Effect of chronic renal failure and methylprednisolone treatment on the uptake of labelled plasma cholesterol into the aorta of normocholesterolemic rabbits

Abstract

The effects of chronic renal failure (CRF) and corticosteroid treatment on the aortic uptake of labelled free and esterified cholesterol (FC and EC) were investigated in normocholesterolemic rabbits. Methylprednisolone, 0.4 mg/day, or placebo was administered for 14 weeks to rabbits with normal renal function and with CRF. Then [ 3H]- and [ 14C]cholesterol were administered intravenously and orally, respectively. The radioactivity levels of FC and EC in plasma were measured at regular intervals. After 48 h the accumulation of 3H and 14C radioactivity of FC and EC in the intima-media of the thoracic aorta was determined. An aortic uptake' coefficient was calculated by dividing the tissue radioactivity (dpm/cm 2/h) by the mean plasma radioactivity (dpm/ml). The mean uptake coefficient of EC in normal rabbits was 6 nl/cm 2/h, the value for FC being 180 nl/cm 2/h. In normal rabbits treated with methylprednisolone the uptake coefficients of both FC and EC were significantly decreased to about 50% of the values in normal rabbits receiving placebo. A similar significant decrease in the uptake coefficients was found in the CRF rabbits receiving placebo. No further decrease was observed in the CRF rabbits treated with methylprednisolone. The cholesterol content of the aortic intima-media was significantly decreased only in CRF rabbits on methylprednisolone treatment. The results do not indicate an acceleration of uremic arterial disease by steroid treatment in the rabbit.