The influence of isatin on guanylyl cyclase of rat heart membranes.

Abstract The influence of indole-2,3 dione (isatin) on particulate guanylyl cyclase (GC) from rat heart membranes was investigated in the presence of adenylylimidodiphosphate (AMP-PNP). The latter activated GC in a concentration-dependent manner and 100 μM isatin abolished this effect. The IC 50 value, 2 μM, for the inhibition of stimulation of GC induced by 50 μM AMP-PNP, was close to the upper physiological level of isatin. These results indicate that isatin may interact with GC independently of its regulation by natriuretic peptides.