The combined cardiovascular effect of alcohol and noise in rats.

Groups of 20 CFY male rats were made to drink water containing 10% alcohol and 5% sugar or 5% sugar. Half of both groups (10-10 animals) were exposed to 95 dBAeq mixed industrial noise for 3 weeks, 6 hours daily. Haemodynamic measurements were carried out using isotope (57Co) labelled microspheres, which were repeated after the i.v. administration of 30 micrograms/kg/3 min noradrenaline, using a second isotope (113Sn). It was found, that alcohol decreased the cardiac fraction of the cardiac output, the nutritive blood flow of the myocardium and increased the vascular resistance of the adrenals. Noise decreased the lung fraction of the cardiac output and the hepatic blood flow. Interaction between noise and alcohol, inhibiting the effect of alcohol, was demonstrated on the intestinal blood flow, adrenal fraction of cardiac output and testicular vascular resistance. The haemodynamic effects of noradrenaline observed in the control were in several organs more or less modified in the animals treated with alcohol or noise or both. It was concluded that the exposures (alcohol, noise or both) modify the alpha-adrenergic effect of noradrenaline.