Effect of Nicotine on the Coronary Blood Flow and Related Circulatory Parameters

Abstract

The effect of intravenously administered nicotine (20 µg ./Kg./min.) on the coronary blood flow and related hemodynamic parameters was studied in the normal intact dog and in the dog with chronic coronary insufficiency as produced either by coronary artery ligation or gradual coronary artery narrowing. Nicotine increases cardiac work markedly by an increase in the mean arterial blood pressure and cardiac output. The degree of this increase is similar in normal dogs arid dogs with chronic coronary insufficiency. The mean control coronary blood flow was moderately decreased in dogs with coronary artery ligation and markedly decreased in dogs with narrowing of the two main branches of the left coronaryatery. Nicotine produced an increase in coronary blood flow which in normal dogs was observed to be as high as 125 per cent on an average over the control value. The average increase was consider ably less in dogs with ligation of one coronary artery branch (82.5 per cent) and in dogs with narrowing of two main branches (83.3 per cent). The degree of coronary narrowing and/or occlusion was directly related to the response of the coronary flow; the greater the coronary impairment, the smaller was the increment in corollary blood flow frequently dropped below the control value in the postinfusion period, Coronary vascular resistance and myocardial oxygen utilization declined during the event of nicotine administration. The response of the coronary blood flow to nicotine resembled that of anoxemia in the presence of coronary insufficiency. These findings would appear to have a bearing on the clinical problem relative to the effect of nicotine in the human subject with coronary artery disease.