Enhancement of fibrinolysis in the dog by injection of vasoactive drugs

Abstract

Intravenous injection of epinephrine into the dog produces an increase in fibrinolytic activity of plasma euglobulins. This increase appears to be unrelated to the following epinephrine-induced effects: splenic contraction, stimulation of the lymph circulation, increase in blood glucose, lactic acid, or free fatty acids. A specific involvement of either alpha or beta adrenotropic receptors is ruled out since norepinephrine and isopropylnorepinephrine are equally effective in enhancing fibrinolysis. Intravenous injection of each of a number of vasoactive drugs with different modes of action, and with either hypertensive or hypotensive properties, induces an increase in fibrinolytic activity. Hence, it appears that there is a direct relationship between appearance of increased fibrinolytic activity and vasoactive changes. For all the drugs tested except methoxamine, the maximal fibrinolytic effect is present 5 min after the injection and in general the fibrinolytic activity returns to the preinjection level within 30 min. Repeated injections of a powerful inducer of increased fibrinolytic activity, such as histamine, results in a progressive decrease of the fibrinolytic response.