[Ca2+ inhibition of adenyl cyclase of rabbit jejunal mucosa].

Ca2+ ions at a concentration of 10-7--10-3 M inhibit adenylate cyclase of the rabbit jejunum mucosa (K0.5= =10-4 M). This effect is not modified after the membrane extraction by 10-3 M EDTA solution with a high or low ionic strength or after removal from the membrane preparation of Ca2+-dependent thermostable regulatory protein. The inhibition by Ca2+ions was discovered also in the presence of adenylate cyclase irreversible activators (guanylylimidodiphosphate and NaF), which points to the spontaneous interaction of Ca2+ ions with the catalytic subunit of the adenylate cyclase complex.