Neonatal 6-hydroxydopamine treatment and the development of renal hypertension in the rat.

Abstract

The onset and development of 2 kidney-2 clip renal hypertension was studied in chronically sympathectomized rats treated with 6-hydroxydopamine (6-OHDA) immediately after birth and with adrenal demedullation performed at the time of clipping. Blood pressure (BP) was lower in 6-OHDA treated animals than in untreated controls and the rate of hypertension development was similar in both groups. Urinary excretion of norepinephrine (NE) was significantly decreased during the 15th week and normal by the end of the 20th week. The cardiac NE content reached negligible levels while the mesenteric arteries retained 50% of its content. In the central nervous system (CNS) the 6-OHDA treatment induced a significant increase in NE concentration in the brain stem and medulla oblongata and a significant decrease in cerebellum. Hypertension produced a significant decrease in NE content in the brain stem while 6-OHDA treatment in hypertensive rats resulted in a generalized NE depletion in all the CNS areas. Results have shown that 6-OHDA treatment does not produce a complete and generally distributed sympathectomy; treatment reduces the level of BP but does not change the slope in BP increase.