Prostaglandin E2 activates clusters of apical Cl- channels in principal cells via a cyclic adenosine monophosphate-dependent pathway.

Abstract

IntroductionWe examined cell-attached patches on principal cells of primary cultured, rabbit cortical collecting tubules. Under basal conditions, apical 9-pS Cl --selective channels were observed in 9% of patches (11 / With its low baseline frequency and Ere, near resting membrane potential, this channel would not contribute significantly to transcellular Cl-flux under basal conditions. (e) However, cAMP-producing agonists (i.e., PGE2, arginine vasopressin) would increase apical C1-transport with the direction determined by the apical membrane potential. (J. Clin. Invest. 1994. 93:829-837.)

Anion secretion by the inner medullary collecting duct. Evidence for involvement of the cystic fibrosis transmembrane conductance regulator.

“…In addition to these data from intact tubules, there is evidence that CFTRlike Cl-channels are present in the apical membrane of distal nephron cells. Cl -channels with the appropriate single-channel characteristics have been identified in A6 cells (28), primary cultures of rabbit cortical collecting duct (29), and primary cultures of rabbit early distal convoluted tubule (30). We point out that other kinds of Cl-channels have been demonstrated in the apical membrane of distal nephron epithelial cells (28,31).…”

“…The reason that activation of apical membrane Cl-channels could effect either net secretion or absorption is that the electrochemical driving force for Cl-across the apical membrane under "normal" conditions is near 0 (29). The magnitude of the apical membrane voltage is a major determinant of the direction of the net Cl -movement.…”

Mouse cystic fibrosis transmembrane conductance regulator forms cAMP-PKA–regulated apical chloride channels in cortical collecting duct

“…The PKA-stimulated currents have been suggested to be due to CFTR, on the basis of expression of CFTR mRNA and/or protein in these cultured cells, the absence of Cl − currents in cells cultured from CFTR null mice (14), and an anion permeability sequence compatible with CFTR in M1 cells (15). A small apical Cl − conductance has also been found in primary cultures of rabbit principal cells (16,17), and single Cl − channel activity exhibited some of the characteristics of human CFTR. Although these studies suggest that cultured renal principal cells may express CFTR, the presence of CFTR Cl − single-channel activity in native renal tubule epithelial cells and the role of any such channel activity in kidney function have not been established (2).…”

Inhibition of a small‐conductance cAMP‐dependent Cl‐ channel in the mouse thick ascending limb at low internal pH.

“…Therefore, pH sensitivity is another (but not conclusive) indication that the small-conductance Clchannel discussed here is distinct from the CFTR. Cl-channels having properties similar to those of the CTAL channel have been found in the basolateral membranes of the rabbit proximal tubule (Segal, Geibel & Boulpaep, 1993) and in apical membranes of cultured cells from distal convoluted tubule (Poncet, Tauc, Bidet & Poujeol, 1994) and cortical collecting tubule (Ling, Kokko & Eaton, 1994). There is no evidence that these channels are also sensitive to internal pH.…”