5-HT1-like receptors requiring functional cyclo-oxygenase and 5-HT2 receptors independent of cyclo-oxygenase mediate contraction of the human umbilical artery.

1. The interactions between 5-hydroxytryptamine (5-HT) and the antagonists ketanserin, methysergide and phentolamine were studied in isolated preparations of human umbilical artery (HUA) at physiological oxygen tension (Po2 approximately 15 mmHg) and at high PO2 (approximately 120 mmHg). 2.

Inhibition of the oxygen-induced contraction of the isolated human umbilical artery by indomethacin, flurbiprofen, aspirin and drugs modifying Ca2+ disposition.

In this study we have quantified the potency of three cyclo-oxygenase inhibitors, indomethacin, flurbiprofen and aspirin to reduce the vasoconstriction of isolated strips of human umbilical artery (HUA) to changing the oxygen-tension (PO2) of the bathing medium. The inhibitory potencies (IC50) of indomethacin and flurbiprofen were similar (IC50 = 2.1 x 10(-9) M and 7.

Comparison of the effects of oxygen, 5-hydroxytryptamine, bradykinin and adrenaline in isolated human umbilical artery smooth muscle.

The actions of 5-HT, bradykinin and adrenaline on the isolated human umbilical artery (HUA) were examined in paired isometric and isotonic preparations and in paired isometric and perfused preparations at both low (approximately 20 mmHg) and high (approximately 120 mmHg) oxygen tensions. The response to each agonist was potentiated by the higher oxygen tension in all test systems. The relative potency of the three agonists studied was similar using each of the experimental techniques.

Contraction of human umbilical artery, but not vein, by oxygen.

The O2 tension of umbilical arterial blood in utero is 15 mmHg. The contractile effect of increasing the O2 tension above this value was studied quantitatively in vitro in preparations of human umbilical artery and vein. The umbilical arterial smooth muscle was contracted in a concentration-related manner by stepped increments in O2 tension.

Characterization of the receptor mediating contraction of human umbilical artery by 5-hydroxytryptamine.

The 5-hydroxytryptamine (5-HT) receptor in human umbilical artery was found to be similar to that in rabbit aorta. The pD2 was 7.45, pA2 for methysergide 8.