Effects of insulin and glucose on the cells of the arterial wall: interaction of insulin with dibutyryl cyclic AMP and low density lipoprotein in arterial cells.
It has been suggested that elevated levels of insulin may be related to the development of atherosclerosis in both diabetics and non diabetics. Although insulin receptors are present on the cell membranes of both arterial endothelial and smooth muscle cells, insulin has growth-promoting and metabolic activities only on smooth muscle cells. In the present study, dibutyryl cAMP at concentration 0-1.0 mM decreased insulin binding in bovine aortic smooth muscle cells but had no effect on endothelial cells. At 2.0 mM dibutyryl cAMP had no effect on either cell type. The effect of dibutyryl cAMP was paralleled by its analogue 8-Br-cAMP and by MIX, a phosphodiesterase inhibitor. To test whether LDL receptor activity is influenced by insulin in arterial smooth muscle cells, the effect of insulin on LDL binding, uptake and degradation in bovine aortic smooth muscle cells was studied. Pre-incubation for 24 h with insulin at concentration 0-100 microU/ml resulted in a doubling of LDL binding, whereas pre-incubation for 4 h had no effect. Thus the differential effect of insulin on arterial endothelial and smooth muscle cells is similar to the effect of cAMP on insulin binding in these cells. Insulin increases binding of LDL to smooth muscle cells.
Young
I R
IR
Department of Geriatric Medicine, Queen's University of Belfast, Northern Ireland.
Stout
R W
RW
D001158:Arteries / Q000378:metabolism*; D003994:Bucladesine / Q000378:metabolism*; D002478:Cells, Cultured; D004727:Endothelium / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism; D011973:Receptors, LDL / Q000378:metabolism
D007328:Insulin; D008077:Lipoproteins, LDL; D011973:Receptors, LDL; D003994:Bucladesine; D011972:Receptor, Insulin