A Role for Mitochondria in Myocardial Adenosine Production
It is now generally accepted that the purine nucleoside, adenosine, is a potent modulator of cardiac function. For instance, adenosine probably participates in the regulation of coronary blood flow (Berne and Rubio, 1979) and Bellardinelli et al (1982) have demonstrated that adenosine decreases the rate of sinoatrial node depolarization and the rate of conduction through the atrioventricular node. Schrader et al (1977) have shown that adenosine decreases cyclic AMP mediated increases in inotropy caused by isoproterenol treatment. Finally, it has been shown that adenosine limits norepinephrine release from sympathetic nerve endings (Verhaege, 1978). It is possible that during periods of increased oxygen demand or mild ischemia, adenosine may cause an increase in coronary blood flow to meet the increased oxygen demand. Under more severe periods of anoxia or ischemia, adenosine may have negative inotropic and chronotropic effects, reducing myocardial oxygen needs and thus having a protective effect. A similar mechanism of action for the cardioprotective effect of calcium channel blockers has recently been proposed (Cheung et al, 1984).
KeywordsCoronary Blood Flow Microsomal Fraction Mitochondrial Fraction Mitochondrial Matrix Purine Nucleoside
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