Uptake and efflux of calcium by canine coronary arteries and the action of adenosine

Abstract

The effect of adenosine was studied on the efflux and uptake of⁴⁵Ca by canine coronary arteries (O.D.−4 M) did not reduce the uptale of⁴⁵Ca by coronary arteries incubated in normal physiological solution and had an insignificant effect on the increased⁴⁵Ca uptake due to high [K⁺]₀. However, adenosine (10⁻⁴ M) significantly (P45Ca efflux that was induced by K⁺ depolarization (150 mM) and abolished the transient rise in efflux rate produced by aminophyllie (10⁻³ M). Aminophylline had no significant effect on the uptake of⁴⁵Ca. This study suggest that the vasodilator action of adenosine may be related to a reduction of release or an increased binding of calcium which is superficially stored. It also indicates that the antagonism between adenosine and aminophylline in the coronary blood vessels may not involve calcium influx.