DIRECT EFFECTS OF PROPOFOL (2,6-DIISOPROPYLPHENOL) ON CANINE CORONARY-ARTERY RING TENSION

1. The direct effect of the intravenous general anesthetic propofol (2,6-diisopropylphenol) on epicardial coronary artery tone was studied in unstimulated canine coronary artery rings. 2. Rings stretched to a basal tension of 5 g and exposed to increasing concentrations of propofol generated a characteristic dose-dependent biphasic change in tension-concentrations from 10(-7) to 10(-5) M resulted in constriction (+477 +/- 118 mg) while concentrations 10(-4) and 10(-3) M resulted in relaxation (- 682 +/- 75 mg). 3. The response to propofol was reversible and was not modified by the presence of endothelium, alpha1 and beta adrenoceptor blockade or TEA sensitive potassium channel blockade. 4. The propofol induced changes in tension were altered by changes in extracellular calcium concentrations as well as by blockade of the voltage dependent calcium channel by verapamil. 5. These experiments suggest that clinical concentrations (human) of propofol may have direct vasoactive effects on epicardial coronary artery smooth muscle and that these effects may be due to actions on voltage dependent calcium channels of vascular smooth muscle.