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Journal of Biomedicine and Biotechnology
Volume 2011, Article ID 489720, 9 pages
Research Article

Phasic and Tonic Smooth Muscle Function of the Partially Obstructed Guinea Pig Intestine

1Mech-Sense, Aalborg Hospital, 9000 Aalborg, Denmark
2Institute of Clinical Medicine, Aarhus University Hospital, 8000 Aarhus, Denmark
3Sino-Danish Center for Education and Research, Aarhus University, 8000 Aarhus, Denmark

Received 28 June 2011; Accepted 29 August 2011

Academic Editor: Henk Granzier

Copyright © 2011 Jingbo Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study was to generate phasic and tonic stress-strain curves for evaluation of smooth muscle function in the obstructed guinea pig jejunum. Partial and sham obstruction of the jejunum in guinea pigs was created surgically, with guinea pigs not being operated on served as normal controls. The animals survived 2, 4, 7, and 14 days, respectively. The jejunal segment was distended to 10 cm H2O. The pressure and outer diameter changes were recorded. Passive conditions were obtained by using papaverine. Total phasic, tonic, and passive circumferential stress and strain were computed from the diameter and pressure data with reference to the zero-stress-state geometry. The active phasic and tonic stresses were defined as the total phasic and tonic stress minus the passive stress. The thickness of intestinal muscle layers increased in a time-dependent manner after obstruction. The amplitude of passive, total phasic, total tonic, active phasic, and active tonic circumferential stresses increased as function of strain 7 days after obstruction. However, when normalized to muscle layer thickness, the amplitude of active stresses did not differ among the groups. In conclusion, the long-term-obstructed intestine exhibits increased total smooth muscle contraction force. However, the contraction force per smooth muscle unit did not increase.