Nitric oxide modulates renal vasoconstrictor effect of endothelin-1 in conscious lambs.
To test the hypothesis that nitric oxide (NO) buffers the renal vasoconstrictor effects of endothelin-1 (ET-1) early in life, renal haemodynamic responses to ET-1 were measured in the presence and absence of endogenously produced NO in conscious lambs. Renal haemodynamic effects of ET-1 were measured for 5 min before (control) and 20 min after intraarterial injection of ET-1 before and after pretreatment with 20 mg/kg of the L-arginine analogue N(G)-nitro-L-arginine methyl ester (L-NAME), (experiment 1) and its inactive isomer D-NAME (experiment 2) in conscious lambs aged approximately 1 week (N=7) and approximately 6 weeks (N=6). The two experiments were carried out in random order at intervals of 24-48 h. In lambs aged approximately 6 weeks, a marked increase in renal vascular resistance (RVR) was elicited by ET-1 administration; this response was enhanced twofold following pretreatment with L-NAME. In 1-week-old lambs, however, an increase in RVR in response to ET-1 occurred only after pretreatment with L-NAME. Therefore, we accept our hypothesis and conclude that NO buffers the renal vasoconstrictor effects of ET-1 early in life.
Smith
Francine G
FG
Department of Physiology & Biophysics/Medicine, University of Calgary, Calgary, Alberta, Canada. fsmith@ucalgary.ca
van der Velde
Liesbeth
L
Sener
Alp
A
D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000187:drug effects; D019332:Endothelin-1 / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007668:Kidney / Q000098:blood supply*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000494:pharmacology* / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000494:pharmacology; D012079:Renal Circulation / Q000187:drug effects; D012756:Sheep; D014655:Vascular Resistance; D014661:Vasoconstriction / Q000187:drug effects*; D014690:Venous Pressure / Q000187:drug effects
D019332:Endothelin-1; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester