Does vasoactive intestinal polypeptide mediate the pathophysiology of bowel obstruction?

Area of Science:

• Gastroenterology
• Endocrinology
• Surgical Pathophysiology

Background:

• Small bowel obstruction (SBO) is a common surgical emergency.
• The role of bioactive peptides in SBO pathophysiology is not well understood.
• Portal circulation may be a key pathway for peptide-mediated effects in SBO.

Purpose of the Study:

• To investigate the release of bioactive peptides into the portal circulation during SBO.
• To determine if these peptides contribute to the pathophysiologic changes associated with SBO.
• To explore the potential role of vasoactive intestinal peptide (VIP) in SBO.

Main Methods:

• A subacute canine small bowel obstruction model was utilized.
• Fifty percent diameter occlusion was employed to induce SBO.
• Portal and systemic plasma levels of VIP, peptide YY, and gastrin were measured via radioimmunoassay at 24-hour intervals over 5 days.
• Control animals underwent sham laparotomy.

Main Results:

• All measured peptides exhibited portal and peripheral gradients in both groups.
• Peptide concentrations remained stable in control dogs postoperatively.
• Obstructed dogs showed a marked increase in portal VIP levels, reaching a median of 95 pmol/liter at 96 hours, compared to 31.5 pmol/liter in controls.
• These elevated portal VIP levels are consistent with known experimental effects of hypersecretion and splanchnic vasodilation.

Conclusions:

• Bioactive peptides, particularly VIP, are released into the portal circulation during small bowel obstruction.
• The release of VIP may mediate local pathophysiologic alterations in SBO.
• Systemic effects observed in SBO could also be explained by the known cardiopulmonary bioactivity of VIP.