Tubular Alterations Produced by Osmotic Diuresis with Mannitol

Abstract

The effects of mannitol on renal morphology and function were studied in dogs. An infusion of 10% mannitol was given at 10cc/min. for 70 minutes. Serial renal biopsies were taken at 15, 45 and 70 minutes and at 24, 48 and 96 hours after the onset of the infusion. The tissue was examined by light and electron microscopy. The anatomical changes were striking and confined to the proximal tubules. Specimens examined by electron microscopy at 15 minutes showed poorly defined areas of cytoplasm beneath brush border which had the appearance of early vacuoles. At 45 minutes, distinct large vacuoles containing amorphous material were present which occupied a large portion of the cytoplasm. At 70 minutes, many of these vacuoles contained dense osmiophilic material and were otherwise clear. At 24 hours, the vacuoles were smaller, increased in number, and appeared to occupy the greater part of the cytoplasm. At 48 hours they began to regress and at 96 hours the tissue was similar to the control except for a slight increase in vacuoles. Despite the prominent anatomical change, renal function measurements including GFR, [glomerular filtration rate] TmPAH, [tubular paraamine hippurate] CH2O [formaldehyde] electrolyte excretion made prior to and 24 hours after the infusion were similar.[long dash]Authors.