Glomerular compromise in mercuric chloride-induced nephrotoxicity.

We have examined the effects of mercuric chloride on renal glomerular structure. Isolated glomeruli from mercury-treated rats (HgCl2, 5 mg/kg body wt, s.c.) 1 hour post injection presented a diminished cross-sectional area as compared with control glomeruli [control (micron2) = 26,310 +/- 2,545, HgCl2 (micron2) = 18,474 +/- 1,828] and higher glomerular calcium content (control = 23 +/- 6 nmoles/mg prot, HgCl2 = 43 +/- 7 nmoles/mg prot). Renal sections prepared for immunohistochemical and histochemical analysis showed larger deposits of fibronectin and lipids and enhanced cellularity in glomerular structures from HgCl2-treated rats. Moreover, mieloperoxidase activity measured in isolated glomeruli were also increased as compared with control preparations [MPO (U/mg prot): control = 59 +/- 7, HgCl2 = 134 +/- 10]. When the animals were studied 24 hours post HgCl2 injection, glomerular cross-sectional area values were not different from control values (25,276 +/- 1,983 micron2), while calcium contents were higher than values observed 1 hour after treatment (92 +/- 9 nmoles/mg prot). A similar pattern was observed in fibronectin deposits. Hypercellularity in glomerular structures and the higher mieloperoxidase levels were maintained at this time (MPO HgCl2-rats 24 h = 148 +/- 31 U/mg prot). The effects observed in this study are consistent with an inflammatory response in the glomerular structure of HgCl2-treated rats that could explain the altered renal function described in previous reports in our laboratory.