Feb 1, 1972

Differences in direct effects of adrenergic stimuli on coronary, cutaneous, and muscular vessels

The Journal of Clinical Investigation
A L MarkH E Mayer

Abstract

Direct effects of adrenergic stimuli on coronary vessels in dogs were compared with effects on vessels to skin (hind paw) and skeletal muscle (gracilis muscle) after intravenous administration of practolol (2 mg/kg), a selective myocardial beta receptor blocker which minimized indirect effects of myocardial stimulation on coronary vascular resistance. The left circumflex coronary, cranial tibial, and gracilis arteries were perfused separately but simultaneously at constant flow. Perfusion pressures, left ventricular pressure and dP/dt. and heart rate were recorded. Changes in perfusion pressure to each bed reflected changes in vascular resistance. The direct constrictor effects of sympathetic nerve stimulation, norepinephrine and phenylephrine on coronary vessels were minimal compared with effects on cutaneous and muscular vessels. Subsequent blockade of vascular beta receptors did not augment the constrictor responses. Angiotensin, a nonadrenergic stimulus, produced striking coronary vasoconstriction which exceeded that in skin and approximated that in muscle. These results suggests that there is a paucity of alpha adrenergic receptors in coronary vessels compared to cutaneous and muscular vessels. Direct dilator responses to ...Continue Reading

Mentioned in this Paper

Arterial System
Practolol
Sympathetic Nervous System
Vascular Resistance
Pathologic Vasoconstriction
Blood Vessel
Sympathetic Nerve Structure
Entire Gracilis Muscle
Pathological Dilatation
Coronary Vessels

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