Effect of nitrates on nutritional circulation of heart and hindlimb

Abstract

The effect of pentaerythritol tetranitrate (PETN) and nitroglycerin (NG) on the nutritional circulation in the canine hindlimb and heart was studied. Extraction of 86Rb (E) from the arterial supply to the region and clearance (C 86Rb) were used as the measure of nutritional circulation. When the rate of blood flow to the region was constant (pump perfusion) both agents produced an increase in E 86Rb and C 86Rb (C = blood flow X E) and a reduction in vascular resistance. When blood flow rate to the heart could vary (autoperfusion) the drugs reduced E 86Rb but increased C 86Rb; vascular resistance declined. Thus, under both circumstances, PETN and NG increased the nutritional circulation (C 86Rb) of the hindlimb and the heart. The autoperfusion experiments demonstrated a good correlation between blood flow and E 86Rb and C 86Rb. As blood flow was increased by the drugs, C 86Rb increased proportionately, whereas E 86Rb decreased proportionately.