Adenosine constricts the isolated and perfused monkey coronary artery

Abstract

Adenosine constricted 37 of 58 isolated and perfused monkey coronary arteries, whereas it dilated dog coronary arteries in all cases. The vasoconstriction induced by 0.1-10 micrograms (0.37-37.4 nmol) of adenosine was examined, since adenosine in large doses produced tachyphylaxis. The adenosine-induced vasoconstriction was significantly attenuated by diltiazem (100 micrograms [0.24 mumol]), although it was not affected by aminophylline (100 micrograms [0.23 mumol]), phentolamine (100 micrograms [0.36 mumol]), or methysergide (10 micrograms [28 nmol]. Forty-minute treatment with indomethacin (5 x 10(-6) mol/l) completely prevented the adenosine-induced vasoconstriction, but it did not significantly inhibit vasoconstriction induced by KCl (3 mg [40 mumol])- or norepinephrine (NE, 0.1 micrograms [0.59 nmol]). These results suggest that: (1) adenosine constricts monkey coronary arteries by increasing Ca2+ influx across the smooth muscle cell membrane; (2) cyclooxygenase products may be involved in the adenosine-induced vasoconstriction; (3) adenosine receptors may not be involved in the vasoconstriction.