Inhibition of the contractile responses of isolated human and rat bladders by clenbuterol.
OBJECTIVE
We investigated the inhibition of the contractile responses of human continent and unstable detrusor muscle by the beta2 agonist clenbuterol as well as the inhibition of electrical field stimulation evoked contractile responses of isolated rat bladder muscle strips by orally administered clenbuterol.


METHODS
The contractile responses of human continent and unstable detrusor muscle strips to electrical field stimulation (0.05 milliseconds, 0.5 to 80 Hz.) were measured before and after adding 10(-9) to 10(-4) M. clenbuterol in vitro. In addition, 6 rats per group were dosed orally with 2 microg x kg(-1) clenbuterol daily acutely (1 dose) or chronically (1 dose daily for 8 days), or with distilled water to serve as controls. The contractile response to electrical field stimulation of strips of isolated detrusor muscle was then measured. Serum clenbuterol levels were analyzed in duplicate by enzyme-linked immunosorbent assay and high performance liquid chromatography.


RESULTS
In vitro clenbuterol significantly inhibited the electrical field stimulation evoked contractile responses of detrusor muscle strips from unstable but not continent human bladders. A significant inhibitory effect of clenbuterol on the electrical field stimulation evoked contractile response of rat detrusor muscle was observed after chronic but not acute oral dosing (p <0.01). Serum clenbuterol levels measured by enzyme-linked immunosorbent assay and high performance liquid chromatography were not significantly different.


CONCLUSIONS
Clenbuterol or related beta2-adrenoceptor agonists may represent a useful therapeutic strategy for detrusor muscle overactivity.
Hudman
D
D
Division of Medicine for the Elderly, University of Leicester, Leicester General Hospital, Leicester, United Kingdom.
Elliott
R A
RA
Whitaker
P
P
Terry
T R
TR
Sandhu
D P
DP
Norman
R I
RI
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000368:Aged; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002976:Clenbuterol / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology
D000318:Adrenergic beta-Agonists; D002976:Clenbuterol