Pb. Patra et Dp. Westfall, POTENTIATION OF PURINERGIC NEUROTRANSMISSION IN GUINEA-PIG URINARY-BLADDER BY HISTAMINE, The Journal of urology, 151(3), 1994, pp. 787-790
Patients suffering from the inflammatory condition of interstitial cys
titis frequently exhibit an increased number of mast cells in the blad
der. To determine whether mast cell mediators have the potential to in
fluence the neurogenic contraction of the bladder smooth muscle and th
ereby possibly contribute to the symptoms of interstitial cystitis, we
examined the effects of histamine, a major inflammatory mediator of m
ast cell origin, on nerve- and agonist-induced contractions of in vitr
o strips of guinea pig urinary bladder. Histamine (10 mu M.) potentiat
ed by more than 50% the nerve-induced contraction of bladder strips ev
oked by field stimulation with 0.5 msec. pulses at 4 Hz. Because the n
eurogenic contraction of the bladder is mediated by at least two neuro
transmitters, acetylcholine (ACh) and ATP, we examined the effects of
histamine on each of these transmitters. Histamine potentiated respons
es to the purinergic component of the neurogenic response (that part o
f the neurogenic response that remains after treatment with atropine)
and potentiated responses to exogenously applied ATP. Histamine did no
t potentiate the response to the cholinergic component of the neurogen
ic response (that part of the neurogenic response that remains after d
esensitization of purinoceptors with alpha, beta-methylene ATP) nor re
sponses to carbachol, a cholinergic agonist. These results indicate th
at histamine potentiates the neurogenic response of the bladder by inf
luencing the purinergic component, apparently at postjunctional sites.