Susceptibility of ageing kidney to quinidine.

Male Fischer-344 rats aged 3-4 months and 30-32 months were used in this study. Quinidine in vitro reduced accumulation of organic ions, p-ammonium hippurate (PAH) and tetraethyl ammonium (TEA), inhibited oxygen consumption and increased LDH leakage, in renal cortical slices. High concentrations of quinidine (2 and 3 mmol l-1) produced overt toxicity and no age related differences in any of the parameters measured were observed. But at lower concentrations significant age-related differences in kidney susceptibility to quinidine were evident. Administration of 75 mg kg-1 day-1 quinidine for 4 days caused exacerbated renal damage in senescent rats compared to young adults as demonstrated by greater elevation of blood urea nitrogen and serum creatinine, and greater inhibition of TEA uptake in renal cortical slices. These results establish significant age related differences in renal damage due to quinidine.