[Electrolyte metabolism in renal tubules]

Obese, diabetic and hypertensive populations have an increased prevalence of hyperinsulinemia and insulin resistance with respect to glucose metabolism. Insulin is thought to contribute to hypertension by sodium retention in the kidney. Here we describe the direct effect of insulin on renal tubular transport. The ascending thin limb of Henle's loop (ATL) plays an important role in concentrating urine. However, it is still controversial whether Na+ reabsorption in this nephron segment is an active process or a passive one. Moreover hormonal regulation of Cl- transport in the ATL is completely unknown. Therefore we also describe the mechanism of Na+ transport and hormonal regulation of Cl- transport in the ATL.