Postnatal changes in gut hemodynamics: a possible role for substance P

Area of Science:

• Physiology
• Neonatal Medicine
• Vascular Biology

Background:

• Postnatal intestinal development involves complex hemodynamic and oxygenation regulation.
• The role of neuropeptides like substance P (SP) in the neonatal gut circulation is not fully understood.

Purpose of the Study:

• To investigate the role of substance P (SP) in regulating postnatal intestinal hemodynamics and oxygenation in young swine.

Main Methods:

• Assessed SP levels in swine intestine with age.
• Utilized myography to test SP-induced mesenteric artery relaxation, assessing the role of endothelium and NK-1 receptors.
• Administered exogenous SP and NK-1 receptor antagonist (NATB) in vivo and in vitro to evaluate effects on intestinal vascular resistance and oxygen uptake.

Main Results:

• SP levels decreased with age in swine intestine.
• SP induced endothelium-dependent relaxation of mesenteric arteries via NK-1 receptors and nitric oxide synthase (NOS).
• Exogenous SP reduced intestinal vascular resistance and increased oxygen uptake; NK-1 receptor blockade had a greater effect in younger animals.

Conclusions:

• Substance P plays a significant role in regulating the newborn intestinal circulation.
• SP's influence on gut hemodynamics is particularly crucial in the early postnatal period.
• The NK-1 receptor and nitric oxide pathways are key mediators of SP's vascular effects in the neonatal gut.