Interactions of bradykinin and norepinephrine on rat cutaneous nociceptors in both normal and inflamed conditions in vitro.
Many inflammatory chemical mediators excite or sensitize nociceptors, which had led some researchers to believe that they may interact with each other to maintain a persistent painful state. We examined how the excitatory mediators norepinephrine (NE) and bradykinin (BK) interact, using single fiber recordings from cutaneous nociceptors. We observed that NE augmented the BK-induced response in both control and adjuvant-inflamed rats in a way different from NE-induced excitation in inflamed animals only. BK also tended to augment the NE-induced response (examined only in inflamed rats). Our results provide the first evidence that BK and NE synergistically interact on nociceptors.
Banik
Ratan Kumar
RK
Department of Neural Regulation, Research Institute of Environmental Medicine, Nagoya University, Furo, Chikusa, Nagoya 464-8601, Japan.
Sato
Jun
J
Giron
Rocio
R
Yajima
Hiroki
H
Mizumura
Kazue
K
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005620:Freund's Adjuvant; D066298:In Vitro Techniques; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects* / Q000502:physiology; D009431:Neural Conduction / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew; D012867:Skin / Q000187:drug effects / Q000294:innervation*; D013268:Stimulation, Chemical
D005620:Freund's Adjuvant; D001920:Bradykinin; D009638:Norepinephrine