Effects of alcohol on blastocyst implantation site blood flow in the rat

The effect of alcohol on blood flow at sites of blastocyst implantation versus adjacent intersites was measured in conscious unrestrained rats on day 5 of pregnancy. Alcohol (0.75 ml of 100% ethanol diluted 1:2, v/v) was injected into the femoral vein (1 g/kg body wt); controls received an equivalent volume of vehicle (physiological saline). Implantation sites were rendered visible by intravenous injection of Evans Blue dye. Blood flow was measured at 15 min after alcohol injection by the 86Rb fractionation method. In controls, blood flow was significantly greater (P < 0.05) at implantation sites (0.77 +/- 0.04 ml/min/g) than at intersites (0.43 +/- 0.03 ml/min/g). Alcohol markedly increased (P < 0.05) perfusion at both sites (2.17 +/- 0.22 ml/min/g) and intersites (1.74 +/- 0.15 ml/min/g) vs respective controls. Blood alcohol levels exceeded 100 mg/dl at 10 min post-injection. Mean cardiac output and haematocrit values did not differ significantly between control and treated rats. The data indicate that alcohol enhances uterine vascular perfusion and that the vascular bed of implantation sites is susceptible to the haemodynamic effects of alcohol. Enhanced uterine blood flow may contribute to the alcohol-induced changes in embryo development, blastocyst implantation and endometrial decidualization observed in the rat.