REGULATED ANION SECRETION IN CULTURED EPITHELIA FROM SERTOLI CELLS OFIMMATURE RATS

1. Cultured epithelia of Sertoli cells from prepubertal rats were grow n on Matrigel-coated millipore filters for short-circuit current (I,,) measurements. Under basal conditions, these epithelia exhibited a 'ze ro' transepithelial potential difference, a 'zero' short-circuit curre nt and a transepithelial resistance of 60 Omega cm(2). 2. Forskolin (1 00 mu M) and 8-(4-chlorophenylthio)-cAMP (cpt-cAMP) (100 mu M) added t o the apical side stimulated the I-sc (forskolin, peak Delta I-sc = 1. 32 +/- 0.16 mu A cm(-1); cpt-cAMP, peak Delta I-sc = 0.88 +/- 0.16 mu A cm(-2)). 3. ATP (100 mu M) added apically elicited a I-sc response ( peak Delta I-sc = 6.45 +/- 0.28 mu A cm(-2)) which was similar in magn itude to that of 1 mu M thapsigargin (peak Delta I-sc = 6.09 +/- 0.44 mu A cm-2). The potency of the responses to other nucleotides: UTP gre ater than or equal to ATP > ADP much greater than AMP = adenosine indi cates the involvement of a mixture of P2Y receptors. 4. Removal of ext racellular Cl- and HCO3- reduced the I-sc response to ATP by 70% and 4 0%, respectively Removal of K+ had no effect, whereas removal of Na+ a ttenuated the I-sc response. 5. The response to ATP was insensitive to agents known to block anion secretion (except apical diphenylamine-2- carboxylate (DPC) and DIDS). The resistance to perturbation by pharmac ological agents may be a unique property of the seminiferous epitheliu m. 6. Whole-cell current recordings in cultured rat Sertoli cells demo nstrated a DIDS-sensitive outwardly rectifying Cl- conductance with ac tivating and inactivating characteristics at depolarizing and hyperpol arizing voltages, respectively. 7. The stimulation of electrogenic ion transport by ATP may be part of a complex mechanism regulating fluid secretion by the testis. Cultured Sertoli cell epithelia are shown to provide a useful model to investigate transepithelial transport in the seminiferous epithelium.