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.
Second Department of Internal Medicine, School of Medicine, Kanazawa University, Japan.
Y
Y
Takeda
I
I
Miyamori
S
S
Yasuhara
R
R
Takada
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