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ENDOTHELIUM‐DEPENDENT AND‐INDEPENDENT RELAXATION BY DOPAMINE IN THE RABBIT PULMONARY ARTERY
Author(s) -
Yamauchi Masanobu,
Kobayashi Yuta,
Shimoura Keiko,
Hattori Keisuke,
Nakase Akira
Publication year - 1992
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1992.tb00482.x
Subject(s) - endothelium , chemistry , endocrinology , endothelium derived relaxing factor , medicine , agonist , fluphenazine , receptor , haloperidol , dopamine
SUMMARY 1. The relaxing response of dopamine (DA) was studied in the rabbit pulmonary artery. DA caused concentration‐related relaxation in helically cut strips of the artery contracted with prostaglandin F 2α in the presence of prazosin. 2. The DA‐induced relaxation in endothelium‐denuded strips was reduced to about 40% compared with that in endothelium‐intact strips. 3. Methylene blue and haemoglobin, inhibitors of endothelium‐dependent relaxation, reduced the DA‐induced relaxations in endothelium‐intact strips to the level of endothelium‐denuded strips. These results indicate that the DA‐induced relaxation is partially mediated or modified by the release of endothelium‐derived relaxing factor (EDRF). 4. Apomorphine, as a DA agonist, caused concentration‐dependent relaxation in endothelium‐intact strips. Bromocriptine, a DA2 agonist, produced only a little relaxation at higher concentration. 5. In endothelium‐intact strips, haloperidol, a DA antagonist, and the DA 1 antagonists, fluphenazine and SCH 23390 inhibited DA‐induced relaxations. On the other hand spiperone and domperidone, DA2 antagonists, were inactive. 6. In endothelium‐denuded strips, fluphenazine and SCH 23390 inhibited DA‐induced relaxations, but domperidone was inactive. 7. These results indicate that the DA‐induced relaxation is mediated by DA receptors, and that DA 1 receptors are involved in both endothelium‐dependent and‐independent relaxation in the rabbit pulmonary artery.