Different physiological signatures of sweat gland secretory and duct cells in culture.

Human eccrine sweat gland cells grown in culture were found to lose their characteristic shape, becoming flattened and organized into multilayers. The resting membrane potentials of the cultured secretory cells (-35 +/- 2 mV, n = 36) were significantly higher than those measured for cultured duct cells (-22 +/- 1 mV, n = 58, P less than or equal to 0.01). When the cholinergic agonist methacholine (10(-5) or 10(-6) M) was administered, the cultured secretory cells could be distinguished unequivocally by their atropine-sensitive hyperpolarizing response (-20 +/- 2 mV, n = 43), whereas no cultured duct cells responded. When the sodium conductance antagonist amiloride (10(-5) or 10(-6) M) was administered, 44% of cultured secretory cells responded by hyperpolarization (-8 +/- 1 mV, n = 8), whereas 87% of cultured duct cells hyperpolarized (-15 +/- 1 mV, n = 46) and by a significantly greater margin (P less than or equal to 0.01). Substitution of chloride with gluconate in the bathing medium caused membrane potential depolarization in both cultured secretory and duct cell populations, which is consistent with the presence of a chloride conductance in the plasma membrane. The beta-adrenoceptor agonist isoproterenol induced a transient hyperpolarization of 5-10 mV in three out of six cultured secretory cells tested but had no effect on cultured duct cells.