Effects of dilazep on fibrinolytic system in animals. II. Enhancing effect of dilazep on plasminogen activator release in the isolated perfused pig ear.

The influence of drugs on the release of plasminogen activator was studied in the isolated perfused pig ear. The pig ear was perfused with oxygenated Tyrode's solution pH 7 . 4, at 37 degrees C via main artery and perfusate from the veins was collected at 2 min intervals. The drug was injected into a rubber tube connected in the front of arteria cannula, and the fibrinolytic activity of perfusate collected was measured by the fibrin plate method using plasminogen-containing bovine fibrinogen. Under the test condition, dilazep enhanced plasminogen activator release (PA release) in a dose-dependent fashion ranging 10 to 100 microgram, however, it did not affect the perfusion pressure. Hypotensors, namely acetylcholine (0.1-3 microgram), bradykinin (0.1-3 microgram) and histamine (0.1-3 microgram) enhanced also the PA release in a dose-dependent fashion with no effects on perfusion pressure. Vasoconstricting drugs, namely phenylephrine (0.3-10 microgram), norepinephrine (0.1-3 microgram) and serotonin (0.1-3 microgram) exerted hypertensive effects on perfusion pressure in a dose-dependent fashion, however, it did not cause the PA release.