Preserving the Autoregulation of Renal Hemodynamics

Abstract

Renal hemodynamics in essential hypertensives is characterized by an increase in renal vascular resistance (RVR) and a decrease in renal plasma flow (RPF), while glomerular filtration rate (GFR) is either normal or slightly decreased. Filtration fraction (FF) is increased, indicating that vasoconstriction predominantly affects postglomerular arteries. This increase in FF, called hyperfiltration, can be regarded as a successful maintenance of a normal glomerular filtration but can be deleterious for long-term renal function by favoring the development of glomerulosclerosis. Administration of some beta-blockers (especially propranolol) to hypertensive patients still reduces RPF and GFR, and increases FF. Conversely, in short-term studies, tertatolol has been shown to reduce RVR and increase RPF, without altering FF in hypertensive patients. These effects correspond to a normalization of the renal hemodynamic profile. Their practical interest is however strongly dependent on their persistance in long-term treatment. The beneficial effects of tertatolol were confirmed in 3 long-term studies, lasting for one year. These three studies yielded remarkably similar results: there was a modest overall decrease in serum creatinine, and a more pronounced drop in patients whose pretreatment renal function was altered. These data suggest that tertatolol may preserve the long-term autoregulation of renal hemodynamics. The possibility is raised that in patients with minimal renal dysfunction, tertatolol may also slow down the progression of renal failure.