Effects of sympathetic nerve blockade on vasoconstrictive properties of nitric oxide synthase inhibition in sheep.
OBJECTIVE
Inhibition of nitric oxide synthase causes intense vasoconstriction. This effect is thought to be dependent on sympathetic nerve activity. Thus, we investigated the vasoconstrictive effects of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in sheep, in which a reversible sympathetic block was established by thoracic epidural anesthesia.


METHODS
Sheep (n = 11) were surgically prepared for chronic study. After at least 5 days of recovery, L-NAME was continuously administered and hemodynamics were monitored. This was done in sheep with and without sympathetic blockade in randomized order.


RESULTS
The vasoconstrictive effects of L-NAME were similar in sheep with and without sympathetic blockade.


CONCLUSIONS
The obtained results suggest that the vasoconstrictive properties of nitric oxide synthase inhibitors are independent of sympathetic tone.
Booke
M
M
Department of Anesthesiology and Intensive Care Medicine, University of Münster, Germany.
Waurick
R
R
Van Aken
H
H
Bone
H G
HG
Meissner
A
A
Prien
T
T
Meyer
J
J
D000767:Anesthesia, Epidural; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009407:Nerve Block; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D011897:Random Allocation; D012756:Sheep; D013564:Sympathetic Nervous System / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects*
D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester