EFFECT OF CHRONIC EXPOSURE TO LOW LEVELS OF LEAD ON RENAL FUNCTION AND RENAL ULTRASTRUCTURE IN SD RATS

Chronic exposure to lead is associated with adverse effects on renal function in laboratory animals and man. There is controversy concerning the direction of change of renal function parameters following chronic lead intoxication. The renal effects of low-dose lead exposure, as opposed to acute and pharmacological doses, require further scrutiny. In order to determine the effect of prolonged low-dose lead exposure, male Sprague Dawley rats (initial weight, 150.5±17.4g; final weight, 300.5 ± 17.4g; n=10) administered lead acetate (100 p.p.m.) in drinking water over a period of 3 months, were investigated for renal function parameters. Treated rats had elevated blood pressures (114.4±4.2 vs. 95.7±3.5 mmHg; P<0.01). There was no significant difference in renal blood flow (3.99±0.28 vs. 4.19±0.63 ml/min; P=NS). GFR was comparable in the two groups (0.77±0.05 vs. 0.88±0.06 ml/min; P=NS). No significant difference in serum creatinine was observed (57.8±7.5 vs. 49.0±2.7 mmol/l; P=NS). Renal histology showed minimal interstitial changes in the experimental group. Interestingly, significant sodium (P<0.01); potassium (P<0.05) and chloride (P<0.05) retention were observed in the lead treated rats. Elevation of blood pressure occurred at a stage when low-level lead exposure did not alter renal function parameters appreciably. These results suggest that hypertension may be a forerunner of significant renal damage following chronic exposure to low-levels of lead and further underscore fluid and electrolyte retention as a significant mechanism responsible for elevated blood pressure in the chronic stages of lead exposure.