The aim of this study was to investigate the effect of manganese chloride (MnCl₂) on liver and kidney arginase activities in rats given a high dose of gentamicin. Thirty six Wistar Albino rats were divided into 6 groups as follows: Group 1 was control group; Group 2: received gentamicin alone (gentamicin sulphate 100 mg/kg i.p.); Group 3 and 4: received MnCl₂ alone (2 mg/kg i.p. and 20 mg/kg i.p.); Group 5: received gentamicin (100 mg/kg i.p.) and MnCl₂ (2 mg/kg i.p.), Group 6: received gentamicin (100 mg/kg i.p.) and MnCl₂ (20 mg/kg i.p.). Injections were repeated daily for 6 days. Twenty four hours after the last injections samples were kidney and liver collected in rats and arginase activities were spectrophotometrically detected.

Arginase activities of liver and kidney tissues of groups receiving gentamicin (p<0.001) were higher than control group. The lower dose of MnCl₂ significantly increased liver arginase activity (p<0.001) compared to control rats, but the higher dose did not effect (p>0.05). On the other hand, both low and high doses of MnCl₂ increased kidney arginase activity (p<0.001) compared to control group. Administration of together with gentamicin and MnCl₂ increased arginase activities in both tissues. The low dose of MnCl₂ administered together with gentamicin caused more elevation (p<0.001) than high dose (p<0.001).

In conclusion, it was suggested that tissue damage in administrations of high dose gentamisin could be reduced through increased arginase activity by administration of low dose manganese.