An explant technique has been developed for isolating vascular endothelial cells from rat thoracic aorta. Positive identification of the cells was achieved by demonstrating a normal proliferative response to endothelial cell growth factor and by immunofluorescent staining with human Factor VIll antiserum. The formation of capillary-like structures by human umbilical endothelial cells (HUVEC) grown in culture on extracellular matrix proteins was stimulated by phorbol ester and inhibited by 8-BrcAMP. Down-regulation of the response to phorbol ester demonstrated that activation of protein kinase C is not essential for the differentiation of HUVEC into these tube-like structures. A method for obtaining freshly-isolated vascular smooth muscle cells from at tail artery has been developed. K+ -induced depolarization of these cells produced an increase in intracellular Ca 21 and Sell shorten which was reversible and could be repeated loss of effect. Epinephrine elicited a similar response, but the effects were not repeatable, indicating the presence of down-regulation.
