Interstitial cells of Cajal in the urethra as effectors of the nitric oxide action through the cyclic GMP pathway

Angeles Garcia-Pascual , Maria Sancho, Gonzalo Costa and Domingo Triguero

Department of Physiology, School of Veterinary Medicine, Complutense University, Madrid, Spain

author email corresponding author email

from 3^rdInternational Conference on cGMP Generators, Effectors and Therapeutic Implications
Dresden, Germany. 15–17 June 2007

BMC Pharmacology 2007, 7(Suppl 1):P23doi:10.1186/1471-2210-7-S1-P23

The electronic version of this abstract is the complete one and can be found online at: http://www.biomedcentral.com/1471-2210/7/S1/P23

Published:

25 July 2007

Background

Specialized cells similar to the interstitial cells of Cajal (ICC) of the gut have been described in the urethra where they seem to act as pacemakers of contractility [1]. Furthermore, nitric oxide (NO) is the main transmitter involved in relaxation of the urethra during micturition [2]. Here we show that urethral ICC are preferential targets of the NO action by the production of cyclic GMP (cGMP) in response to both exogenous addition or endogenous release of NO.

Materials and methods

Under isometric recording of contractile tension, norepinephrine-precontracted preparations from female lambs and rats were subjected to either electrical field stimulation (EFS, 2 Hz for 4 min) or S-nitrocysteine (SNC, 10 mM for 2–10 min) addition, in the continuous presence of cGMP-phosphodiesterase inhibitors. Unstimulated pre-contracted preparations served as controls. Some preparations were pre-treated with the guanilate cyclase inhibitor ODQ (10 mM) for 30 min. Samples were fixed in 4% paraformaldehyde and processed for cGMP immunohistochemistry. Double immunolabelling cGMP-vimentine, cGMP-neuronal NO synthase (nNOS) and cGMP-Protein gene product 9.5 (PGP 9.5, neuronal marker) were also performed.

Results

cGMP-immunoreactivity was intense in dense networks of ICC localized at the serosal, muscular and sub-urothelial layers in sheep and rats preparations exposed to either SNC or EFS (Fig. 1). Reactivity was markedly reduced in control preparations and almost disappeared in ODQ-treated preparations, showing a basal activity stimulated by SNC and EFS. cGMP positive ICC were also vimentine positive. Double labellings cGMP-(nNOS) and cGMP-PGP 9.5 showed no co-localization but close structural relationship between ICC and nerve terminals.

Figure 1. A. cGMP immunoreactive ICC in the smooth muscle layer of the rat urethra exposed to SNC. B. cGMP positive ICC are also reactive to vimentine (red). C. cGMP ICC (green) did not co-localize with nNOS (red) which is present in adjacent intramural nerves in urethra from sheep. Bar = 30 μm.

Conclusion

These findings suggest that ICC may play an intermediary role in the urethral nitrergic neurotransmission, as effectors of the NO action, which in turn would induce muscular relaxation by means of unknown mechanisms.

Acknowledgements

Anti-sheep cGMP antibody was a generous gift of Dr. J. de Vente. This work was supported by Ministerio de Educación y Ciencia (BFU2006-15135-C02-01) of Spain.

References

Sergeant GP, Thornbury KD, McHale NG, Hollywood MA: Interstitial cells of Cajal in the urethra.
J Cell Mol Med 2006, 10:280-291. PubMed Abstract | Publisher Full Text
Garcia-Pascual A, Costa G, Garcia-Sacristan A, Andersson KE: Relaxation of sheep urethral muscle induced by electrical stimulation of nerves: involvement of nitric oxide.
Acta Physiol Scand 1991, 141:531-539. PubMed Abstract

This article is part of the supplement: 3rd International Conference on cGMP Generators, Effectors and Therapeutic Implications