PT  - JOURNAL ARTICLE
AU  - R J Bache
AU  - D C Homans
AU  - J S Schwartz
AU  - X Z Dai
TI  - Differences in the effects of alpha-1 adrenergic blockade with prazosin and indoramin on coronary blood flow during exercise.
DP  - 1988 Apr 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 232--237
VI  - 245
IP  - 1
4099  - http://jpet.aspetjournals.org/content/245/1/232.short
4100  - http://jpet.aspetjournals.org/content/245/1/232.full
SO  - J Pharmacol Exp Ther1988 Apr 01; 245
AB  - This study compared the effects of two selective alpha-1 adrenergic blockers, prazosin and indoramin, on the response of coronary blood flow and myocardial oxygen consumption during treadmill exercise in chronically instrumented dogs. Left circumflex coronary artery blood flow was measured with an electromagnetic flowmeter, whereas myocardial arteriovenous oxygen difference was determined with indwelling aortic and coronary sinus catheters. During control conditions, coronary blood flow, arteriovenous oxygen extraction and myocardial oxygen consumption increased regularly with exercise. Both prazosin and indoramin decreased arterial pressure at rest and during exercise, but during heavier levels of exercise blood pressure was lower and heart rates were higher after prazosin. Prazosin did not alter myocardial oxygen consumption, whereas indoramin tended to decrease oxygen consumption; myocardial oxygen consumption was significantly less after indoramin than after prazosin during the heaviest levels of exercise. Prazosin, but not indoramin, significantly decreased coronary vascular resistance both at rest and during exercise, and blunted the decrease in coronary sinus oxygen tension which occurred during exercise. In comparison with prazosin, during heavy exercise coronary blood flow was significantly decreased, myocardial oxygen extraction significantly increased and myocardial oxygen consumption significantly decreased after indoramin.