Intestinal secretion after jejunal bypass in the ground squirrel

Area of Science:

• Physiology
• Gastroenterology
• Comparative Physiology

Background:

• Previous research indicated fasting and hibernation enhance jejunal chloride secretion in ground squirrels.
• The role of luminal contents in regulating intestinal secretory capacity remained unclear.

Purpose of the Study:

• To investigate the impact of jejunal bypass on intestinal secretory capacity in active (ACT) and hibernating (HIB) ground squirrels.
• To determine if luminal contents directly influence jejunal secretory function.

Main Methods:

• Jejunal segments were subjected to bypass or sham procedures in ACT and HIB squirrels.
• Measurements included mucosal wet weights, tissue conductances, and short-circuit current (Isc) responses.
• Secretory responses were analyzed following electrical stimulation, carbachol, and alanine exposure.

Main Results:

• Jejunal segments with reduced luminal exposure (bypassed or from HIB squirrels) showed decreased mucosal wet weights.
• Segments lacking luminal contact exhibited greater tissue conductances and enhanced secretory responses (Isc) to neural and carbachol stimulation.
• Electrogenic sodium absorption (Isc response to alanine) was highest in segments with minimal luminal exposure.

Conclusions:

• Luminal contents play a direct role in modulating jejunal secretory capacity.
• Both fasting/hibernation and the absence of luminal contents can enhance intestinal secretory responses.