Viscoelastic properties of the human colon

• Published in: American journal of physiology: Gastrointestinal and liver physiology 2001-08, Vol.281 (2), p.G459-G466
• Main Authors: Bharucha, A E, Hubmayr, R D, Ferber, I J, Zinsmeister, A R
• Format: Article
• Language: English
• Subjects: Adult; Atropine - pharmacology; Body Mass Index; Colon - drug effects; Colon - physiology; Compliance; Elasticity; Female; Humans; Male; Middle Aged; Pressure; Reproducibility of Results
• ISSN: 0193-1857; 1522-1547
• DOI: 10.1152/ajpgi.2001.281.2.G459

Our objectives were to characterize colonic viscoelastic properties of the human descending colon by assessing pressure-volume (P-V) relationships during barostatic balloon distension. In 16 healthy subjects, a balloon was inflated to 44 mmHg and then deflated to 0 mmHg in 4-mmHg steps at 10, 30, and 60 ml/min, allowing volume fluctuations to stabilize at each pressure increment. Thereafter, these "quasi-static" P-V curves were compared with "dynamic" distensions to 300 ml, at 1 and 10 ml/s, before and after intravenous atropine in another five subjects. During quasi-static curves, balloon volume stabilized at each pressure increment. Quasi-static P-V curves were reproducible within individuals and approximated to a power exponential function and revealed hysteresis, indicative of viscoelasticity. Body mass index influenced quasi-static P-V curves during inflation but not during deflation. The colon was less compliant during dynamic distensions at 10 ml/s than during quasi-static distensions. Atropine increased quasi-static compliance and attenuated differences between quasi-static and rapid distensions. We conclude that colonic viscoelastic properties can be assessed by quasi-static P-V curves. Rapid colonic distension activated neural reflexes, thereby reducing colonic compliance compared with quasi-static distensions.