Possible involvement of vasopressin and urine concentrating process in the progression of chronic renal failure

Abstract

This paper reviews experimental findings which support the concept that vasopressin (VP) and the process of urine concentration may be involved in the progression of chronic renal failure (CRF). The influence of dietary protein intake on the progression of CRF may also involve VP and the operation of the concentrating process. VP receptors have been identified in glomeruli and VP is able to constrict mesangial cells as does angiotensin II. Acute VP infusion increases the glomerular transcapillary hydraulic pressure difference, and chronic VP infusion increases GFR. In rats with CRF (induced by 5/6 nephrectomy), VP levels were found elevated. In rats with 5/6 nephrectomy, we increased experimentally water intake in order to decrease circulating VP levels, urine concentration, and free water reabsorption. Several indices of progression of CRF, including proteinuria, hypertension and glomerulosclerosis, were significantly reduced, thus suggesting a contribution of VP in progression. Lowering protein intake in CRF could be beneficial because proteins, but not carbohydrates or lipids, produce metabolic end products (mainly urea, ammonia, protons, etc.) that are excreted by the kidney, and concentrated in the urine. In healthy subjects (man or rat), high protein (HP) intake favors urine concentration and causes changes in kidney function and morphology very similar to those induced by chronic VP infusion or water restriction. These changes involve an increase in transport activity of the thick ascending limb (where the initial active step of the concentrating process takes place) and may affect filtration rate and/or glomerular hemodynamics secondarily, by decreasing salt concentration at the macula densa and depressing tubuloglomerular feedback.(ABSTRACT TRUNCATED AT 250 WORDS)