Abstract

Local intra-arterial infusions of bradykinin into canine forelimbs perfused either naturally or at constant inflow markedly increase skin lymph protein concentration promoting edema formation. However, prolonged systemic infusions of this agent either intravenously or into the left ventricular chamber, in blood concentrations calculated to exceed those that produce massive protein and fluid efflux on local administration, causes only minimal increases in lymph protein concentration, and in naturally perfused forelimbs promotes extravascular fluid reabsorption rather than net fluid filtration. Local infusions of bradykinin fail to alter aortic pressure whereas systemic infusions produce a profound but transient decrease in this variable. Moreover, the local intra-arterial infusion of bradykinin into forelimbs perfused at constant inflow fails to increase skin lymph protein concentration after 60 minutes of systemic hypotension. In contrast to bradykinin alone, the simultaneous infusion of bradykinin and norepinephrine or bradykinin and isoproterenol fails to increase skin lymph protein concentration. The antagonism of the bradykinin protein efflux by both norepinephrine and isoproterenol can be prevented by prior treatment with propranolol. These data suggest that the liberation of catecholamines may account, in part, for the minimal increases in forelimb protein efflux during systemic infusions of bradykinin relative to that produced by local intra-arterial infusions of this agent.