Regulation of ion content in primary cultures from reabsorptive ducts of human sweat glands studied by X-ray microanalysis

摘要

X-ray microanalysis was used to investigate whether cAMP- and/or Ca2+-activated regulation of chloride and potassium efflux is expressed in primary cultures of sweat gland duct cells. The effects of extracellular UTP and ATP on the duct cells, and the signalling system involved in the response to ATP was also studied. Primary cultures from duct cells: of human sweat glands responded to 1 mu M carbachol, 2 mu M of the Ca2+ ionophore A23187, or 5 mM 8-bromo-cAMP stimulation for 5 min, resulting in a decrease in cellular C1 and K concentrations. 50 mu M 5-nitro-2-(3-phenylpropyl-1-amino)-benzoic acid (NPPB), a Cl- channel blocker, can inhibit the decrease in C1 concentration induced by cAMP, Extracellular (200 mu M) ATP caused a decrease of Cl and K in cultured duct cells, while (200 mu M and 2 mM) UTP was ineffective. Both the phosphoinositidase C inhibitor U73122 (10 mu M) and the absence of extracellular Ca2+ abolished the ATP-induced decrease in Cl and K content. Alloxan (1.25 mM), :an adenylate cyclase inhibitor, had an inhibitory effect on the response to ATP. The decrease in K, but not in C1, content in the cells elicited by ATP was blocked by prior incubation with 100 ng/ml pertussis toxin, indicating the coupling of ATP to pertussis toxin-sensitive G-proteins. In conclusion, both Ca2+- and cAMP-dependent Cl- permeability is present in primary cultures from duct cells of human sweat gland. The response to ATP can be mediated both by Ca2+- and by cAMP-dependent pathways, and is coupled to pertussis toxin-sensitive G-proteins. [References: 32]