Lysosomal Enzyme Activity in the Arterial System in SHRSP

In an attempt to obtain information about the arterial lysosomal enzymes in chronic hypertension, we investigated acid phosphatase (Ac-Pase) activity in the arterial system in SHRSP histochemically, cytochemically as well as biochemically. In the histochemical and biochemical studies, Ac-Pase activity in SHRSP was always higher than in age-matched WKY. The activity tended to increase with advancing age, a tendency which was more pronounced in SHRSP than WKY. Antihypertensive drugs significantly suppressed the rise of blood pressure and decreased the aortic Ac-Pase activity in SHRSP. Reserpine and propranolol lowered Ac-Pase activity more effectively than it did blood pressure. Hypertension as well as catecholamine seem to be involved in the increase in the arterial lysosomal enzyme activity in SHRSP. In the cytochemical study, lytic changes of the arterial mural cells and vessel matrix due to lysosomal enzymes were also evident. Lysosomes in the arterial mural cells seem to play an important role in the development of hypertensive vascular changes.