Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 52, Issue 2 M94-M96, Copyright © 1997 by The Gerontological Society of America

JOURNAL ARTICLE

The influence of age on isometric and isotonic rat detrusor contractions

PK Lieu, A Sa'adu, EO Orugun and JG Malone-Lee
Centre for Geriatric Medicine, University College London Medical School.

BACKGROUND: Reductions in detrusor shortening velocity and detrusor contractility have been observed in association with aging. The reasons for these changes are unclear. METHODS: We examined the isometric and isotonic responses of detrusor, taken from the bladder body, to adenosine 5'-triphosphate (ATP), noradrenaline (NA), serotonin, and acetylcholine (Ach) in vitro, using bladders from young (30 days) and old (365 days) Sprague-Dawley rats, to determine whether there were any significant age-related differences. RESULTS: Isometric contractions with ATP at doses of 10(-3) to 10(-2) molar concentrations produced greater contractile forces in old rats when compared to young rats (p = .0136 at 10(-2) mole of ATP). Isotonic contractions at similar concentrations also produced significant differences between the young and the old rats, the latter being faster (p = .0225). Isometric contraction with noradrenaline produced significant differences between young and old rats, the latter being stronger. This became apparent at 10(-4) molar concentration of noradrenaline (p = .0043). Isometric contractions with serotonin also produced significantly greater contractions in the old rats when compared to young rats. The differences became apparent at 10(-4) molar concentration of serotonin (p = .045). There were no age-related differences in isotonic and isometric contractile responses to acetylcholine in the doses used in our experimental setup. CONCLUSIONS: Age-related differences in isometric function were detected in response to ATP, NA, and serotonin. Differences in isotonic function were only found in response to ATP and Ach.