Jan 1, 1985

Two distinct effects of oxygen on vascular tone in isolated porcine coronary arteries

Circulation Research
G M Rubanyi, R J Paul


The relation between PO2 and vessel tone was studied in isolated porcine left descending coronary artery rings. Porcine left descending coronary artery mounted isometrically and equilibrated in Krebs-bicarbonate solution (37 degrees C, pH 7.4, when gassed with 95% oxygen + 5% carbon dioxide) exhibited spontaneous basal tone. Decreasing bath PO2 to 40%, 20%, and 12% elicited sustained increases in basal tension which were reversible, ranging between 10% and 20% of the contraction induced by 40 mM potassium chloride. Further decreases in PO2 to near zero (anoxia) resulted in relaxation to baseline. Cyclooxygenase inhibitors indomethacin (5.5 X 10(-6) M), aspirin (5 X 10(-5) M), and meclofenamate (10(-5) M) decreased vascular tone and totally prevented coronary vasoconstriction induced by lowering bath PO2 to 12% or 40% but did not affect anoxic vasorelaxation. Neither basal tone nor the vasoconstriction induced by decreases in bath PO2 were influenced by the antihistaminergic drug pyribenzamine (10(5) M) or by the alpha-adrenergic blocker phentolamine (10(-6]. Isoproterenol (10(-9) to 10(-8) M) or an elevation of the bath potassium concentration from 5.9 to 11 mM significantly augmented coronary vasoconstriction induced by loweri...Continue Reading

Mentioned in this Paper

Muscle, Smooth, Vascular
Sinus Node Artery
Beta-adrenergic receptor

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