Myo-inositol uptake by rat cultured inner medullary collecting tubule cells: Effect of osmolality

Judith H. Veis, Bruce Molitoris, Isaac Teitelbaum, Julie A. Mansour, Tomas Berl

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Myo-inositol (MI) is involved in the adaptation to hyperosmolality. Its uptake by rat inner medullary collecting duct (RIMCD) cells has not been studied. Compared with cells grown in isotonic media, those grown in hyperosmolality display marked enhancement in [3H]MI uptake [counts/min (cpm)·μg protein-1·2 h-1] from 217 ± 23 to 718 ± 64, P <0.001. This is mimicked by the supplementation with 300 mM mannitol (638 ± 59, P <0.001) but not by 300 mM urea. The increment in [3H]MI is observed at 37°C but not at 4°C. MI uptake is Na+ dependent in cells grown both in hyperosmolal or isotonic media. At least 12 h of hyperosmolality are needed to enhance MI uptake, and reexposure to isotonic media for at least 24 h is required for the enhancement to reverse. The effects of the microtubular inhibitor, nocodazole (10 μg/ml), and the protein synthesis inhibitor, cycloheximide (30 μg/ml), were studied. Cells grown with nocodazole show unimpaired enhancement of MI uptake. Cycloheximide exposure (16 h) does not affect MI uptake in isotonic media (182 ± 23 vs. 191 ± 15), but inhibited enhanced MI uptake in hyperosmolality (822 ± 53 in the absence vs. 331 ± 24 in the presence of cycloheximide, P <0.001). We conclude that hyperosmolality stimulates the synthesis of a protein, most likely an Na-MI cotransporter, that markedly enhances MI uptake. This process may be critical to the osmoregulation of RIMCD cells.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume260
Issue number5 29-5
StatePublished - 1991
Externally publishedYes

Fingerprint

Inositol
Osmolar Concentration
Cycloheximide
Nocodazole
Osmoregulation
Protein Synthesis Inhibitors
Mannitol
Urea
Proteins

Keywords

  • Cotransporter
  • Protein synthesis

ASJC Scopus subject areas

  • Physiology

Cite this

Myo-inositol uptake by rat cultured inner medullary collecting tubule cells : Effect of osmolality. / Veis, Judith H.; Molitoris, Bruce; Teitelbaum, Isaac; Mansour, Julie A.; Berl, Tomas.

In: American Journal of Physiology - Renal Fluid and Electrolyte Physiology, Vol. 260, No. 5 29-5, 1991.

Research output: Contribution to journalArticle

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