Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Introduction: Urine osmolarities vary widely above and below plasma osmolarity. When the mucosa is inflamed it may leak, exposing the muscle to abnormal osmolarities. This study investigates the effect of hypo-osmolar solutions (HOTs) on human detrusor muscle strips. Materials and methods: With ethical approval, human detrusor muscle removed at surgery was dissected into strips (5 × 1 × 1 mm), mounted in an organ bath and perfused with gassed Tyrode's solution (pH 7.36, 36°C, osmolarity 285 mOsmol/L). Isometric tension was recorded via a microstrain gauge transducer. The solution was made hypo-osmolar by removing NaCl. Gadolinium (Gd3+). a blocker of stretch activated channels (SACs), and Diltiazem. an L-type Ca2+ channel antagonist, were used at 10 μmol/L. The results are expressed as mean (SEM) percentage of maximal tension produced by 1 μmol/L carbachol for each patient. Results: HOTs produced an increase in tension of similar magnitude to 1 μmol/L carbachol. The effect depended on osmolarity rather than ionic strength; a solution of reduced ionic strength made iso-osmolar by mannitol produce no contraction. In paired experiments. Gd3+ and Diltiazem significantly reduced the response to HOTs. with values of 108 (25) and 75 (27) (P = 0.004, n = 11) for Gd3+, and 69 (11) and 37 (9) (P = 0.001, n = 9) for Diltiazem, respectively. In Ca2+-free solution, a response was still present but was significantly reduced, at 65 (10) and 21 (8). respectively (P = 0.001, n = 9), indicating direct mobilization of Ca2+ from intracellular stores. Conclusions: HOTs produced a tension increase in detrusor strips that appears to be dependent partly on the release of intracellular Ca2+ partly on the influx of Ca2+ through L-type Ca2+ channels and partly upon SACs. © 1997 British Journal of Urology.

Type

Journal article

Journal

British Journal of Urology

Publication Date

01/12/1997

Volume

79

Pages

10 - 11