Redistribution of Renal Blood Flow in Haemorrhagic Hypotension Role of Renal Nerves and Circulating Catecholamines* *.

Haemorrhagic hypotension (HH) causes a redistribution of intrarenal blood flow characterized by a patchy cortical hypoperfusion. Previous studies indicated that the sYmpathoadrenergic system is mainly responsible for these redistribution processes. The relative role of renal nerves and of circulating catecholamines was studied in the present experiments. Intrarenal haemodynamics were analysed by means of the 133 Xenon washout technique and 83 Krypton autoradiographics. 8 autotransplanted (and, therefore, chronically denervated) kidneys showed the same typical response to severe and prolonged HH as 11 normal control organs. In 2 additional dogs, the intrarenal distribution of blood flow (IDBF) and local blood flow rates (Fi ) of an acutely denervated kidney before and during HH did not show any differences as compared with the contralateral control organ. It is concluded that the patchy cortical hypoperfusion observed in the dog during severe haemorrhagic hypotension does not depend on an intact innervation of the kidney, but that it is mainly mediated by circulating catecholamines.