Cardiac contractile and sarcoplasmic reticulum function after acute ethanol consumption.
Since the contractile status of the myocardium depends on tight regulation of calcium concentrations by the sarcoplasmic reticulum (SR), we investigated the possibility that acute ethanol-induced alterations in the calcium pump function of the SR could contribute to the myocardial depression seen after acute ethanol exposure. In this study, LV function (Langendorff preparation) was significantly reduced after ethanol (ETOH, 2.0 ml/kg, iv) in adult guinea pigs. Compared to control hearts (N = 10), hearts from ethanol-treated animals (N = 10) had significantly lower peak systolic LVP (84 +/- 2 vs 67 +/- 4 mmHg, P < 0.005), +dP/dt max (1175 +/- 54 vs 967 +/- 54 mmHg/sec, P < 0.02), and -dP/dt max (1087 +/- 42 vs 892 +/-52 mmHg/sec, P < 0.02) and at a maximal isoproterenol dose of 30 ng/ml, had lower LVP (150 +/- 5 vs 90 +/- 6 mmHg, P < 0.02), +dP/dt max (3400 +/- 120 vs 180 +/- 40 mmHg/sec, P = 0.001), and - dP/dtmax (2500 +/- 50 vs 1520 +/- 40 mmHg/sec, P < 0.002) than control hearts. SR calcium ATPase activity was not altered by ethanol (control: 70.6 +/- 2.6 micromol/mg protein/hr, N = 10; ETOH: 81.3 +/- 6.9, N = 8). Maximal calcium uptake, however, was decreased by 25% in SR vesicles isolated from ethanol-treated (3.8 +/- 0.27 micromol/mg, N = 10) compared to control hearts (5.1 +/- 0.20, N = 10, P < 0.01). Our data confirm that moderate doses of ethanol depress cardiac contractile function, and our finding that acute ethanol exposure decreased calcium uptake by the SR in the face of no change in calcium ATPase activity suggests that ethanol uncoupled ATP hydrolysis and calcium transport.
Horton
J W
JW
Department of Surgery, University of Texas Southwestern Medical Center, Dallas, 75235-9031, USA.
White
D J
DJ
D000136:Acid-Base Equilibrium / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D009206:Myocardium / Q000166:cytology*; D012519:Sarcoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism
D000431:Ethanol; D002118:Calcium