Comparison of relaxation responses of detrusor strips from neuropathic and control patients.
OBJECTIVE
To confirm the existence of relaxation responses to electrical-field stimulation in strips of human detrusor, and to compare these responses in strips from control subjects with those in strips from a group of neuropathic patients exhibiting hyperreflexia.


METHODS
Detrusor specimens were obtained at operation from a group of control patients, and from a group of patients with neuropathy (mainly spina bifida) and a history of hyper-reflexia. Muscle strips were prepared from these, mounted in organ baths, and contracted by exposure to a modified Krebs' solution containing 26 mM KCl and atropine. Relaxation responses were induced by an electrical-field stimulation (50 V, 90 microsecond pulses at 2-16 Hz for 10 s).


RESULTS
Of 29 strips, 20 (69%) from control patients showed relaxations, compared with 17 of 28 strips (61%) from neuropathic patients (P > 0.1). The maximum relaxation response in the control strips was 49 +/- 5.6% (mean +/- SEM) of the maximum relaxation induced by isobutyl methylxanthine, compared with 43 +/- 4.8% in the strips from neuropathic patients (P > 0.1). The maximum response occurred at similar frequencies (4 or 8 Hz) in the two groups. The relaxations were reduced by the inhibitor of nitric oxide synthase, N-nitro L-arginine methyl ester (0.1 mM, P < 0.05), but were not affected by guanethidine (50 microM) or tetrodotoxin (0.5 microM).


CONCLUSIONS
These results confirm the existence of field stimulation-induced relaxation in human detrusor, but suggest that hyper-reflexia in the neuropathic bladder cannot be accounted for by any deficiency in this response.
Department of Urology, Cardiff Royal Infirmary, UK.
P
P
Williams
S
S
Datta
K
K
German
T P
TP
Stephenson
J R
JR
Bedwani
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000328:Adult; D000368:Aged; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009126:Muscle Relaxation / Q000502:physiology*; D009130:Muscle, Smooth / Q000503:physiopathology*; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D016135:Spinal Dysraphism / Q000503:physiopathology; D001750:Urinary Bladder, Neurogenic / Q000503:physiopathology*
D009569:Nitric Oxide; D001120:Arginine; D015056:1-Methyl-3-isobutylxanthine; D019331:NG-Nitroarginine Methyl Ester