Abstract
1 The effects of papaverine on coronary blood flow, myocardial oxygen consumption, myocardial oxygen tension and the ischaemic ECG pattern were studied in anaesthetized open-chest cats representing three models of acute coronary insufficiency: ligation, spasm, and perfusion of the coronary artery at a stabilized insufficient level. 2 Despite the increase in myocardial oxygen consumption reflecting elevation of oxygen demand, papaverine improved the signs of myocardial ischaemia (the myocardial oxygen tension and ECG pattern), as long as there was a possibility of an increase in blood supply to the affected zone. Where this was exluded, the symptoms were actually aggravated. 3 The results suggest that there is no basis for dividing coronary dilators into 'benign' and 'malignant' according to their ability to increase myocardial oxygen requirements. A coronary dilator enhancing oxygen demand may prove beneficial even following complete coronary artery occlusion.