Electrophysiological responses to oxytocin and ATP in monolayers of a human sweat gland cell line

It was shown that oxytocin (OT) elicits electrophysiological responses in cultured monolayers of NCL-SG3, a human immortalized sweat gland cell line. The response to OT was greater for basal applications. It was also found that monolayers respond to ATP with a transient transepithelial-potential change, with a more pronounced response to apical than to basal applications. The IC50 for the response to OT was 180 nM at room temperature. The response to OT was not due to effects of OT on vasopressin (AVP) receptors as evidenced by three tests: (a) The response was completely blocked by the selective OT-receptor antagonist [Mpa(1),D-Tyr(Et)(2),Thr(4),Orn(8)]-OT (CAP) applied at equal concentrations (100 - 1000 nM) to that of OT. (b) The response to OT was similar to that of ionomycin (2 mu M) or ATP (150 mu M). In contrast, the response to AVP (500 nM) or cAMP (2 mM) were smaller and of a different time course. (c) OT increased but AVP had no effect on the intracellular free calcium. It is suggested that OT may have a role in the regulation of salt balance in sweating. (C) 1997 Academic Press.