[Cardiac guanylate cyclase in rats with ischemic damage to the myocardium]

The activity of soluble guanylate cyclase (GC) of rat heart and the regulatory activity of dithiothreitol (DTT) and sodium nitroprusside under ischemic myocardium damage caused by ligation of left coronary artery has been investigated. After coronary occlusion the GC activity in the presence of Mn2+ or Mg2+ decreases both in ischemic and in intact zones (40% from normal) in 15 min, in 24 h it more diminishes (up to 30%) in the ischemic zone, in intact zone it partially normalizes (up to 70%). The stimulatory effect of DTT on the GC activity in studied heart zones doesn't differ from control. The activation of GC by nitroprusside in ischemic zone decreases in 15 min, it is practically absent in 24 h. The decrease of GC activation in intact zone is less expressed. It is suggested that the reduction of GC activation by sodium nitroprusside is due to the loss of the heme by the enzyme during ischemia.