Cerebral plasminogen activator activity in spontaneously hypertensive stroke-prone rats.

BACKGROUND AND PURPOSE In the spontaneously hypertensive stroke-prone rat, it is unclear whether plasminogen activator plays a role in the development of stroke. The present study was undertaken to investigate brain levels of plasminogen activator activity in spontaneously hypertensive stroke-prone rats and Wistar-Kyoto rats. METHODS Plasminogen activator was purified from the brains of rats of both strains. The purification involved used ammonium sulfate precipitation, gel filtration, a zinc chelate-Sepharose column, and a concanavalin A-Sepharose column. Fraction I (0.15 M KCl-soluble fraction) and fraction II (2 M KCl plus 6 M urea-soluble fraction) were purified from both strains. RESULTS Total plasminogen activator activity in the original homogenates for fractions I and II derived from spontaneously hypertensive stroke-prone rats was increased to twice the level found in Wistar-Kyoto rats. The final product purified from fractions I and II in both strains of rats revealed single bands of plasminogen activator activity on enzymatic analysis with a molecular weight of 72,000. The purified product had stronger S-2288 amidolytic activity than S-2444 amidolytic activity, and it also displayed fibrin-binding ability. CONCLUSIONS The study demonstrated that there is an increased content of plasminogen activator in the brains of spontaneously hypertensive stroke-prone rats that might be related to the development of stroke.