Acute Effects of Nicotine on Glycolysis of Rat Myocardium with Special Reference to Cardiovascular Effects

Acute effects of nicotine bitartrate (Nic.) on glycolysis intermediates concentrations in the heart of female rat were studied with special reference to cardiovascular effects. Biphasic (fast negative and slow positive) inotropic and chronotropic effects of Nic. (100μM) on spontaneous beating atrial preparations were observed. The negative inotropic and chronotropic effects were inhibited by atropine (15nM) and positive inotropic effect was inhibited by propranolol (150nM) significantly, suggesting that fast negative effects were mediated through muscarinic cholinergic receptors and slow positive inotropic effect was through β-adrenergic receptors. Positive chronotropic effect was not inhibited significantly by 150nM propranolol. At the plateau phases of positive response by nicotine with or without atropine, glycolysis intermediates in the atrial preparation was measured and no significant change was observed. Blood pressure decreased by 5-min-infusion of Nic. (20μg) under pentobarbital anesthesia, which disagreed with the reports using dog and cat. At 5 and 20 min after the start of Nic. infusion, no significant change on glycolysis intermediates concentrations was observed in myocardium. These results suggested that the effects of nicotine on glycolysis in myocardium did not appear significantly by acute treatment.