Contractile function of the mechanically lengthened intestine.
BACKGROUND
The application of longitudinal mechanical force induces lengthening of the small intestine. The purpose of this study is to evaluate the contractile function of the mechanically lengthened jejunum in a rodent model.


METHODS
Three groups of rats including normal jejunum, isolated jejunal segment without mechanical lengthening, and isolated lengthened jejunal segment, were studied for contractile function. The isometric contractions of jejunal segments were investigated in organ baths for spontaneous activity and response to potassium chloride and cholinergic carbachol.


RESULTS
The normal control group showed a basal spontaneous activity with an average frequency of 33 +/- 0.68 contractions per min (cpm). The basal spontaneous activity for the isolated group had an average frequency of 26 +/- 2.7 cpm and for the lengthened group had an average frequency of 24 +/- 5.7 cpm. Although the normal control group had a higher frequency of basal spontaneous activity as compared to either the isolated or lengthened groups, there was no statistically significant difference between the frequencies in the isolated and the lengthened groups. All three groups demonstrated a sustained increase in tension upon administration of either potassium chloride or carbachol.


CONCLUSIONS
The response to pharmacological stimulation, as measured by total area under the tension curve and maximal change in basal tone, was larger in the normal group than in the isolated groups. The addition of longitudinal mechanical force to lengthen the isolated jejunal segment did not further alter this change.
Mendoza
Julianne
J
Division of Pediatric Surgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
Chang
Chia-yu
CY
Blalock
Carrie L
CL
Atkinson
James B
JB
Wu
Benjamin M
BM
Dunn
James C Y
JC
D000818:Animals; D019540:Area Under Curve; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D005260:Female; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology*; D007583:Jejunum / Q000033:anatomy & histology / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D009929:Organ Size; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical
D018679:Cholinergic Agonists; D011189:Potassium Chloride; D002217:Carbachol