The action of 5-hydroxytryptamine and some of its antagonists on the umbilical vessels of the human placenta.
The vasoconstrictor action of 5-hydroxytryptamine (5-HT) in the human placental preparation is about 10 times stronger than that of adrenaline and is antagonized by anti-adrenaline compounds like phentolamine. Both 5-HT and adrenaline are antagonized by yohimbine and chlorpromazine. Specific and strong anti-5-HT action is demonstrated for lysergic acid diethylamide (LSD) and tryptamine. Both LSD and tryptamine in larger doses have a vasoconstrictor action. Mescaline has no certain modifying effect on the action of 5-HT, but itself causes vasoconstriction in large doses. The antihistamine drug phenbenzamine in histamine blocking doses abolishes the action of 5-HT in half the preparations tested. The ganglionic blocking agent trimetaphan in large doses antagonizes the action of 5-HT added subsequently, and also, to a lesser degree, the effect of adrenaline. Hexamethonium and tetraethylammonium bromides are ineffective in this preparation. No certain modifying action of reserpine on subsequently added 5-HT could be demonstrated, and the same was true for heparin even in very high concentrations.
D000959:Antihypertensive Agents; D003533:Cyproheptadine; D004837:Epinephrine; D006632:Histamine; D008238:Lysergic Acid Diethylamide; D010646:Phentolamine; D010920:Placenta; D011247:Pregnancy; D012110:Reserpine; D012701:Serotonin; D018490:Serotonin Agents; D012702:Serotonin Antagonists; D014363:Tryptamines; D014470:Umbilical Cord; D014661:Vasoconstriction
D000959:Antihypertensive Agents; D018490:Serotonin Agents; D012702:Serotonin Antagonists; D014363:Tryptamines; D003533:Cyproheptadine; D012701:Serotonin; C030820:tryptamine; D006632:Histamine; D012110:Reserpine; D008238:Lysergic Acid Diethylamide; D004837:Epinephrine; D010646:Phentolamine
SEROTONIN/antagonists; SEROTONIN/effects; UMBILICAL CORD