Mechanism of adrenergic stimulation of anion secretion in cultured rat epididymal epithelium.

Primary monolayer cultures of the epithelial cells from the rat cauda epididymidis had a basal transepithelial potential of 1.24 +/- 0.11 mV, apical side negative, a short-circuit current (SCC) of 2.42 +/- 0.17 microA/cm2, and a transepithelial resistance of 503 +/- 29.6 omega/cm2. Epinephrine (0.23 microM) added to the basolateral side caused a rise in the SCC (inward flowing) that was partially reversed by addition of amiloride, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS), bumetanide, and acetazolamide to the basolateral side. In the absence of Cl or HCO3, the SCC response to epinephrine was reduced by 65 and 66%, respectively. Removal of K reduced the SCC response by 40%, whereas Na removal completely abolished it. A23187 and phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), stimulated the SCC when added to the apical side. Addition of the Cl channel blockers, anthracene-9-carboxylate and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) to the apical side reduced the SCC in a dose-dependent manner. It is concluded that anion secretion by the epididymis shares common mechanisms with other Cl-secreting epithelia.