The antagonism induced by ruthenium red of the actions of capsaicin on the peripheral terminals of sensory neurons: further studies.
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.
Maggi
C A
CA
Pharmacology Department, A. Menarini Pharmaceuticals, Florence, Italy.
Santicioli
P
P
Geppetti
P
P
Parlani
M
M
Astolfi
M
M
Pradelles
P
P
Patacchini
R
R
Meli
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002211:Capsaicin / Q000037:antagonists & inhibitors*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012428:Ruthenium / Q000494:pharmacology*; D012430:Ruthenium Red / Q000494:pharmacology*; D013373:Substance P / Q000378:metabolism; D001743:Urinary Bladder / Q000187:drug effects
D012430:Ruthenium Red; D013373:Substance P; D012428:Ruthenium; D002211:Capsaicin; D002118:Calcium