Atrial natriuretic peptide and guanylin-activated guanylate cyclase isoforms in human sweat glands

The ultracytochemical localization of membrane-bound guanylate cyclases A and C, stimulated by atrial natriuretic peptide and guanylin respectively, has been studied in human sweat glands. The results showed that the peptides stimulated guanylate cyclases A and C in both eccrine and apocrine glands. In the secretory cells, enzymatic activity was present on the plasma membranes and on intracellular membranes involved in the secretory mechanism. In eccrine glands, the cells of the excretory duct also presented enzymatic activity on the plasma membranes. In both glands, myoepithelial cells, surrounding the secretory cells, exhibited only guanylate cyclase A activity. These localizations of enzymatic activity suggest a role for both atrial natriuretic peptide and guanylin in regulating glandular secretion.