Experimental model of lead nephropathy. IV. Correlation between renal functional changes and hematological indices of lead toxicity.

Adverse effects on hematopoiesis and renal function have been reported in both animals and humans exposed to high doses of lead for a protracted period of time, but little is known about the interrelationship between these two target organ systems. The present study examines rats exposed via drinking water to high dose (5000 mg/L) or low dose (100 mg/L) lead, either continuously or discontinuously, for periods ranging from 1 to 12 months. In addition to blood lead, indices of hematological abnormalities included hematocrit, zinc protoporphyrin (ZPP) and red blood cell (RBC) membrane sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase). Renal function abnormalities were assessed by measurements of glomerular filtration rate (GFR) by the single injection 125-I-iothalamate technique and urinary excretion of the proximal renal tubular enzyme, ligandin. Blood lead and GFR correlated positively during the first 6 months of lead administration, reflecting a stimulatory effect of lead on renal hypertrophy and GFR during this time period. When this distorting effect was factored out, there were few residual correlations between renal and hematological abnormalities. The only significant relationship between GFR and hematological parameters of lead toxicity was a negative correlation between GFR and RBC membrane Na-K-ATPase in animals treated with high dose lead for 6 months and observed at the end of 12 months (discontinuous group).(ABSTRACT TRUNCATED AT 250 WORDS)