Development of solute transport in rabbit proximal tubule. I. HCO3- and glucose absorption

G. J. Schwartz, Andrew Evan

Research output: Chapter in Book/Report/Conference proceedingChapter

69 Citations (Scopus)

Abstract

Infants have a lower renal threshold for HCO3- than adults. To determine whether this phenomenon is due to factors intrinsic to the tubular transporting systems, we measured absorption rates of fluid [J(V)] and HCO3- [J(HCO3-)] in isolated perfused early proximal convoluted tubules (JMPCT) taken from the juxtamedullary renal cortex of developing rabbits. Artificial solutions simulating plasma ultrafiltrate were used to perfuse and bathe the tubule. The bath also contained 6 g/dl albumin. Electron microscopy confirmed that each JMPCT was S1. During the 1st 4 wk of postnatal life, J(V) and J(HCO3-) changed relatively little, averaging 0.39 ± 0.03 nl·min-1·mm-1 and 32.4 ± 2.6 pmol·min-1·mm-1, respectively. An increase of more than 100% was observed in J(V) and J(HCO3-)-during the 5th and 6th wk to 0.80 ± 0.06 and 67.5 ± 8.0, respectively, levels nearly equal to those observed in JMPCT obtained from adult rabbits (1.27 ± 0.17 and 89.4 ± 18.0, respectively). Because J(HCO3-) is mediated by Na+-H+ exchange and dependent on low cell Na+, we examined the development of another Na+-dependent lumen-to-bath transport system, that for glucose [J(Glc)]. The maturational pattern was similar, with J(Glc) averaging 34.1 ± 2.4 pmol·min-1·mm-1 during the 1st 4 wk of life and then increasing 70% to 56.7 ± 5.3 by 5-6 wk of age. We conclude that the rapid increases in the rate of fluid, HCO3-, and glucose transport follow by approximately 1 wk the maturational changes in the surface areas of the apical, mitochondrial, and basolateral membranes. We hypothesize that the development of either the rate of nephron filtration, the number of luminal Na+ transporters, or the activity of basolateral Na+-extruding pumps may mediate the changes in solute transport observed in the maturing proximal tubule.

Original languageEnglish (US)
Title of host publicationAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume14
Edition3
StatePublished - 1983
Externally publishedYes

Fingerprint

Baths
Rabbits
Kidney
Glucose
Intrinsic Factor
Nephrons
Mitochondrial Membranes
Albumins
Electron Microscopy

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Schwartz, G. J., & Evan, A. (1983). Development of solute transport in rabbit proximal tubule. I. HCO3- and glucose absorption. In American Journal of Physiology - Renal Fluid and Electrolyte Physiology (3 ed., Vol. 14)

Development of solute transport in rabbit proximal tubule. I. HCO3- and glucose absorption. / Schwartz, G. J.; Evan, Andrew.

American Journal of Physiology - Renal Fluid and Electrolyte Physiology. Vol. 14 3. ed. 1983.

Research output: Chapter in Book/Report/Conference proceedingChapter

Schwartz, GJ & Evan, A 1983, Development of solute transport in rabbit proximal tubule. I. HCO3- and glucose absorption. in American Journal of Physiology - Renal Fluid and Electrolyte Physiology. 3 edn, vol. 14.
Schwartz GJ, Evan A. Development of solute transport in rabbit proximal tubule. I. HCO3- and glucose absorption. In American Journal of Physiology - Renal Fluid and Electrolyte Physiology. 3 ed. Vol. 14. 1983
Schwartz, G. J. ; Evan, Andrew. / Development of solute transport in rabbit proximal tubule. I. HCO3- and glucose absorption. American Journal of Physiology - Renal Fluid and Electrolyte Physiology. Vol. 14 3. ed. 1983.
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