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Phasic and tonic stress-strain data obtained in intact intestinal segment in vitro
Jingbo Zhao1, Donghua Liao, Hans Gregersen
1Center of Excellence in Visceral Biomechanics and Pain, Aalborg Hospital Science and Innovation Center (AHSIC), Sdr. Skovvej 15, 9000, Aalborg, Denmark. jz@rn.dk
Digestive Diseases and Sciences
|May 8, 2008
Summary
Small intestine mechanics involve muscle contractions. This study found that longitudinal stretching reduces active stress in the jejunum and ileum, with greater reduction in the jejunum.
Area of Science:
- Gastroenterology
- Biomechanics
- Physiology
Background:
- The small intestine's mechanical function relies on smooth muscle contractions, generating phasic and tonic forces.
- Understanding stress-strain relationships in intestinal segments is crucial for comprehending gut motility and mechanics.
Purpose of the Study:
- To quantify phasic and tonic stress-strain curves during distension of isolated rat jejunum and ileum.
- To investigate the influence of longitudinal stretch on intestinal circumferential stress-strain behavior.
Main Methods:
- Isolated rat jejunum and ileum segments were subjected to ramp distension in an organ bath.
- Active and passive stress-strain data were collected at varying longitudinal stretch ratios (0%, 10%, 20%).
- Passive conditions were induced using papaverine, a calcium antagonist.
Main Results:
- Both total and passive circumferential stresses exhibited exponential increases with strain.
- Jejunum displayed higher amplitudes of total and passive stress compared to the ileum.
- Longitudinal stretching decreased total circumferential stress but increased passive stress, leading to reduced active stress, most notably in the jejunum.
Conclusions:
- Circumferential active-passive stress and strain in the small intestine are dependent on longitudinal stretch.
- Significant differences exist in stress-strain responses between the jejunum and ileum under varying stretch conditions.
