Circulatory effects of splanchnic nerve stimulation in developing swine

Area of Science:

• Physiology
• Neonatal Physiology
• Vascular Physiology

Background:

• The intestinal circulation's response to sympathetic nerve stimulation is crucial for maintaining homeostasis.
• Understanding the maturity of these responses in neonates is vital for clinical care.

Purpose of the Study:

• To assess the functional maturity of immediate intestinal circulatory responses to efferent splanchnic nerve stimulation in piglets.
• To investigate the role of alpha-adrenergic mechanisms in neonatal intestinal vasoconstriction.

Main Methods:

• Utilized 34 piglets (1 day-1 month old) under pentobarbital anesthesia.
• Measured aortic pressure, heart rate, and superior mesenteric arterial flow.
• Calculated intestinal vascular resistance and stimulated the splanchnic nerve at varying frequencies (2-3 Hz).

Main Results:

• Splanchnic nerve stimulation increased mesenteric resistance, with shorter latency and greater pressor response at higher frequencies (3 Hz).
• Alpha-adrenergic blockade with phentolamine attenuated the vasoconstrictor effect.
• Sympathetic vasoconstrictor tone was present at birth, indicating functional, albeit immature, alpha-adrenergic mechanisms.

Conclusions:

• Alpha-adrenergic mechanisms are functional in the neonatal swine intestinal circulation.
• Sympathetic vasoconstrictor tone is established at birth, contributing to intestinal vascular resistance regulation.