The acute dose-dependent effects of ethanol on canine myocardial perfusion

Acute effects of low doses of ethanol on left and right ventricular function in young healthy subjects

BACKGROUND

Moderate-to-high blood concentrations of ethanol acutely impair conventional echocardiographic measures of left ventricular (LV) performance, but the effects of low concentrations are unclear. This study explored the acute effects of low blood concentrations of ethanol on sensitive and load-independent indices of LV and right ventricular (RV) function.

METHODS

This is a crossover experimental study conducted in 64 young healthy volunteers. Participants were asked to drink a light dose of Italian red wine equivalent to 0.5 mg/kg of ethanol, and an equal volume of fruit juice in separate experiments. The following measurements were taken at baseline and 60 minutes after the challenges: tissue Doppler mitral annulus systolic velocity (S') and excursion (MAPSE), early diastolic velocity (E'), its ratio to late diastolic velocity (E'/A'), and the ratio of mitral-to-myocardial early diastolic velocities (E/E'); and tricuspid annulus systolic velocity (tricuspid S') and amplitude (TAPSE), early diastolic velocity (tricuspid E'), and its ratio to late diastolic velocity (tricuspid E'/A').

RESULTS

Blood ethanol concentration after wine intake was 0.48 ± 0.06 g/l. Compared with the control challenge, ethanol yielded a decrease in all measures of LV function (S', -9.7%; E', -11.2%; E'/A', -13.4%; MAPSE, -8.8%; p < 0.05 for all). Among indices of RV function, increases in tricuspid E'/A' ratio and TAPSE were observed (+24.5% and +9.0%, respectively; p < 0.05 for both).

CONCLUSIONS

Low blood concentrations of ethanol acutely impair LV function and increase some indices of RV function in young healthy individuals.

Ethanol-induced reduction in myocardial oxygen consumption can be attenuated by inhibiting guanylyl cyclase

We tested the hypothesis that low-dose ethanol-induced reductions in myocardial metabolism were related to increased cyclic guanosine monophosphate (GMP). Anesthetized open chest rabbits were divided into four groups: control (Ringers lactate and vehicle), ETOH (250 mg/kg i.v. ethanol and vehicle), ODQ (Ringers lactate and 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ 10(-4) M ), and ETOH-ODQ (ethanol and ODQ). ODQ, a soluble guanylyl cyclase inhibitor, or vehicle was applied topically to the epicardium for 15 min, while either Ringers lactate or ethanol was administered intravenously. Oxygen consumption (VO2 ) in both the subepicardium (EPI) and subendocardium (ENDO) was determined from coronary blood flow (radioactive microspheres) and O2 extraction (microspectrophotometry). Cyclic GMP was determined by radioimmunoassay. ETOH significantly decreased VO2 in the subepicardium (9.2 +/- 1.0-5.6 +/- 0.7 ml O2 /min/100 g) and subendocardium (9.7 +/- 0.8-7.1 +/- 0.8) and increased cyclic GMP in the subepicardium (10.2 +/- 1.7-13.8 +/- 0.8 pmol/g) and subendocardium (11.0 +/- 0.5-13.7 +/- 0.9). With ODQ, there was no significant change in the subepicardial (9.5 +/- 1.3) or subendocardial (9.0 +/- 0.9) VO2. However, ODQ caused a significant increase in both wall thickening (12.9 +/- 0.9-17.2 +/- 1.2%) and maximal rate of change in wall thickness (10.8 +/- 0.9-16.3 +/- 1.9 mm/s) and decreased subepicardium (8.3 +/- 1.3) and subendocardium (7.8 +/- 1.2) cyclic GMP. The ETOH-ODQ group had cyclic GMP (subepicardium 9.0 +/- 1.8, subendocardium 8.6 +/- 2.4) and VO2 (subepicardium 7.9 +/- 0.5, subendocardium 8.4 +/- 0.4) values similar to control. Thus, the ethanol-induced rise in cyclic GMP was associated with a decrease in myocardial O2 consumption. When this rise was blocked with a soluble guanylyl cyclase inhibitor, the reduction in metabolic demand was also eliminated. This demonstrated that the alcohol-induced reduction in myocardial metabolism was related to increased cyclic GMP and suggests a novel mechanism for the effect of ethanol.