Arbutamine

Arbutamine is a synthetic catecholamine with positive chronotropic and inotropic properties. The chronotropic (increase in heart rate) and inotropic (increase in force of contraction) effects of arbutamine serve to mimic exercise by increasing cardiac work (producing stress) and provoke myocardial ischemia in patients with compromised coronary arteries. The increase in heart rate caused by arbutamine is thought to limit regional subendocardial perfusion, thereby limiting tissue oxygenation. In functional assays, arbutamine is more selective for beta-adrenergic receptors than for alpha-adrenergic receptors. The beta-agonist activity of arbutamine provides cardiac stress by increasing heart rate, cardiac contractility, and systolic blood pressure. The degree of hypotension that occurs for a given chronotropic activity is less with arbutamine than, for example, with isoproterenol because alpha receptor activity is retained.