J Korean Med Sci.  2005 Feb;20(1):13-19. 10.3346/jkms.2005.20.1.13.

Chronic Hypoxia Alters Vasoconstrictive Responses of Femoral Artery in the Fetal Sheep

• Kim YH
• Veille JC
• Cho MK
• Kang MS
• Kim CH
• Song TB
• Figueroa J

• KMID: 1781717
• DOI: http://doi.org/10.3346/jkms.2005.20.1.13

Abstract

The purpose of this study was to determine if mild hypoxia alters the responsiveness to vasoactive agents in the renal and the femoral arteries in the fetal sheep. Ten pregnant sheep were operated under halothane anesthesia at 116 to 124 days' gestation. A maternal tracheal catheter was placed for infusing compressed air (control group, n=5) or nitrogen (hypoxia group, n=5) starting on post operative day 6 and maintained for 5 days. Femoral and renal arteries were harvested from the fetus to study the constriction response to phenylephrine (PE 10(-9) to 10(-5) mol/L). To determine the involvement of nitric oxide as a modulator of vessel constriction, N-nitro-Larginine methyl ester (L-NAME) was used at a concentration of 10(-4) mol/L in parallel chambers. In the hypoxia group, maternal Pao2 significantly decreased from a base-line of 110.4 +/-1.4 to 80.5 +/-1.6 (mmHg, p <0.01), fetal Pao2 significantly decreased from a baseline of 20.9 +/-0.3 to 15.5 +/-0.1 (mmHg, p <0.01). Hypoxia was associated with a significant increase in PE maximal response in the absence (184.5 +/-6.6 vs. 146.2 +/-4.3) and presence (166.9 +/-6.3 vs. 145.0 +/-4.5) of L-NAME, and a decrease in EC50 in the absence (6.0 +/-1.1 vs. 27.0 +/-4.1) of L-NAME of femoral arteries. However, there were no significant differences in PE maximal response and EC50 in the absence and presence of L-NAME of renal arteries. We concluded that mild chronic hypoxia seems to increase the fetal femoral artery response to PE, but not in the fetal renal artery. This observation is consistent with a redistribution of cardiac output away from the carcass.

Keyword

Anoxia; Femoral artery; Blood Vessels; Phenylephrine

MeSH Terms

Animals
*Anoxia
Blood Glucose/metabolism
Dose-Response Relationship, Drug
Enzyme Inhibitors/pharmacology
Femoral Artery/*embryology/*pathology
Hematocrit
Hydrogen-Ion Concentration
Kidney/blood supply
Lactates/blood/metabolism
NG-Nitroarginine Methyl Ester/pharmacology
Nitric Oxide/metabolism
Nitric-Oxide Synthase/antagonists & inhibitors
Phenylephrine/chemistry/metabolism/pharmacology
Renal Artery/pathology
Sheep/*embryology
Time Factors
Vasoconstrictor Agents/*pharmacology

Figure

• 

  Fig. 1 Concentration-effect curves for phenylephrine (PE 10-9 to 10-5 mol/L) in isolated fetal sheep renal and femoral arteries obtained from normoxic (control group n=5) and hypoxic fetuses (hypoxia group n=5). Arteries were studied with and without L-NAME in the bath. Results are expressed as a percentage of the maximal response to KCl in each vessel and presented as mean±SEM.

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