Human Urinary Bladder Strip Relaxation by the β-Adrenoceptor Agonist Isoprenaline: Methodological Considerations and Effects of Gender and Age

Departments of Urology and Medicine, University of Duisburg-Essen Essen, Germany.
Frontiers in Pharmacology (Impact Factor: 3.8). 02/2011; 2:11. DOI: 10.3389/fphar.2011.00011
Source: PubMed

ABSTRACT

The present study was primarily designed to explore various methodological aspects related to organ bath experiments evaluating human detrusor relaxation by the β-adrenoceptor agonist isoprenaline. Data are based upon a series of 30 consecutive patients, and this cohort was also used to explore possible effects of gender and age. KCl-induced contraction was related to strip length but not weight or cross-sectional area, indicating that the former is most suitable for data normalization. Storage of detrusor strips in cold buffer for up to 2 days did not affect contractile responses to KCl or efficacy of isoprenaline to cause relaxation but significantly affected the isoprenaline potency. No such alterations were observed with up to 1 day of cold storage. The type (KCl vs. passive tension) or strength of contractile stimulus had only minor effects on isoprenaline responses although these differences reached statistical significance in some cases. Similarly, gender and age had only minor if any effects on KCl-induced contraction or isoprenaline-induced relaxation, but the current data are too limited for robust conclusions. In summary we have evaluated experimental conditions for the testing of human detrusor strip contraction and relaxation which should be useful for future larger studies.

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    • "For example, in an assay using membranes from CHO cells expressing human ␤ 3 -adrenoceptors, isoproterenol stimulated adenylyl cyclase activity with an approximate EC 50 of 250 nM [16]. Schneider and colleagues [17] reported pEC 50 values of approximately 6.8 for isoproterenol in human bladder tissue obtained from different types of patients (age and gender) and treated under a number of different experimental paradigms (KCl versus passive tension and length of time of testing after surgery). The selective ␤ 3 -adrenoceptor antagonist L-748,337 produced concentrationdependent shifts in the isoproterenol concentration–responses curves with a pK B value of 7.34, a value similar to that reported (pK B of 7.65) by Wuest et al. [9] which was determined using human bladder precontracted with carbachol. "
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