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Capillary filtration coefficient is independent of number of perfused capillaries in cat skeletal muscle

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Author

Summary, in English

The capillary filtration coefficient (CFC) is assumed to reflect both microvascular hydraulic conductivity and the number of perfused capillaries at a given moment (precapillary sphincter activity). Estimation of hydraulic conductivity in vivo with the CFC method has therefore been performed under conditions of unchanged vascular tone and metabolic influence. There are studies, however, that did not show any change in CFC after changes in vascular tone and metabolic influence, and these studies indicate that CFC may not be influenced by alteration in the number of perfused capillaries. The present study reexamined to what extent CFC in a pressure-controlled preparation depends on the vascular tone and number of perfused capillaries by analyzing how CFC is influenced by 1) vasoconstriction, 2) increase in metabolic influence by decrease in arterial blood pressure, and 3) occlusion of precapillary microvessels by arterial infusion of microspheres. CFC was calculated from the filtration rate induced by a fixed decrease in tissue pressure. Vascular tone was increased in two steps by norepinephrine (n = 7) or angiotensin II (n = 6), causing a blood flow reduction from 7.2 +/- 0.8 to at most 2.7 +/- 0.2 ml . min(-1) . 100 g(-1) (P< 0.05). The decrease in arterial pressure reduced blood flow from 4.8 +/- 0.4 to 1.40 +/- 0.1 ml . min(-1) . 100 g(-1) (n = 6). Vascular resistance increased to 990 +/- 260% of control after the infusion of microspheres (n = 6). CFC was not significantly altered from control after any of the experimental interventions. We conclude that CFC under these conditions is independent of the vascular tone and number of perfused capillaries and that variation in CFC reflects variation in microvascular hydraulic conductivity.

Publishing year

2001

Language

English

Pages

2697-2706

Publication/Series

American Journal of Physiology: Heart and Circulatory Physiology

Volume

280

Issue

6

Document type

Journal article

Publisher

American Physiological Society

Topic

  • Physiology

Status

Published

ISBN/ISSN/Other

  • ISSN: 1522-1539