Localization and rapid regulation of Na+/myo-inositol cotransporter in rat kidney.

摘要: myo-inositol, a major compatible osmolyte in renal medulla, is accumulated several kinds of cells under hypertonic conditions via Na+/myo-inositol cotransporter (SMIT). To investigate the physiological role SMIT, we sought to determine its localization by situ hybridization and acute regulation NaCl furosemide administration. Northern analysis demonstrated that SMIT strongly expressed medulla at low levels cortex kidney. Intraperitoneal injection rapidly induced mRNA both completely abolished this induction. In revealed it predominantly present medullary cortical thick ascending limbs Henle's loop (TALH) macula densa cells. Less intense signals were seen inner collecting ducts (IMCD). loading increased throughout TALH, reduced signals. IMCD less sensitive these regulation. Thus, distribution pattern does not correspond corticomedullary osmotic gradient, TALH regulated very rapidly. These results suggest expression may be intracellular and/or peritubular tonicity close basolateral membrane, which supposed proportional magnitude reabsorption.