Metabolic changes in modified smooth muscle cells of rabbit carotid arteries

In the common carotid artery of rabbits, intimal myocyte proliferations were induced by daily repeated local electrical stimulation of the vessel wall in combination with a cholesterol containing diet given for 4 weeks. Some biochemical parameters of the morphologically modified intimal smooth muscle cells were studied and compared with those of samples obtained from nonstimulated tunica media of the contralateral carotid artery. The results show that in relation to dry weight both alkali extractable protein and DNA content of the proliferates are increased to about 125%. In the proliferates, the in-vivo tissue concentrations of glucose and glycogen are only 50-70% of the normal values, whereas the concentration of lactate is increased to about 160%. In-vitro incubation experiments of excised tissues samples from the intimal proliferates and normal media indicate that under an optimal supply of substrates the glucose uptake and lactate production of the proliferates are increased to 140% and 150%, respectively. This results provides evidence for an increased capacity of glycolysis in the proliferates, which in vivo may lead to a decrease in glucose concentration and to an increased concentration of lactate. This investigation shows that modified smooth muscle cells proliferating in the arterial intima exhibit an activated metabolism as seen in other models of arteriosclerosis.