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Updated: Aug 15, 2026
Expression of Transgenes in Native Bladder Urothelium Using Adenovirus-Mediated Transduction
Published on: October 6, 2022
Absence of force suppression in rabbit bladder correlates with low expression of heat shock protein 20
Timothy W Batts1, John S Walker, Richard A Murphy
1Cardiovascular Division, Department of Internal Medicine, University of Virginia, Charlottesville, Virginia 22908, USA. TB3B@virginia.edu
Background:
Nitroglycerin can induce relaxation of swine carotid artery without sustained reductions in [Ca2+]i or myosin regulatory light chain (MRLC) phosphorylation. This has been termed force suppression and been found to correlate with ser16-phosphorylation of heat shock protein 20 (HSP20). We tested for the existence of this mechanism in a smooth muscle that is not responsive to nitric oxide.
Methods:
Isometrically mounted mucosa free rabbit bladder strips were contracted with carbachol and relaxed with 8-Br-cGMP, forskolin, or isoprenaline.
Results:
Contraction was associated with a highly cooperative relation between MRLC phosphorylation and force such that very small increases in MRLC phosphorylation induced large increases in force. Relaxation induced by 8-Br-cGMP, forskolin, or isoprenaline did not shift the MRLC phosphorylation-force relation from that observed with carbachol alone, i.e. there was no force suppression. HSP20 content was negligible (approximately two hundred-fold less than swine carotid).
Conclusion:
The lack of force suppression in the absence of HSP20 is consistent with the hypothesized role for HSP20 in the force suppression observed in tonic smooth muscles.
