The use of hypochlorous acid as a model for investigating bladder overactivity.

UNLABELLED: Involuntary detrusor contractions play an important role in the development of urge incontinence. Also in an in-vitro situation contractions which develop spontaneously can be seen; a parallel with the in vivo observations is likely. In order to study this muscle overactivity we investigated the possibility to induce this phenomenon with oxidative stress using hypochlorous acid (HOCl). MATERIALS AND METHODS: Urinary bladder muscle strips from pigs were mounted in a custom made organ bath and incubated for 20 minutes in Krebs solution. Next HOCl (10 µM) was added to the organ bath and the onset of overactive contractions was closely followed. Overactivity was defined as a development of more than 5 phasic detrusor contractions per minute without any other provocation in the 30 minutes following addition of HOCl to the organ bath. RESULTS: Of the 50 strips which were used 36 (72%) became overactive after exposure to HOCl during 30 minutes recording. In 76% of the overactive strips overactivity occurred within 5 minutes, in 19% between 5 and 15 minutes, and in 5% it took longer than 15 minutes. The overactivity could be stopped by washing out HOCl for 10 minutes after which still a significant contraction after EFS and ACh stimulation was seen. CONCLUSIONS: It can be concluded that an oxidative stressor, like HOCl, is capable of inducing smooth muscle overactivity. This model can be used for the development and testing of new treatment modalities for the overactive detrusor. Furthermore, this study provides evidence for a causal relationship between oxidative stress and detrusor overactivity.

The use of Hypochlorous Acid as a Model for Investigating Bladder Overactivity

Involuntary detrusor contractions play an important role in the development of urge incontinence. Also in an in-vitro situation contractions which develop spontaneously can be seen; a parallel with the in vivo observations is likely. In order to study this muscle overactivity we investigated the possibility to induce this phenomenon with oxidative stress using hypochlorous acid (HOCl). Materials and Methods Urinary bladder muscle strips from pigs were mounted in a custom made organ bath and incubated for 20 minutes in Krebs solution. Next HOCl (10µM) was added to the organ bath and the onset of overactive contractions was closely followed. Overactivity was defined as a development of more than 5 phasic detrusor contractions per minute without any other provocation in the 30 minutes following addition of HOCl to the organ bath. Results Of the 50 strips which were used 36 (72%) became overactive after exposure to HOCl during 30 minutes recording. In 76% of the overactive strips overactivity occurred within 5 minutes, in 19% between 5 and 15 minutes, and in 5% it took longer than 15 minutes. The overactivity could be stopped by washing out HOCl for 10 minutes after which still a significant contraction after EFS and ACh stimulation was seen. Conclusions It can be concluded that an oxidative stressor, like HOCl, is capable of inducing smooth muscle overactivity. This model can be used for the development and testing of new treatment modalities for the overactive detrusor. Furthermore, this study provides evidence for a causal relationship between oxidative stress and detrusor overactivity. .

The gene for the precursor of plastocyanin from the cyanobacterium Anabaena sp. PCC 7937: isolation, sequence and regulation.

The gene encoding plastocyanin (petE1) from Anabaena sp. PCC 7937 was isolated using two sets of mixed oligonucleotide hybridization probes derived from conserved regions in the protein. Plastocyanin is encoded as a preprotein of 139 amino acids. The amino-terminal extension of 34 residues has all the characteristics of a signal peptide and is probably involved in translocation of preplastocyanin over the thylakoid membrane. The level of the petE1 mRNA, a single transcript of about 740 bases, was found to be severely reduced under conditions of Cu2+ deficiency. The petE1 gene was transferred to the genome of Synechococcus sp. PCC 7942, which did not appear to contain a structural gene for plastocyanin itself. The integrated gene becomes expressed at the transcriptional level, regardless of the amount of Cu2+ available.