Paracellular glucose transport plays a minor role in the unanesthetized dog

John S. Lane, Edward E. Whang, David A. Rigberg, Oscar J. Hines, David Kwan, Michael J. Zinner, David W. McFadden, Jared Diamond, Stanley W. Ashley

Research output: Contribution to journalArticle

Abstract

Traditionally, intestinal glucose absorption was thought to occur through active, carrier-mediated transport. However, proponents of paracellular transport have argued that previous experiments neglected effects of solvent drag coming from high local concentrations of glucose at the brush-border membrane. The purpose of this study was to evaluate glucose absorption in the awake dog under conditions that would maximize any contribution of paracellular transport. Jejunal Thiry-Vella loops were constructed in six female mongrel dogs. After surgical recovery, isotonic buffers containing L-glucose as the probe for paracellular permeability were given over 2-h periods by constant infusion pump. At physiological concentrations of D-glucose (1-50 mM), the fractional absorption of L- glucose was only 4-7% of total glucose absorption. Infusion of supraphysiological concentrations (150 mM) of D-glucose, D-maltose, or D- mannitol yielded low-fractional absorptions of L-glucose (2-5%), so too did complex or nonabsorbable carbohydrates. In all experiments, there was significant fractional water absorption (5-19%), a prerequisite for solvent drag. Therefore, with even up to high concentrations of luminal carbohydrates in the presence of significant water absorption, the relative contribution of paracellular glucose absorption remained low.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume276
Issue number3 39-3
Publication statusPublished - 1999
Externally publishedYes

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Keywords

  • Cell membrane permeability
  • Maltose
  • Mannitol
  • Perfusion
  • Small intestine
  • Water absorption

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology
  • Physiology (medical)

Cite this

Lane, J. S., Whang, E. E., Rigberg, D. A., Hines, O. J., Kwan, D., Zinner, M. J., ... Ashley, S. W. (1999). Paracellular glucose transport plays a minor role in the unanesthetized dog. American Journal of Physiology - Gastrointestinal and Liver Physiology, 276(3 39-3).