AJP - Heart and Circulatory Physiology, Vol 258, Issue 5 1321-H1333, Copyright © 1990 by American Physiological Society
Endothelial and epithelial permeabilities to antipyrine in rat and dog lungs
W. O. Cua, G. Basset, F. Bouchonnet, R. A. Garrick, G. Saumon and F. P. Chinard
Department of Medicine, University of Medicine and Dentistry, New Jersey Medical School, Newark 07103-2757.
Temperature effects on the permeabilities of the structured endothelium and
epithelium to antipyrine (AP) have been determined with the indicator
dilution technique in isolated rat and dog lungs perfused between 38 and 8
degrees C. Permeability coefficients of the endothelium to AP [Pendo(AP)]
from the Crone equation are smaller than values for isolated endothelial
cells but close to the permeability coefficient of the interstitial
epithelial plasmalemma [Pepi(AP)] obtained from physical and mathematical
models. In these, tracer water is flow limited at the endothelium and the
epithelium at all temperatures; AP is flow limited at the endothelium at T
greater than 20 degrees C but barrier limited at the endothelium for T less
than 20 degrees C and at the epithelium at all temperatures. At T less than
20 degrees C, log Pendo(AP) decreases regularly with 1/T, with a slope
close to that found in cultured bovine pulmonary artery endothelial cells.
At 15 degrees C, Pendo(AP) for the endothelial plasmalemma in situ is 30 X
10(-5) cm/s and is 56 X 10(-5) cm/s for the isolated cells in support of
transcellular rather than paracellular passage. At T greater than 20
degrees C, log Pepi(AP) in situ decreases slightly with 1/T, with a
discontinuity at T = 20 degrees C, and for T less than 20 degrees C,
decreases with 1/T with a slope close to that of Pendo(AP). At 15 degrees
C, Pepi(AP) is 2.8 X 10(-5) cm/s. The discontinuity may represent a change
in the physical state of lipids in the interstitial plasmalemma of the
epithelial cells.
