Renal mechanisms of genetic hypertension: From the molecular level to the intact organism

Human primary hypertension is a polygenic disease; its phenotypic expression is modulated by the environment. Though the kidney can play a major role in the initiation and maintainance of hypertension, many questions remain open. Kidney cross-transplantation demonstrated that hypertension can be transplanted with the kidney in all strains of genetically hypertensive rats where such experiments have been carried out. Data consistent with those in rats were also obtained in humans. Many abnormalities in kidney function and ion transport were described in hypertensive rats and humans, but the logical sequence from genetic-molecular to cellular abnormality that causes hypertension via modification of kidney function is difficult to prove. We established this sequence in Milan hypertensive rats using a variety of experimental techniques (isolated kidney and renal cell function, cell membrane ion transport, cross-immunization with membrane proteins, molecular biology, genetic crosses and manipulation). Such studies led to the identification of a polymorphism in the cytoskeletal protein adducin. This polymorphism seems involved in blood pressure regulation both in rats and humans. Preliminary results suggest that adducin polymorphism affects kidney function by modulating the overall capacity of tubular epithelial cells to transport ions modifying the assembly of actin cytoskeleton.