Decreased mitogenic activity in hypercholesterolaemic plasma.

Abstract

The mitogenic activity on rat aortic smooth muscle cells of plasma from patients with hypercholesterolaemia was compared to that of plasma from a normocholesterolaemic control group and to that obtained after lowering plasma cholesterol levels in the hypercholesterolaemic groups with simvastatin. Mean plasma total and low density lipoprotein cholesterol and apolipoprotein B concentrations in the two groups were 8.62 +/- 0.62 mmol l-1, 7.03 +/- 0.56 mmol l-1 and 1.96 +/- 0.14 g l-1, respectively, and 5.05 +/- 0.20 mmol l-1, 3.42 +/- 0.18 mmol l-1 and 0.80 +/- 0.04 g l-1, respectively, all differences significant at P less than 0.001. During simvastatin treatment these parameters decreased to 5.70 +/- 0.35, 4.15 +/- 0.33 mmol l-1 and 1.33 +/- 0.08 g l-1, all changes being significantly (P less than 0.001) lower than before treatment. Hyperlipidaemic plasma in untreated patients had a significantly lower mitogenic activity than normolipidaemic control plasma as measured by autoradiographic labelling of DNA after 3H-thymidine incorporation, 25.7 +/- 1.8% vs. 32.0 +/- 1.9%, P less than 0.05. Lowering plasma cholesterol levels in the hyperlipidaemic patients 'normalized' the mitogenic activity to 32.3 +/- 1.6%, P less than 0.05. The reason for this unexpected finding is not known.