AJP - Heart and Circulatory Physiology, Vol 249, Issue 3 498-H504, Copyright © 1985 by American Physiological Society
Microvascular pressure, surface area, and permeability in isolated hindquarters of SHR
R. J. Korthuis, C. R. Kerr, M. I. Townsley and A. E. Taylor
The transvascular escape rate (TER) of labeled albumin is reported to
increase in essential hypertension. However, the mechanism for this
augmented rate of protein efflux is uncertain and may be related to
increased microvascular permeability, surface area, and/or pressure. To
determine the possible contributions of these mechanisms to increased TER
of protein, the osmotic reflection coefficient for total plasma protein,
capillary filtration coefficient, and effective capillary pressure were
estimated in isolated hindquarters of age-matched (12-13 wk) spontaneously
hypertensive (SHR), Wistar-Kyoto (WKY), and Wistar (WR) rats. Estimates of
the reflection and filtration coefficients were not significantly different
in SHR, WKY, and WR. However, capillary pressure was significantly greater
in SHR than in normotensive controls. These results indicate that 1)
skeletal muscle microvascular permeability and surface area are similar in
SHR, WKY, and WR; 2) effective capillary pressure is greater in SHR than
WKY or WR; and 3) if TER for protein is elevated in hypertensive skeletal
muscle, the primary mechanism for this process may be increased convective
transport of protein secondary to elevated microvascular hydrostatic
pressure.
