Key result
Cooling increased and warming decreased the sensitivity of 5-HT- and ACh-induced contractions in human umbilical vessels, effects that were independent of nitric oxide.
Cooling and warming alter the sensitivity of human umbilical vessels to contractile agents independently of nitric oxide.
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Temperature effects on umbilical vessel reactivity warrant lab standardization; leaves open in vivo fetal hemodynamic relevance.
The effects of cooling (to 28 degrees C) and warming (to 41 degrees C) on the vasoconstrictions induced by 5-hydroxytryptamine (5-HT) and acetylcholine (ACh) and the role of nitric oxide in these effects were analyzed in human umbilical artery and vein. 5-HT (10(-9)-10(-4) M) and ACh (10(-9)-10(-4) M) induced concentration-dependent contractions at 37, 28 and 41 degrees C. During cooling, the sensitivity, but not the maximal response, of 5-HT and ACh was significantly higher than at 37 degrees C; and during warming, again the sensitivity, but not the maximal response, of both contractile agents was significantly lower than at 37 degrees C. Neither cooling to 28 degrees C nor warming to 41 degrees C, after treatment with N(G)-nitro-L-arginine methyl esther (L-NAME, 10(-4) M), modify the effect of temperature in both vessels. These results suggest that cooling- and warming-induced responses in human umbilical artery and vein are independent of nitric oxide.
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Atalık et al. (2008) studied this question. Cooling (to 28 degrees C) and warming (to 41 degrees C) vs. 37 degrees C was evaluated on Vasoconstrictions induced by 5-HT and ACh and the role of nitric oxide. Cooling increased and warming decreased the sensitivity of 5-HT- and ACh-induced contractions in human umbilical vessels, effects that were independent of nitric oxide.
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