Lysosomes in aortic smooth muscle cells. Effects of hypertension.

Hypertension induces hypertrophy and increased turnover of aortic smooth muscle cells along with an accumulation of connective tissue in the aortic wall. We identified the lysosomes in normal and hypertensive aortic muscle cells by light and electron microscopy, utilizing cytochemical staining for acid phosphatase activity. Lysosomes were found to be more numerous in hypertensive vessels. Biochemical assays of two specific lysosomal enzymes revealed a doubling of acid phosphatase and a more than threefold increase in beta-N-acetyl-glucosaminidase activities in hypertensive aortas.