Cultured capillary endothelial cells from bovine adipose tissue: a model for insulin binding and action in microvascular endothelium.

Capillary endothelial cells were cultured from bovine adipose tissue. The endothelial nature of the cultures was documented by characteristic morphology, uniform presence of factor VIII antigen, and uptake of the endothelial cell marker Dil-Ac-LDL. The capillary cell cultures had specific, high affinity binding sites for insulin, demonstrating time and temperature dependence of binding, pH optimum, analog specificity, and inhibition of insulin binding by anti-insulin receptor antibodies. In both subconfluent and confluent cultures, insulin stimulated thymidine incorporation into DNA; significant stimulatory effects of insulin were observed at insulin concentrations of 1 ng/ml with maximal 8- to 10-fold increases at hormone concentrations of 1,000 to 10,000 ng/ml. Because of the ease of routine preparation, cell purity, presence of high affinity insulin binding sites, and insulin-sensitive metabolic responses, we suggest that the bovine capillary endothelial cultures could serve as a model cell system for the detailed study of insulin interactions with capillary endothelial cells.