Blood ethanol level and physiologic measurements during ethanol-induced hypertension

Plasma norepinephrine levels and alpha 2-adrenoceptor binding in central nervous system areas involved in blood pressure regulation were determined during the development of ethanol-induced hypertension in rats. Blood pressure was increased after the 4th week of ethanol feeding. Plasma norepinephrine levels of the ethanol-fed group were lower than those of the control group at most time periods studied even though blood pressure was elevated. 3H-Clonidine binding to alpha 2-adrenoceptors was decreased in the anterior and posterior hypothalamus of ethanol-fed rats throughout most of the study. Blood pressure in the ethanol-fed group was elevated when blood ethanol concentration was high, whereas blood pressure in this group was similar to that of the control group when blood ethanol concentration was low. Brain and plasma samples were taken during low blood ethanol which may explain the lack of positive findings. These results suggest that ethanol is a pressor agent and must be present to exert its cardiovascular effects. These findings suggest the importance of blood ethanol concentration at the time of study and also suggest that the blood pressure elevating effects of ethanol may be central rather than peripheral in origin.