Endothelium-dependent potentiation by cocaine of serotonin-induced contractions in sheep fetal umbilical artery.
OBJECTIVE
To evaluate the potential role of the endothelium in cocaine-mediated potentiation of serotonin-induced contractions of fetal ovine umbilical artery.


METHODS
Umbilical cords were isolated from near-term pregnant ewes (approximately 140 days). Serotonin-induced--dose-dependent contraction of the umbilical arteries was performed in the presence and absence of 3 mumol/L cocaine. The responses were compared before and after removal of the endothelium.


RESULTS
Cocaine (3 mumol/L) potentiated serotonin-induced contractions in the endothelium-intact ovine fetal umbilical arteries and shifted the concentration-response curve to the left (median effective concentration: 2.69 +/- 0.11 --> 1.23 +/- 0.14 mumol/L, P < .01). The maximum response expressed as a percentage of maximum KCl was also significantly increased (167.4 +/- 12.8 --> 216.2 +/- 16.7, P < .05). Removal of the endothelium abolished the potentiation by cocaine of serotonin-induced contractions (median effective concentration: 1.35 +/- 0.12 --> 1.51 +/- 0.21 mumol/L, P > .05). The maximum responses were also the same (201.8 +/- 14.3 --> 206.4 +/- 16.5).


CONCLUSIONS
The result suggest that, in ovine fetal umbilical arteries, cocaine-mediated potentiation of serotonin-induced contractions is endothelium dependent.
Zhang
L
L
Department of Pharmacology, Loma Linda University School of Medicine, California 92350, USA. lzhang@ccmail.llu.edu
Hu
X Q
XQ
D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D004357:Drug Synergism; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D005333:Fetus / Q000098:blood supply*; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D011247:Pregnancy; D012701:Serotonin / Q000494:pharmacology*; D012756:Sheep; D014469:Umbilical Arteries / Q000502:physiology*
D012701:Serotonin; D003042:Cocaine