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Open Access Research article

The impact of discrete modes of spinal cord injury on bladder muscle contractility

Abhishek Seth12, Yeun Goo Chung1, Daniel Kim3, Aruna Ramachandran12, Vivian Cristofaro245, Pablo Gomez III12, Duong Tu12, Lin Huang1, Larry I Benowitz23, Dolores Di Vizio126, Maryrose P Sullivan245* and Rosalyn M Adam127*

Author Affiliations

1 Urological Diseases Research Center, Boston Children’s Hospital, Boston, MA, 02115, USA

2 Department of Surgery, Harvard Medical School, Boston, MA, 02115, USA

3 Department of Neurosurgery, Boston Children’s Hospital, Boston, MA, 02115, USA

4 Division of Urology, Veterans Administration Boston Healthcare System, 1400, V F W Parkway, West Roxbury, MA, 02132, USA

5 Department of Surgery, Brigham and Women’s Hospital, Boston, MA, 02115, USA

6 Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA, 90048, USA

7 Enders Research Laboratories, Rm 1061, 300 Longwood Avenue, Boston, MA, 02115, USA

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BMC Urology 2013, 13:24  doi:10.1186/1471-2490-13-24

Published: 13 May 2013

Abstract

Background

Prior studies have compared the effect of spinal cord injury elicited using distinct approaches on motor and visceral function. However, the impact of such discrete modes of injury specifically on bladder muscle contractility has not been explored in detail. The goal of this study is to compare the impact of complete spinal cord transection versus clip compression at thoracic vertebra eight (T8) on bladder muscle contractility.

Methods

Rats underwent no treatment (Control), laminectomy (Sham, SH); complete extradural transection (TX); or cord compression with an aneurysm clip (CX). Bladders and spinal cords were harvested at 6 wk for contractility studies or histological analysis.

Results

Detrusor strips from TX and CX rats showed higher spontaneous activity than those from SH rats. Furthermore, the duration of the neurally-mediated contractile response was longer in TX and CX rats compared to controls and showed attenuated relaxation. No significant differences were observed between muscle strips from SH, TX or CX rats in response to KCl, ATP or phenylephrine. However, tissues from TX and CX rats showed a higher sensitivity to carbachol compared to that from SH animals.

Conclusions

Complete SCI in rats either by cord transection or compression elicits qualitatively similar changes in bladder muscle contractility. Whereas cord transection is arguably easier to perform experimentally, cord compression better models the situation observed clinically, such that each approach has clear advantages and limitations.

Keywords:
Bladder; Smooth muscle; Spinal cord injury; Muscle contractility