Effect of thromboxane synthetase inhibitors on yohimbine-induced norepinephrine release in the circulation.
The role of thromboxane on norepinephrine release mediated by the presynaptic alphareceptor is studied in conscious rabbits. Intravenous administration of yohimbine, a preferential alpha-2 receptor antagonist increases mean arterial pressure (MBP) by 10 to 15%; the plasma norepinephrine concentration by 71 to 125%. OKY-046, a specific thromboxane synthetase inhibitor, fail to affect the baseline levels as well as yohimbine-induced increases in the MBP and plasma norepinephrine. Yohimbine administration increased plasma renin activity by 27 to 41% which are not affected by OKY administration. These results indicate that the thromboxane system does not affect the norepinephrine release from the nerve terminals by the presynaptic receptor-mediated mechanism. The effect of thromboxane on the renin release is minor and the thromboxane system per se may not play an important role for the renal renin regulation.
Takeda
Y
Y
Second Department of Internal Medicine, School of Medicine, Kanazawa University, Japan.
Miyamori
I
I
Yasuhara
S
S
Takada
R
R
D000179:Acrylates / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007262:Infusions, Intravenous; D008297:Male; D008689:Methacrylates / Q000494:pharmacology*; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood* / Q000378:metabolism; D011817:Rabbits; D013268:Stimulation, Chemical; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism*; D015016:Yohimbine / Q000008:administration & dosage / Q000494:pharmacology*
D000179:Acrylates; D008689:Methacrylates; D015016:Yohimbine; C034364:ozagrel; D009638:Norepinephrine