Paradoxical effects of isoproterenol, nitroglycerin and exercise in conscious dogs with myocardial ischemia

S. F. Vatner, R. J. McRitchie, P. R. Maroko

Research output: Contribution to journalArticlepeer-review


It is known that isoproterenol, other cardioactive catecholamines and exercise improve ventricular function in the normal heart. Isoproterenol and exercise improve function primarily through beta adrenergic stimulation resulting in an augmentation of myocardial contractility, while nitroglycerin improves function slightly by a combination of decreased afterload associated with systemic vasodilatation and increased reflex sympathetic drive. It has been presumed that isoproterenol and nitroglycerin act favorably in the ischemic heart and are frequently administered to patients with severe coronary artery disease and myocardial ischemia. On the other hand, it is recognized clinically that these drugs, as well as exercise, in patients with myocardial pump failure can result in deterioration of cardiovascular performance. As has been demonstrated by Gorlin and associates and Gunnar et al., isoproterenol does not necessarily improve ventricular function in patients with severe coronary artery disease and can result in excess lactate production. Recently the authors observed that this agent produces extension of myocardial injury secondary to acute coronary artery occlusion. The present investigation was directed towards comparing the responses to these interventions in the normal heart and also in the presence of either global or regional myocardial eschemia in conscious dogs instrumented for radio telemetry of direct and continuous measurements of left ventricular dimensions and pressure and coronary blood flow.

Original languageEnglish (US)
Pages (from-to)201-213
Number of pages13
JournalTransactions of the Association of American Physicians
VolumeNo. 86
StatePublished - 1973
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Medicine(all)


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