TY - JOUR
T1 - Tubular reabsorption of myo-inositol vs. that of D-glucose in rat kidney in vivo et situ
AU - Silbernagl, Stefan
AU - Völker, Katharina
AU - Dantzler, William H.
PY - 2003/6/1
Y1 - 2003/6/1
N2 - Filtered myo-inositol, an important renal intracellular organic osmolyte, is almost completely reabsorbed. To examine tubule sites and specificity and, thus possible mechanism of this reabsorption, we microinfused myo-[3H]inositol or D-[3H]glucose into early proximal (EP), late proximal (LP), or early distal tubule sections of superficial nephrons and into long loops of Henle (LLH) of juxtamedullary nephrons and papillary vasa recta in rats in vivo et situ and determined urinary fractional recovery of the 3H label compared with comicroinfused [14C]inulin. To determine the extent to which the proximal convoluted tubule (PCT) alone contributes to myo-inositol reabsorption, we also microperfused this tubule segment between EP and LP puncture sites. We examined specificity of reabsorptive carrier(s) by adding high concentrations of other polyols and monosaccharides to the infusate. The results show that >60% of the physiological glomerular load of myo-inositol can be reabsorbed in the PCT and >90% in the short loop of Henle (SLH) by a saturable, phloridzin-sensitive process. myo-Inositol can also be reabsorbed in the ascending limb of LLH and can move from papillary vasa recta blood into ipsilateral tubular structures. Essentially no reabsorption occurred in nephron segments beyond the SLH or in collecting ducts. Specificity studies indicate that reabsorption probably occurs via a luminal Na+-myo-inositol cotransporter.
AB - Filtered myo-inositol, an important renal intracellular organic osmolyte, is almost completely reabsorbed. To examine tubule sites and specificity and, thus possible mechanism of this reabsorption, we microinfused myo-[3H]inositol or D-[3H]glucose into early proximal (EP), late proximal (LP), or early distal tubule sections of superficial nephrons and into long loops of Henle (LLH) of juxtamedullary nephrons and papillary vasa recta in rats in vivo et situ and determined urinary fractional recovery of the 3H label compared with comicroinfused [14C]inulin. To determine the extent to which the proximal convoluted tubule (PCT) alone contributes to myo-inositol reabsorption, we also microperfused this tubule segment between EP and LP puncture sites. We examined specificity of reabsorptive carrier(s) by adding high concentrations of other polyols and monosaccharides to the infusate. The results show that >60% of the physiological glomerular load of myo-inositol can be reabsorbed in the PCT and >90% in the short loop of Henle (SLH) by a saturable, phloridzin-sensitive process. myo-Inositol can also be reabsorbed in the ascending limb of LLH and can move from papillary vasa recta blood into ipsilateral tubular structures. Essentially no reabsorption occurred in nephron segments beyond the SLH or in collecting ducts. Specificity studies indicate that reabsorption probably occurs via a luminal Na+-myo-inositol cotransporter.
KW - D-glucose transport
KW - Myo-inositol transport
KW - Sodium-myo-inositol cotransporter
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U2 - 10.1152/ajprenal.00395.2002
DO - 10.1152/ajprenal.00395.2002
M3 - Article
C2 - 12736166
AN - SCOPUS:0037609580
SN - 0363-6127
VL - 284
SP - F1181-F1189
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 6 53-6
ER -