Verhandelingen - Koninklijke Academie voor Geneeskunde van België
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Verh. K. Acad. Geneeskd. Belg. · Jan 1990
[Alpha-adrenergic control of coronary circulation and left ventricular function during exertion].
Sympathetic activation is responsible for a striking inotropic and chronotropic response as well as for important coronary hyperemia during exercise. However the exact role of the coronary and myocardial alpha adrenergic receptors during sympathetic activation is not well defined. It is well accepted that coronary artery smooth muscle contains both alpha-1 and alpha-2 adrenergic receptors which elicit a vasoconstrictor response upon neurogenic and humoral stimulation. ⋯ Dogs were instrumented with a solid state pressure transducer in the left ventricular cavity, a Doppler flow probe around the left circumflex coronary artery, and silastic catheters in aorta, left atrium and coronary sinus. 2-3 weeks after surgery the dogs were subjected to standard treadmill exercise. Simultaneous and continuous measurements were performed of heart rate, left ventricular systolic and end diastolic pressure, LV dP/dt/P, mean arterial pressure, late diastolic coronary vascular resistance, regional myocardial blood flow, myocardial oxygen consumption and plasma catecholamines. In the first series of experiments, coronary blood flow and myocardial oxygen consumption were analyzed in 15 conscious dogs at rest and during exercise prior to and following IV administration of phentolamine (1 mg/kg) or prazosin (0.5 mg/kg).(ABSTRACT TRUNCATED AT 400 WORDS)