Renal Mercury Content in HgCl2-Induced Acute Renal Failure in Furosemide/Saline-Protected and Nonprotected Rats

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Abstract
Renal mercury content, urinary mercury excretion and renal function were studied in rats with acute renal failure (ARF) induced by subcutaneous injection of 2, 3, 6, or 10 mg/kg HgCl2. Similarly poisoned rats were protected against ARF by continuous intravenous infusion of furosemide and saline. Excellent protection was obtained in rats receiving 2,3, and 6 mg/kg HgCl2, whilst some animals developed moderate azotemia after 10 mg/kg HgCl2. Renal mercury content 48 h after HgCl2 injection did not differ appreciably between protected and nonprotected groups of rats and showed no relation to the dose of HgCl2 injected or to the degree of renal failure. Urinary Hg excretion was variable during the first 24 h after HgCl2 injection and tended to be higher with higher dosage unless the animals became anuric early on. Hg excretion during the second 24 h was independent of dosage, but was comparatively high in functionally well protected rats and low in oliguric animals with severe renal failure. Attempts at detoxication with the potent chelating agent complexon I after 6 mg/kg HgCl2 failed completely: Renal mercury content was similar to that in the other groups of rats and every single rat so treated developed severe anuric renal failure. Although dose-dependent functional injury after HgCl2 may be related to the amount of Hg reaching the kidney during the initial phase, we have to conclude that HgCl2 toxicity is unrelated to the amount of Hg found in renal tissue at 48 h. Furthermore, furosemide/saline protection does not act through increasing urinary Hg excretion or decreasing the amount of toxin accumulating in renal tissue.