Effects of gentamicin sulfate on enzyme activities of carbonic anhydrase from human erythrocytes in vitro and from rat erythrocytes in vivo.

The effects of gentamicin sulfate on carbonic anhydrase (CA) enzyme activity in in vitro human and in in vivo rat erythrocytes were investigated. For in vitro study, human carbonic anhydrase-I and -II (HCA-I and HCA-II) were purified by affinity-column chromatography, and rats were used for in vivo study. In vivo and in vitro CA enzyme activity was determined colorimetrically using the CO2-hydration method of Wilbur and Anderson as modified by Rickli et al. Gentamicin sulfate (1.98-9.90 mM) showed in vitro inhibitory effects on HCA-I and HCA-II hydratase activity up to a 2 mM concentration, when determined using the C02-hydratase method. Rat erythrocyte CA activity was significantly inhibited for up to 3 h (p<0.001) following intramuscular administration of gentamicin sulfate to Sprague-Dawley rats (3.2 mg/kg body weight). In conclusion, gentamicin sulfate inhibits CA enzyme activity in vivo and at low concentrations in vitro, but activated it at high concentrations (> or = 4 mM) in vitro.