[Characteristics of histamine-sensitive adenyl cyclase from cells of the gastric mucosa of the rat].

: Effects exerted by specific modifiers and ions on the adenylate cyclase activity of coarse membrane fractions of cells isolated from the rat gastric mucosa, were investigated. Fluoride ions cause 7-8-fold activation of the enzyme affecting neither the enzyme's affinity towards Mg2+-ATP, nor the cooperativeness of substrate binding. Cations Mg2+ and Mn2+ produce activating while Ca2+ inhibiting effects. GTP (10-5 M) enhances histamine activation of the enzyme and reduces maximal stimulating concentrations of histamine. GTP and Gpp(NH)p exert activating action on the enzyme causing 2- and 5-fold activation, resp. Adenosine suppresses the enzyme activity, the effect being potentiated by GTP. The plausible role of N-protein in the regulation of the enzyme activity is discussed.