Journal of Applied Physiology, Vol 55, Issue 4 1079-1084, Copyright © 1983 by American Physiological Society
Effect of bradykinin on lung vascular permeability in sheep
F. L. Minnear, C. M. Kivlen and A. B. Malik
Bradykinin (BK, 0.03-3.11 micrograms X kg-1 X min-1) was infused
intravenously for 4-5.5 h to assess its effects on pulmonary transvascular
fluid and protein exchange in three groups of artificially ventilated sheep
prepared with lung lymph fistulas. In group I, BK was infused alone for 5.5
h. In group II, BK and captopril (SQ 14,225), an inhibitor of
angiotensin-converting enzyme (ACE), were infused together because the
effects of BK may be attenuated by its rapid degradation in the lung by
ACE. In group III, BK was infused in the presence of propranolol, a
beta-adrenergic antagonist, to prevent any permeability-decreasing effects
of beta-adrenergic activation. The dosages of BK used, which decreased
systemic arterial blood pressure by 10-20 mmHg, did not alter either
pulmonary transvascular fluid and protein exchange or pulmonary
hemodynamics at any time during infusion of BK alone or in combination with
captopril or propranolol. Raising pulmonary microvascular pressure (Pmv) by
inflating a left atrial balloon during the last 2 h of infusion in all
three groups slightly increased pulmonary lymph flow and markedly decreased
the lymph-to-plasma protein concentration ratio. These results are
comparable with those obtained after increasing Pmv in normal anesthetized
sheep and indicate that BK did not alter the pulmonary vascular
permeability to proteins.
