Effects of chronic hypoxia on capillary flow and hematocrit in rat skeletal muscle.

Published

Journal Article

The cremasteric microcirculation was studied in rats exposed to chronic hypoxia. Control male weanling Sprague-Dawley rats (n = 8) were raised for 42-49 days at 752 mmHg. Hypoxic rats (n = 9) were reared for 3 days at 551 mmHg, 4 days at 461 mmHg, 3 days at 371 mmHg, and 31-38 days at 311 mmHg (6,000 m). Red blood cells labeled with fluorescein isothiocyanate were injected. The exposed cremaster was observed using fluorescence microscopy. Rats acutely breathed 10, 21, and 30% O2 spontaneously in random order. Hypoxia-adapted animals had greater (P less than 0.01) red cell flux (10.6 +/- 1.0 vs. 5.7 +/- 0.4/s), capillary hematocrits, capillary-to-systemic hematocrit ratios (0.42 +/- 0.02 vs. 0.33 +/- 0.02), and reduced red cell spacing (11.4 +/- 1.3 vs. 22.3 +/- 2.0 microns) than controls under 21% O2. Chronically hypoxic rats also demonstrated significantly (P less than 0.05) larger capillary diameters (6.52 +/- 0.04 vs. 6.15 +/- 0.06 microns) and greater perfused (135 +/- 5 vs. 94 +/- 3 mm/mm3) and anatomic (182 +/- 5 vs. 151 +/- 8 mm/mm3) microvessel length-densities at 21% O2. Results were generally similar for 10 and 30% O2. Bulk capillary blood flow was significantly (P less than 0.01) greater in controls (2.75 +/- 0.32 vs. 1.87 +/- 0.12 pl/s) only under 30% O2. Our experiments demonstrate that numerous physiological, in addition to anatomic, alterations can occur in the cremasteric microcirculation in response to chronic hypoxia.

Full Text

Duke Authors

Cited Authors

  • Fisher, AJ; Schrader, NW; Klitzman, B

Published Date

  • June 1992

Published In

Volume / Issue

  • 262 / 6 Pt 2

Start / End Page

  • H1877 - H1883

PubMed ID

  • 1621845

Pubmed Central ID

  • 1621845

International Standard Serial Number (ISSN)

  • 0002-9513

Digital Object Identifier (DOI)

  • 10.1152/ajpheart.1992.262.6.H1877

Language

  • eng

Conference Location

  • United States