Development of vasomotor responses in fetal mesenteric arteries

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Item Type:	Article
Title:	Development of vasomotor responses in fetal mesenteric arteries
Creators Name:	Rouwet, E.V., De Mey, J.G.R., Slaaf, D.W., Heineman, E., Ramsay, G. and le Noble, F.A.C.
Abstract:	Changes in mesenteric arterial diameters were studied using intravital microscopy in chick fetuses at days 13 and 17 of incubation, corresponding to 0.6 and 0.8 fetal incubation time, both during 5 min of hypoxia followed by 5 min of reoxygenation and after topical administration of increasing concentrations (10(-6)-10(-2) M) of norepinephrine (NE) and acetylcholine (ACh). Baseline diameters of second-order mesenteric arteries increased from 56 microm at 0.6 incubation to 75 microm at 0.8 incubation. Acute hypoxia induced a reduction in arterial diameter to 87 +/- 4.4% of baseline at 0.6 incubation and to 44 +/- 6.7% at 0.8 incubation (P < 0.01). During reoxygenation, mesenteric arteries dilated to 118 +/- 6.5% and 121 +/- 7.5% of baseline at 0.6 and 0.8 fetal incubation time, respectively. Phentolamine did not affect the vasoconstriction during hypoxia at 0.6 incubation, whereas this alpha-adrenergic antagonist significantly attenuated the vasoconstrictor response at 0.8 incubation (to 93 +/- 2.7% of baseline, P < 0.01). Topical NE induced maximal vasoconstriction to 71 +/- 3% of baseline at 0.6 incubation and to 35 +/- 3.8% at 0.8 incubation (P < 0.01). Maximal vasodilation to topical ACh was 113 +/- 4.4% and 122 +/- 4.8% of baseline at 0.6 and 0.8 incubation, respectively. These in vivo findings show that fetal mesenteric arteries constrict in response to acute hypoxia and that the increase in magnitude of this vasoconstrictor response from 0.6 to 0.8 of fetal development results from an increase in adrenergic constrictor capacity.
Keywords:	Cardiovascular Development, Hypoxia, Necrotizing Enterocolitis, Norepinephrine, Acetylcholine, Animals, Chickens
Source:	American Journal of Physiology Heart and Circulatory Physiology
ISSN:	0363-6135
Publisher:	American Physiological Society
Volume:	279
Number:	3
Page Range:	H1097-H1105
Date:	September 2000
Official Publication:	http://ajpheart.physiology.org/cgi/content/abstract/279/3/H1097
PubMed:	View item in PubMed

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