The antagonism induced by ruthenium red of the actions of capsaicin on the peripheral terminals of sensory neurons: further studies |
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Authors: | C A Maggi P Santicioli P Geppetti M Parlani M Astolfi P Pradelles R Patacchini A Meli |
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Institution: | Pharmacology Department, A. Menarini Pharmaceuticals, Florence, Italy. |
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Abstract: | Ruthenium Red, an inorganic dye which blocks transmembrane calcium (Ca) fluxes in neural tissues, reduced the capsaicin-induced release of substance P-like immunoreactivity from muscle strips of the guinea-pig urinary bladder in a concentration-dependent (30 nM - 3 microM) manner, and protected the sensory fibers from capsaicin-induced densensitization. A similar antagonism of the actions of capsaicin was observed in functional experiments (capsaicin-induced contraction of the isolated guinea-pig bladder or inhibition of twitches of the isolated rat vas deferens). In view of its established action on the depolarization-coupled entry of Ca into synaptosomes and the secretion of transmitter, we propose that Ruthenium Red could antagonize the action of capsaicin on the peripheral terminals of sensory nerves by a similar mechanism, thereby suppressing transmitter secretion and preventing the establishment of desensitization. |
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