Adrenergic Mechanisms in the Systemic Plasminogen Activator Response to Adrenaline in Man

S ummary . The effect of propranolol, ICI 50172 and a combination of propranolol and phentolamine, on the plasminogen activator response to a 30 mm intravenous infusion of adrenaline hydrochloride (0.1 μg/kg/min) has been studied in five healthy subjects. Plasma factor VIII, serum free fatty acids, blood glucose and pulse rate changes were also monitored to confirm the efficacy of adrenergic blockade. Propranolol blocked the plasminogen activator response by a factor of 29% whereas ICI 50172 had no effect. The addition of phentolamine to propranolol failed to influence further the degree of blockade already present with propranolol alone. It is postulated that the plasminogen activator response to adrenaline is derived from two separate components, and that the relatively minor one may be secondary to vasoactive changes whereas the second and major component is quite independent of this phenomenon. It is also proposed that both components may share a common adrenergic receptor site.