Chronic lead exposure in rats: effects on blood pressure.

The influence of Pb exposure on blood pressure was investigated in Wistar Kyoto, Sprague Dawley and stroke prone spontaneously hypertensive rats. In short-term experiments, a dose-dependent decrease of blood pressure was found with administration of Pb acetate in drinking fluid. This effect was more pronounced in young, male as compared to old, female animals. Pressor responses to noradrenaline and ANG II were decreased. In contrast, long-term Pb exposure of more than 1 year duration consistently caused hypertension. In SHR-sp a high proportion of animals died from cerebrovascular haemorrhage even before developing hypertension. Chronically Pb exposed hypertensive rats had increased plasma volume and total body sodium despite normal renal function. Plasma concentrations of catecholamines and PRA were normal. The results show a biphasic effect of Pb on blood pressure. An important role of renal sodium retention in chronic Pb-induced experimental hypertension is suggested.