The effects of glucose and parathyroid hormone (PTH) on the transport and metabolism of myoinositol (MI) and [2-3H]MI were studied in isolated perfused dog kidneys. Studies during perfusion of kidneys with normal and elevated glucose concentrations demonstrated that under normal conditions the isolated kidney reabsorbed 94.7±0.2% of the filtered MI, and the renal production of 3H-metabolities of MI was 117.9±6% of the filtered MI load. This indicated that entry of MI into tubular cells by reabsorption was not the sole pathway for entry into the pool of MI within the kidney undergoing catabolism. High glucose perfusate decreased MI reabsorption to 68.6±4.7% and thus decreased delivery of [2-3H]MI into the catabolic pool from the reabsorptive pathway. In the high glucose experiments, the rate of [2-3H]MI catabolism exceeded [2-3H]MI reabsorption by the same fraction as in normal glucose experiments, which indicates that high glucose did not affect nonreabsorptive access of MI to the catabolic site.
B. A. Molitoris, K. A. Hruska, N. Fishman, W. H. Daughaday