In vivo effect of alpha 1-acid glycoprotein on experimentally enhanced capillary permeability in guinea-pig skin.

Anesthetized guinea-pigs were intravenously injected with Evans blue. After intracutaneous injection of agonists (lys-plasminogen, histamine, platelet-activating factor, thrombin, bradykinin), the resulting wheals appeared blue in a dose-dependent manner, due to an enhanced capillary permeability, alpha 1-Acid glycoprotein, given i.v. in different doses (3.125-50 mg/kg) and at different times (30-180 min) before Evans blue administration, antagonized the effects of all agonists listed above. This was shown by a parallel shift of the agonist dose-response curves to the right. The effect was time-dependent (tmax: mainly 120 min) and dose-dependent. alpha 1-Acid glycoprotein antagonized the agonists in the following order: lys-plasminogen > histamine = platelet-activating factor > thrombin > bradykinin. As all agonist mentioned are suggested to play a major role in the shock-related increase in vascular permeability, a putatively beneficial role of alpha1-acid glycoprotein in shock is discussed.