Regulation of renin release by connexin 43 in As 4.1 cell line

Gap junction channels facilitate chemical and electrical communication between adjacent cells. Gap junction protein, connexin (Cx), is expressed in the endothelial cells of vessels, glomerulus, and renin-secreting cells of the kidney. The purpose of this study was to investigate the role of Cx in renin release using Cx-overexpressing As 4.1 cells. The adenovirus-induced Cx overexpression was conducted by using recombinant adenovirus containing the cDNA encoding Cx37, Cx40, Cx43 (Ad-Cx), and β-galactosidase (Ad-β-gal). In 40-overexpressing cells, basal renin release increased in a time-dependent manner but it was significantly lower than that in Ad-β-gal-treated cells. In Cx37- and Cx43-overexpressing cells, basal renin release was increased in a time-dependent manner, which was not different from control cells. 18-β glycyrrhetinic acid (GA), a gap junction blocker, stimulated renin release dose-dependently and increased intracellular Ca²⁺ in both Cx43-overexpressing cells and control cells. However, no significant differences were observed. An increase in renin release by 3,4,5-trimethoxybenzoic acid 8-(diethylamino)-octyl ester, a putative antagonist of Ca²⁺ release from intracellular sequestration sites, was also similar between two groups. These results suggest that Cx43 may unlikely alter the regulation of renin release and intracellular Ca²⁺ by gap junction blocker in As 4.1 cells.