hormone have been evidenced on water and sodium fluxes, due to transcriptional enhancement in the expression of their transporters. The present study demonstrates that AVP is also responsible for a long‐term increase in net chloride secretion. In the RCCD1 rat cortical collecting duct cell line, 10−8 M AVP induced, after several hours, an increase in net 36Cl− secretion. This delayed effect of AVP was inhibited by basal addition of 10−4 M bumetanide and apical addition of 10−4 M glibenclamide, suggesting chloride entry at the basal membrane through a Na+/K+/2Cl− and apical secretion through a chloride conductance. An original acute cell permeabilization method was developed to allow for entry of antibodies directed against the regulatory region (R) of the cystic fibrosis transmembrane regulator (CFTR) into the cells. This procedure led to a complete and specific blocking of the long‐term net chloride secretion induced by AVP. Finally, it was observed that CFTR transcripts steady‐state level was significantly increased by AVP treatment. Besides the well‐documented short‐term effect of AVP on chloride transport, these results provide evidence that in RCCD1 cells, AVP induces a delayed increase in transepithelial net chloride secretion that is mediated by a Na+/K+/2Cl− co‐transporter and CFTR.