Repeated Intravenous Mercury Chloride Administration Induces Regeneration and Biphasic Renal Damage in Rats

Abstract

Mercury and its compounds are well known to be very toxic to kidneys. Forty Sprague-Dawley rats treated with intravenous injection of 0.5 mg/kg of body weight mercuric chloride (HgCl2) in 1.0 mL 0.85% NaCl through tail vein. Another group served as a control and received 1.0 mL 0.85% NaCl. The treatments were repeated every other day for ten days. Renal tissue Hg concentration of the treated group increased significantly on day 14 with a value of 2064.5 ppb/g compared to control value of 19.16 ppb/g. The renal Hg content reached 2116.89 ppb/g on day 22 and kept decreasing to its lowest value on day 38 post-treatment; 310.47 ppb/g. The necrotic cells increased significantly with time reaching peak on day 42; 6007.67 damaged cells, compared to the control count of 50.75 damaged cells. The necrosis process was accompanied by regeneration of young cells which appeared bluish in colour and could be seen as early as on day 14 with a cell count of 58 cells/10 fields. The number decreased significantly on day 22 and 26. By day 30, these young cells were no longer seen. No evidence of tissue regeneration was observed in all control samples. Repeated intravenous mercury chloride administration was observed to cause biphasic renal damage. The early damaging phase was accompanied by a high reparative epithelisation process and the severe tubular necrosis began on day 18 as soon as the reparative phase has getting waned off.