Gastric acid response to acute exposure to hypergravity

Area of Science:

• Physiology
• Gastroenterology
• Aerospace Medicine

Background:

• Environmental stressors, including hypergravity, are increasingly recognized for their role in gastrointestinal disease pathogenesis.
• While hypergravity's effects on cardiovascular and cerebral functions are well-studied, its impact on the gastrointestinal tract remains largely unexplored.
• Pilot exposure to rapid-onset, sustained hypergravity induces significant physical stress, necessitating an understanding of its gastrointestinal consequences.

Purpose of the Study:

• To investigate the effects of acute hypergravity exposure on gastric secretory activity and gastrin release in a rat model.
• To quantify changes in gastric juice volume and acidity following hypergravity exposure.
• To assess the correlation between hypergravity exposure and plasma gastrin levels.

Main Methods:

• Male Sprague-Dawley rats were subjected to acute +10Gz hypergravity exposure (3 minutes, 3 repetitions).
• Gastric juice and blood samples were collected post-exposure for analysis.
• Gastric juice volume, total acidity, and plasma gastrin levels were measured and compared to a control group.

Main Results:

• Acute +10Gz exposure significantly decreased both gastric juice volume (3.54 ± 0.32 mL/100 g vs. 4.62 ± 0.39 mL/100 g) and total acidity (84.90 ± 5.17 mEq/L vs. 97.37 ± 5.42 mEq/L) compared to controls (P < 0.001 for both).
• Plasma gastrin levels showed no significant alteration after hypergravity exposure.
• These findings indicate a direct inhibitory effect of acute hypergravity on gastric secretion.

Conclusions:

• Acute exposure to +10Gz significantly reduces gastric juice volume and acidity in rats.
• Hypergravity exposure does not appear to significantly alter plasma gastrin levels.
• This study highlights a specific impact of acute hypergravity on gastric physiological functions, distinct from hormonal regulation by gastrin.