<prompt> Mannitol produces diuresis by-Osmotic effectInhibition of Na K 2CLInhibition of Na KInhibition of aquaporin channels  <response>: Ans. is a i.e., Osmotic effect Mannitol It is a nonelectrolyte of low molecular weight that is pharmacologically inert. It raises osmolarity of plasma and tubular fluid. Blood viscosity is decreased. Mannitol decreases tubular water and electrolyte reabsorption by -1. Due to osmotic effect, fluid is retained in the lumen of PT.2. Inhibits transport processes in thick ascending limb - most important cause of diuresis.3. Expands ECF t intravascular volume - draws water from the intracellular compartment - increases GFR and inhibits renin release.4. Increases renal blood flow, especially to medulla - medullary hypertonicity is reduced - corticomedullary osmotic gradient is dissipated passive salt reabsortion is reduced. Uses - Raised IOT glaucoma, raised ICT, to maintain. GFR and urine flow in impending renal failure, and to counteract low osmolality of plasmaECF due to rapid hemodialysis. Contraindications - Acute tubular necrosis ARF, anuria, pulmonary edema, Acute LVF, cerebral hemorrhage edema. 