A HUMAN BRONCHIAL EPITHELIAL-CELL LINE RELEASES ARGININE-VASOPRESSIN - INVOLVEMENT OF CA2-ACTIVATED K+ CHANNELS()

To determine whether airway epithelium releases arginine vasopressin ( AVP) and, if so, what the mechanism of the release is, we studied cult ured human bronchial epithelial cell line, 16-HBE cells, in vitro. The cells spontaneously released small but significant amounts of AVP, an d this release was dose dependently increased by platelet-activating f actor (PAF) or bradykinin (BK). The PAF- and BK-induced AVP release wa s inhibited by 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate, a phosph olipase C inhibitor, and thapsigargin but not by Ca2+-free solution. P retreatment with the big conductance Ca2+-activated K+ channel blocker iberiotoxin attenuated the stimulated release of AVP, whereas apamin and glibenclamide were without effect. These results suggest that huma n bronchial epithelial cells release AVP and that the release may be s timulated by phospholipase C activation, mobilization of Ca2+ from int ernal stores and the concomitant activation of big conductance Ca2+-ac tivated K+ channels. (C) 1998 Elsevier Science B.V.