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Pregnancy-induced changes in ovine cerebral arteries
A D Hull1, D M Long, L D Longo
1Department of Physiology, Loma Linda University School of Medicine, California 92350.
The American Journal of Physiology
|January 1, 1992
Summary
Pregnancy alters sheep cerebral arteries, increasing contractile force and altering endothelial responses. These changes affect arterial composition, stiffness, and reactivity, highlighting pregnancy-specific cerebrovascular effects.
Area of Science:
- Physiology
- Vascular Biology
- Reproductive Science
Background:
- Pregnancy significantly impacts maternal physiology.
- Cerebrovascular adaptations during pregnancy are not fully understood.
- Ovine models offer insights into human pregnancy physiology.
Purpose of the Study:
- To investigate the effects of pregnancy on ovine cerebral vasculature.
- To compare intracranial and extracranial arteries in pregnant and nonpregnant sheep.
- To assess changes in arterial composition, stiffness, contractility, and endothelial function.
Main Methods:
- Isolated endothelium-intact arterial segments from pregnant and nonpregnant sheep.
- Analysis of middle cerebral (MCA), posterior communicating (PC), basilar (BAS), and common carotid (COM) arteries.
- Measurement of water content, protein content, passive stress-strain, contractile responses, and endothelial-dependent/independent relaxations.
Main Results:
- Pregnancy increased vessel water and cellular protein content in most studied arteries.
- Arterial stiffness decreased in the MCA during pregnancy.
- Maximum contractile responses increased in arteries from pregnant ewes.
- Endothelium-independent relaxation (SNAP) increased in the distal MCA.
- Endothelium-dependent relaxation (A23187) decreased in the common carotid artery.
Conclusions:
- Pregnancy induces vessel-specific changes in ovine cerebrovasculature.
- Key alterations include increased contractile force and reduced vascular stiffness.
- Endothelial reactivity is modified, with differential effects on relaxation pathways.
- These findings underscore the complex cerebrovascular adaptations during pregnancy.