Halothane Relaxes Previously Constricted Isolated Porcine Coronary Artery Segments More Than Isoflurane

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Abstract
Coronary vasodilation by halothane and isoflurane were compared using in vitro tesion recording. Porcine left anterior descending coronary arterial segments (1.5-2.0 mm o.d.) were constricted with either K + (30 mM) or prostanoid U44069 (6 .times. 10-7 M) in the absence of other drugs or anesthetics. Following stabilization of constriction, arteries were exposed to halothane or isoflurane at 0.5, 1.0, 1.5, 2.0, ad 3.0% concentrations. K+ (30 mM) induced constriction was reduced by halothane at 1.5, 2.0, and 3.0% and U44069 (6 .times. 10-7 M) induced constriction was reduced at 0.5, 1.0, 1.5, 2.0, and 3.0%. K+ (30 mM) induced constriction was reduced by isoflurane only at 3.0% and U44069 (6 .times. 10-7 M) induced constriction was reduced by isoflurane only at 2.0 and 3.0%. U44069 induced constriction was more susceptible than K+ induced constriction to relaxation by halothane or isoflurane. Halothane was more potent than isoflurane as a direct relaxant of porcine epicardial left anterior descending arterial segments previously constricted with K+ (30 mM) or U44069 (6 .times. 10-7 M).