title: Nicotine increases heart adenosine release, oxygen consumption, and contractility.
abstract: The effect of nicotine on adenosine release, oxygen consumption, and contractility was investigated in perfused rat hearts. Continuous infusion of nicotine into the perfusing physiological saline (PS) elicited a propranolol (10(-6) M) sensitive transient elevation of developed left ventricular pressure (LVP) and maximum rates of left ventricular pressure development and relaxation (+/- dP/dtmax) within 20 s, which subsequently declined to maintained elevated plateau levels by 1 min. The continuous infusions of nicotine to achieve PS concentrations of 5 X 10(-4), 1 X 10(-4), or 5 X 10(-5) M, respectively resulted in significant increases in the mean plateau levels of LVP (33.4, 10.1, or 6.3%), +dP/dtmax (26.3, 10.8, or 6.9%) and-dP/dtmax (35.0, 11.9, or 9.0%) at 1 min. The inclusion of propranolol (10(-6) M) with or without atropine (10(-6) M) did not alter these maintained plateau responses to nicotine. During the plateau phase of the contractile response oxygen consumption of the hearts was significantly elevated by 36, 19, or 11%, and mean levels for adenosine in the coronary effluent rose by 261, 76, or 74% in response to 5 X 10(-4), 1 X 10(-4), or 5 X 10(-5) M nicotine, respectively. Nicotine did not influence [14C]adenosine uptake by the hearts. These results suggest that nicotine is capable of 1) augmenting cardiac contractility and oxygen consumption independent of beta-adrenergic or muscarinic influence, and 2) elevating the appearance of adenosine in the coronary circulation presumably by enhancing myocardial production of the nucleoside.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D009538:Nicotine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects*; D010477:Perfusion; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D016276:Ventricular Function
chemical_list: D009538:Nicotine; D001285:Atropine; D011433:Propranolol; D000241:Adenosine; D000109:Acetylcholine