Prostaglandins and nitric oxide in regional kidney blood flow responses to renal nerve stimulation.
We examined the roles of cyclooxygenase products and of interactions between the cyclooxygenase and nitric oxide systems in the mechanisms underlying the relative insensitivity of medullary perfusion to renal nerve stimulation (RNS) in anaesthetized rabbits. To this end we examined the effects of ibuprofen and N(G)-nitro-L: -arginine (L-NNA), both alone and in combination, on the responses of regional kidney perfusion to RNS. Under control conditions, RNS produced frequency-dependent reductions in total renal blood flow (RBF; -82+/-3% at 6 Hz), cortical laser-Doppler flux (CLDF; -84+/-4% at 6 Hz) and, to a lesser extent, medullary laser-Doppler flux (MLDF; -46+/-7% at 6 Hz). Ibuprofen did not affect these responses significantly, suggesting that cyclooxygenase products have little net role in modulating renal vascular responses to RNS. L-NNA enhanced RBF (P=0.002), CLDF (P=0.03) and MLDF (P=0.03) responses to RNS. As we have shown previously, this effect of L-NNA was particularly prominent for MLDF at RNS frequencies < or = 1.5 Hz. Subsequent administration of ibuprofen, in L-NNA-pretreated rabbits, did not affect responses to RNS significantly. We conclude that counter-regulatory actions of NO, but not of prostaglandins, partly underlie the relative insensitivity of medullary perfusion to renal nerve activation.
Rajapakse
Niwanthi W
NW
Department of Physiology, Monash University, PO Box 13F, VIC 3800, Clayton, Australia.
Flower
Rebecca L
RL
Eppel
Gabriela A
GA
Denton
Kate M
KM
Malpas
Simon C
SC
Evans
Roger G
RG
D000818:Animals; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007052:Ibuprofen / Q000494:pharmacology; D007668:Kidney / Q000098:blood supply / Q000294:innervation / Q000502:physiology*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology; D011453:Prostaglandins / Q000378:metabolism*; D011817:Rabbits; D012079:Renal Circulation / Q000187:drug effects / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D011453:Prostaglandins; D019335:Nitroarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D007052:Ibuprofen