Fetal Sheep Mesenteric Resistance Arteries: Functional and Structural Maturation

Area of Science:

• Cardiovascular Physiology
• Developmental Biology
• Vascular Biology

Background:

• Fetal blood pressure rises in late gestation, but the vascular mechanisms are not fully understood.
• Understanding resistance artery maturation is crucial for identifying risks of adult vascular dysfunction.

Purpose of the Study:

• To investigate the functional and structural development of fetal sheep mesenteric resistance arteries.
• To elucidate the mechanisms underlying vascular maturation during late gestation.

Main Methods:

• Wire myography was employed to assess arterial function.
• Immunohistochemistry was used to analyze vascular structure and protein expression.

Main Results:

• Resting wall tension and vasocontraction (potassium, noradrenaline, endothelin-1) increased from 0.7 to 0.9 gestation.
• Endothelium-dependent relaxation to acetylcholine and prostaglandin E2 emerged by 0.9 gestation.
• Vascular responsiveness changes were linked to sympathetic and sensory innervation maturation, not structural media changes or receptor expression.

Conclusions:

• Vascular maturation in late ovine gestation involves increased resting tension and altered vasoconstrictor/vasodilator capacity.
• Maturation of intracellular pathways, rather than structural media changes or receptor upregulation, underlies these vasoactive responses.