Developmental changes in mesenteric artery reactivity in embryonic and newly hatched chicks

Area of Science:

• Cardiovascular Physiology
• Developmental Biology
• Gastrointestinal Physiology

Background:

• Intestinal nutrient absorption increases dramatically at birth, requiring enhanced blood flow.
• Mammalian vascular adaptations during this transition are partially understood.
• Chick mesenteric arteries (MA) offer a model to study perinatal vascular development.

Purpose of the Study:

• To investigate developmental changes in chick mesenteric artery (MA) reactivity.
• To characterize alterations in vasoconstriction and vasodilation during embryonic and early post-hatch periods.
• To understand the balance between vascular constrictors and dilators in perinatal intestinal adaptation.

Main Methods:

• Wire myography was used to assess MA reactivity in chicken embryos (E15, E19) and newly hatched chicks (NH3h, NH1d).
• Vascular responses to vasoconstrictors (KCl, norepinephrine, U46619, endothelin-1) and vasodilators (acetylcholine, sodium nitroprusside, forskolin) were measured.
• Developmental trajectories of contractile and relaxant efficacies were analyzed.

Main Results:

• MA contractile responses to KCl, norepinephrine, U46619, and endothelin-1 showed distinct developmental patterns.
• KCl-induced contraction increased linearly from E15 to NH1d.
• Norepinephrine and U46619 efficacy increased in ovo but plateaued post-hatch; endothelin-1 efficacy peaked at E19.
• Endothelium-dependent and independent vasodilation remained largely unchanged throughout development.

Conclusions:

• Chick MA constrictive capacity increases during embryonic development, with minimal changes post-hatching.
• Maturation of vasodilator mechanisms precedes that of vasoconstrictor mechanisms.
• Imbalances between vasoconstrictors and vasodilators may contribute to perinatal intestinal diseases.