Activation of guanylate cyclase and the regulatory role of cyclic 3',5'-guanosine monophosphate

The effect of dithiothreitol on the activity of soluble guanylate cyclase and on enzyme activation by sodium nitroprusside and free stable radical was studied. A higher degree of oxidation of guanylate cyclase from rat platelets in comparison with that of the enzyme from human platelets was found, which influences both the value of the enzyme activity and its regulation. It was shown that dithiothreitol enhanced the stimulating effect of nitroprusside but inhibited the activation of guanylate cyclase by free radical, which was suggestive of a difference in the mechanisms of the activating effect of these agents. A scheme of the biological role of cyclic 3',5'-guanosine monophosphate was proposed. On the basis of this scheme, different pathological states caused by disturbances in the functions of guanylate cyclase were identified and investigated.