Whole body and renal noradrenaline release during acute infusion of endothelin-1 in conscious sheep.
1. The present study investigated in conscious sheep the response of the sympathetic nervous system to a systemic infusion of 20 nmol/h endothelin-1 (ET-1), using a tritiated-noradrenaline (NA) tracer dilution technique. 2. Mean arterial pressure increased from 79 +/- 3 mmHg to a maximal level of 102 +/- 12 mmHg by 30 min of ET-1 infusion. 3. Total and renal NA kinetics were measured during this time. Total NA spillover was not affected by infusion of ET-1. In contrast, renal NA spillover decreased from a control level of 81 +/- 5 to 30 +/- 14 ng/min (P < 0.01) after 20 min and to 27 +/- 7 ng/min (P < 0.01) after 30 min of ET-1 infusion. 4. The present findings are consistent with the proposal that a direct vasoconstrictor action of ET-1 results in a paroreflex mediated reduction in renal sympathetic vasoconstrictor activity.
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Australia.
M L
ML
Mathai
J A
JA
Whitworth
J G
JG
McDougall
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D016232:Endothelins / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007262:Infusions, Intravenous; D007668:Kidney / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood / Q000378:metabolism*; D017596:Renal Plasma Flow, Effective / Q000187:drug effects; D012756:Sheep
D016232:Endothelins; D009638:Norepinephrine