Resting oxygenation of rat and rabbit intestine: Arteriolar and capillary contributions

H. G. Bohlen, J. M. Lash

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Counter-current exchange of oxygen may occur between inflow and outflow microvessels of the small intestine and greatly influence the dominant sites of tissue oxygenation. To determine the location and magnitude of potential exchange, percent saturation of hemoglobin with oxygen (%S(Hb)) was measured in microvessels throughout the intestine of rats and rabbits. Oxygen losses from systemic arterial blood through large and intermediate arterioles (second order, 2A) was 5-7%S(Hb) in both species, and there was no evidence of an increase in percent saturation along intermediate and large venules. A larger loss of oxygen from arterioles and an increase in venous saturation would be evident if significant arteriolar to venular counter-current exchange of oxygen occurred in the submucosa. From 2A to the villus tip, arteriolar saturation decreased ~10%S(Hb) in rabbits and ~15%S(Hb) in rats the villus tip percent saturation was 72.9 ± 3.9%S(Hb) in rabbits and 69.9 ± 2.9%S(Hb) in rats. An additional decrease of 5%S(Hb) in rabbits and 15%S(Hb) in rats occurred across the villus capillaries and smallest venules. Although the total reduction in percent saturation across the villi was different between the two species, 70-90% of the total arteriovenous oxygen losses occurred in the capillaries and small arterioles of the villi. We found no evidence of counter-current exchange of oxygen in villi or any other vascular region. Rather, as appears to occur in most organs, small arterioles in conjunction with capillaries dominate resting oxygen exchange to tissue.

Original languageEnglish (US)
Pages (from-to)H1342-H1348
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume269
Issue number4 38-4
StatePublished - Jan 1 1995

Keywords

  • microcirculation
  • oxygen exchange

ASJC Scopus subject areas

  • Physiology

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