Arterial Procollagen Type I, Type III, and Fibronectin: Effects of Diabetic Serum, Glucose, Insulin, Ketone, and Growth Hormone Studied on Rabbit Aortic Myomedial Cell Cultures

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Abstract
Arterial myomedial cell cultures were grown from thoracic aortas of normal rabbits. The effect of normolipemic serum from young nonobese male juvenile diabetics on the production of procollagen type I, type III, and fibronectin was studied on nearly confluent primary cultures not treated with trypsin and incubated in the presence of [U-14C]-proline. The macromolecules were isolated from the incubation medium by ammonium sulfate precipitation, fractioned by DEAEcellulose chromatography and SDS urea-polyacrylamide gel electrophoresis, and quantitated by liquid scintillation counting. Media containing diabetic serum enhanced the production of procollagen type I (P < 0.05). There was no effect on the elaboration of procollagen type III. Diabetic serum, however, stimulated the production of fibronectin (P < 0.005). There was no relationship between the glucose level and the amount of either procollagen type I or fibronectin. Growth medium supplemented with normal serum and extra glucose did not change the production of procollagen type III or fibronectin but decreased the elaboration of procollagen type I (P < 0.05). Addition of insulin (100 μU/ml) resulted in a significant decrease in procollagen type I, type III, and fibronectin elaboration (P < 0.05, P < 0.02). When ketones (0.2 mM) were added together with normal serum, no changes in the procollagens and fibronectin were observed. Supplementation of normal serum with human growth hormone (1 ng/ml) resulted in a significant increase in the production of procollagen type I (P < 0.02) and fibronectin (P < 0.01). The present results demonstrate that the factor(s) in normolipemic diabetic human serum enhancing theproduction of procollagen type I and fibronectin by arterial myomedial cell cultures cannot be imputed to glucose, insulin, or ketones, but leaves growth hormone as one possible factor The data may be relevant for the understanding of the development of human diabetic macroangiopathy.

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