Regional circulatory responses to intestinal work in developing swine

Area of Science:

• Physiology
• Gastroenterology
• Pediatric Research

Background:

• Understanding circulatory adaptations to enteral nutrition is crucial for neonatal care.
• Swine models offer valuable insights into human infant physiology.
• Limited data exists on circulatory responses to intraduodenal glucose in neonatal swine.

Purpose of the Study:

• To investigate the circulatory effects of intraduodenal glucose infusion in fasted swine across different age groups.
• To assess the impact of glucose on intestinal oxygen consumption and blood flow.
• To evaluate blood flow autoregulation in the intestine, kidney, and hindlimb post-feeding.

Main Methods:

• 29 fasted swine (1 day to 1 month old) were anesthetized.
• Intraduodenal feeding with 2% and 5% glucose was administered.
• Aortic and intestinal venous pressures, and intestinal, renal, and femoral blood flows were continuously monitored.
• Vascular resistances, oxygen content, and oxygen consumption were calculated.
• Blood flow autoregulation was assessed before and after feeding.

Main Results:

• Intraduodenal glucose increased intestinal oxygen consumption and blood flow in all age groups.
• Intestinal blood flow autoregulation was enhanced only in 2-week-old piglets.
• Blood flow was redistributed from the hindlimb to the working intestine across all ages.
• Renal blood flow autoregulation was sustained in 2-week-old and 1-month-old animals, and became significant in 1-week-old animals during intestinal hyperemia.

Conclusions:

• Fundamental mechanisms for blood flow redistribution to the gut are present at birth in swine.
• Maintenance of renal blood flow during intestinal hyperemia is only partially dependent on autoregulation.
• Age-specific differences exist in the autoregulatory response of intestinal blood flow to glucose feeding.