Comparison of 5-hydroxytryptamine-induced contraction of rat pulmonary artery to that of aorta in vitro.
We investigated the nature of the contraction produced by 5-hydroxytryptamine (5-HT) in the rat pulmonary artery, and compared it with that produced in the rat aorta. Both ketanserin and ritanserin inhibited 5-HT-induced contraction in the pulmonary artery non-competitively. In contrast, ketanserin competitively antagonized the contraction in the aorta. Bunazosin, a selective alpha 1-blocker, partially inhibited 5-HT-induced contraction in the pulmonary artery, but not in the aorta. In both the pulmonary artery and aorta, 8-OH-DPAT, a 5-HT1A selective agonist, produced a concentration-dependent contraction. In the pulmonary artery, 5-HT and 8-OH-DPAT produced contractions with similar potencies. In contrast, 8-OH-DPAT was less potent than 5-HT in the aorta. Bunazosin inhibited 8-OH-DPAT-induced contraction in both vessels. However, pindolol, a 5-HT1A antagonist, did not inhibit 8-OH-DPAT-induced contraction in the pulmonary artery. These results suggest that 5-HT produces contraction via not only 5-HT2 receptor, but also non-5-HT2 receptor (probably alpha 1-adrenoceptor) in the rat pulmonary artery. Furthermore, 8-OH-DPAT does not activate the 5-HT1A receptor to produce a contraction, but does activate other receptors which interact with alpha 1-adrenoceptor.
Ogawa
Y
Y
First Department of Internal Medicine, Asahikawa Medical College Nishikagura, Japan.
Takenaka
T
T
Onodera
S
S
Tobise
K
K
Takeda
A
A
Hirayama
T
T
Morita
K
K
Kikuchi
K
K
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D010869:Pindolol / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D011799:Quinazolines / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000378:metabolism; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism; D016713:Ritanserin / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D011799:Quinazolines; D018340:Receptors, Adrenergic, alpha-1; D011985:Receptors, Serotonin; D016713:Ritanserin; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D007650:Ketanserin; C018176:bunazosin; D010869:Pindolol