PRESERVING THE AUTOREGULATION OF RENAL HEMODYNAMICS

Renal hemodynamics in essential hypertensives is characterized by an i ncrease in renal vascular resistance (RVR) and a decrease in renal pla sma flow (RPF), while glomerular filtration rate (GFR) is either norma l or slightly decreased. Filtration fraction (FF) is increased, indica ting that vasoconstriction predominantly affects postglomerular arteri es. This increase in FF, called hyperfiltration, can be regarded as a successful maintenance of a normal glomerular filtration but can be de leterious for long-term renal function by favoring the development of glomerulosclerosis. Administration of some beta-blockers (especially p ropranolol) to hypertensive patients still reduces RPF and GFR, and in creases FF. Conversely, in short-term studies, tertatolol has been sho wn to reduce RVR and increase RPF, without altering FF in hypertensive patients. These effects correspond to a normalization of the renal he modynamic profile. Their practical interest is however strongly depend ent on their persistance in long-term treatment. The beneficial effect s of tertatolol were confirmed in 3 long-term studies, lasting for one year. These three studies yielded remarkably similar results: there w as a modest overall decrease in serum creatinine, and a more pronounce d drop in patients whose pretreatment renal function was altered. Thes e data suggest that tertatolol may preserve the long-term autoregulati on of renal hemodynamics. The possibility is raised that in patients w ith minimal renal dysfunction, tertatolol may also slow down the progr ession of renal failure.