Enzyme activities in endothelial cells and smooth muscle cells from swine aorta.

Abstract

In populations of cultured arterial endothelial and smooth muscle cells grown under the same conditions, the total activity per cell of 10 enzymes commonly used as markers for subcellular organelles was measured: NADH:ferricyanide reductase, NADH:cytochrome c reductase (rotenone insensitive), NADPH:cytochrome c reductase, .alpha.-glucosidase, 5''-nucleotidase, alkaline phosphodiesterase I, cytochrome oxidase, monoamine oxidase, cathepsin D and N-acetyl-.beta.-glucosaminidase. Significant differences between the cell types occurred for 7 of the 10 enzymes tested. The total activity of 5''-nucleotidase in cultured smooth muscle cells was 17 times that of cultured endothelial cells. Comparison of the activities in the 2 cell types freshly collected and in culture showed that the difference in 5''-nucleotidase in cultured cells is due principally to loss of activity from endothelial cells, suggesting that this activity is regulated differently in the 2 cell types. In both cell types, cathepsin D activity rose during culture.