Hyperlipidaemia and the progression of nephropathy in OLETF rats: effect of angiotensin-converting enzyme inhibitor, enalapril.

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1. The influence of angiotensin-converting enzyme (ACE) inhibitor is investigated in enalapril on renal function in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of spontaneously non-insulin-dependent diabetes (NIDDM). 2. Enalapril (5 mg/kg) or vehicle was administered once daily by gastric gavage to 22-week-old male OLETF rats for 32 weeks. Blood pressure, albuminuria, creatinine clearance, plasma glucose, serum insulin and lipids were determined before and during the treatment. Renal haemodynamics was examined at the end of the treatment. 3. Enalapril lowered blood pressure mildly but significantly. In the vehicle-treated rats, urinary albumin excretion increased from 0.75 +/- 0.16 mg/mg creatinine (Cr) to 8.65 +/- 0.78 mg/mg Cr. Enalapril significantly blunted the development of albuminuria from 0.66 +/- 0.12 mg/mg Cr to 5.19 +/- 0.67 mg/mg Cr (P < 0.008) without significant influence on creatinine clearances. Enalapril also significantly blunted the rise in serum cholesterol and triglyceride prior to the development of massive albuminuria. Enalapril did not affect bodyweight, plasma glucose or insulin levels. Renal haemodynamics assessed by inulin and p-aminohippuric acid clearances were similar in both groups at the end of the treatment. 4. These results reconfirmed that the ACE inhibitor has protective effects on nephropathy in NIDDM. Massive albuminuria was preceded by increase in serum lipids in OLETF rats, which supports the view that hyperlipidaemia exacerbates glomerular injury in chronic renal disease. Enalapril attenuated the rise in serum lipids, suggesting that the beneficial effects of the compound on renal injury in OLETF rats might also be mediated through the action of affecting serum lipids.