Enhancement on expression of LDL receptors in cultured rhesus renal epithelial cells by verapamil

In order to investigate the anti-atherogenic properties of calcium antagonists, human serum low density lipoproteins (LDL) were isolated by density gradient ultracentrifugation and iodinated with 125I by iodine monochloride method. Effects of verapamil on activity of LDL receptors in cultured rhesus renal epithelial cells were examined by radioligand analysis. The receptor-mediated binding, internalization, and degradation of cultured cells pretreated with verapamil 44 mmol.L-1 for 24 h and cells pretreated for 24 h and incubated for 10 h with verapamil were increased compared with control group (61 +/- 11, 52 +/- 8 vs 20 +/- 3.5, 1006 +/- 106, 579 +/- 124 vs 253 +/- 78, 630 +/- 43, 541 +/- 46 vs 374 +/- 53 125I-LDL/micrograms.g-1 cell protein). In verapamil-treated cells without verapamil pretreatment, increased internalization and degradation were not significant, and binding was not increased. When the cells were pretreated with verapamil 22 mmol.L-1 for 24 h and then incubated with 5, 20, 50 125I-LDL/mg.L-1, binding and internalization were increased, increased degradation was seen only with 50 125I-LDL/mg.L-1. The results indicated that the verapamil enhances expression of LDL receptor in cultured rhesus renal epithelial cells, which might contribute to the protective effects of calcium antagonists in experimental and human atherosclerosis