Combination therapy with paricalcitol and enalapril ameliorates cardiac oxidative injury in uremic rats.

AIMS

This study investigated the protective effect of the angiotensin-converting enzyme inhibitor, enalapril, and the vitamin D analog, paricalcitol, alone or in combination, on cardiac oxidative stress in uremic rats.

METHODS

Rats were made uremic by 5/6 nephrectomy and treated for 4 months as follows: (1) uremic + vehicle (n = 11); (2) uremic + enalapril (30 mg/l in drinking water, n = 13); (3) uremic + paricalcitol (200 ng 3x week, n = 6); (4) uremic + enalapril + paricalcitol (n = 14), and (5) controls (n = 6).

RESULTS

Cardiac NADPH oxidase activity increased by 300% in uremic rats compared to normal controls. Treatment with enalapril, paricalcitol or the combination of the two protected uremic rats from cardiac oxidative stress by inhibiting enzyme activity. Cardiac malondialdehyde (MDA) levels were significantly increased in uremic rats compared to normal controls. Only the combination therapy inhibited the increase in MDA levels in uremic rats. Cardiac glutathione was significantly reduced in uremic rats compared to normal controls. Enalapril, paricalcitol or the two in combination all protected against this reduction in glutathione. Cardiac copper/zinc superoxide dismutase (CuZn-SOD) activity decreased whereas manganese (Mn-SOD) activity increased in uremic rats compared to controls. Both mono and combination therapies ameliorated the alterations in cardiac SOD activity seen in uremic rats.

CONCLUSION

Enalapril, paricalcitol and their combined therapy afford protection against cardiac oxidative stress in uremia.