Vascular permeability and interstitial diffusion of macromolecules in the hamster cheek pouch: effects of vasoactive drugs.

A simple one-dimensional mathematical model which relates the number of "leaky" sites in postcapillary venules to the extravasation of macromolecules in terms of an effective microvascular permeability, P, and an effective interstitial diffusion coefficient, D, is developed. The model is used to analyze the data of E. Svensjö and K. Roempke [in "Progress in Microvascular Research II" (F. C. Courtice, D. C. Garlick, and M. A. Perry, Eds.), pp. 449-463, 1984] and C. G. A. Persson and E. Svensjö [in "Handbook of Inflammation" (J. L. Bonta, M. A. Bray, and M. J. Parnham, Eds.), pp. 61-82, 1985] for the transport of 70,000 molecular weight dextran in a hamster cheek pouch prior to and following topical application of two vasoactive agents: histamine and bradykinin. D ranged from 2.2 to 4.0 X 10(-9) cm2/sec, and P was found to be 4.1 X 10(-8) cm/sec. The increased number of leaky sites resulted in a sixfold increase in P due to histamine, at a dose of 2.5 X 10(-6) M, and a fourfold increase in P due to bradykinin, at a dose of 4.0 X 10(-7) M.