| Abstract: | Isolated perfused segments of the ventral rat tail artery have been used in this study to investigate the effects of octapressin on vascular smooth muscle and its interaction with other vasoconstrictor agents. It was found that repeated octapressin administration was associated with tachyphylaxis and that the onset and rate of development of this phenomenon could be modified by cocaine. The constrictor action of catecholamines, electrical stimulation and serotonin on the rat tail artery was potentiated by octapressin. Mechanisms which may be involved in octapressin tachyphylaxis are discussed. |
