[Nicorandil, as ATP-sensitive K+ channel opener, potentiated morphine analgesia].
Recent reports demonstrated that K+ channels could contribute to signal transmission in the brain and spinal cord, and opioids' action may be related to K+ channels' functions. We investigated the antinociceptive effect of epidurally injected ATP-sensitive K+ channel opener, nicorandil, using tail flick test in rats. Epidural nicorandil (100 micrograms.rat-1) increased % maximum possible effect (%MPE) of epidural morphine (1, 10 micrograms.rat-1) from -3% to 40% (P < 0.05) and 46% to 65%, respectively. Epidural glibenclamide (10 micrograms.rat-1), ATP-sensitive K+ channel blocker, antagonized this effect. Epidural nicorandil alone (10 approximately 100 micrograms.rat-1) showed no antinociceptive effects. Systemic nicorandil (100 micrograms.rat-1, i.m.) did not increase the epidural morphine analgesia. These data suggest that the K+ channel opener could point the way to a new approach to pain treatment.
Asano
T
T
Department of Anesthesiology and Critical Care Medicine, Gifu University School of Medicine.
Iida
H
H
Dohi
S
S
Masue
T
T
Shimonaka
H
H
D000255:Adenosine Triphosphate / Q000502:physiology*; D000698:Analgesia; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D004357:Drug Synergism; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D020108:Nicorandil; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000701:Analgesics, Opioid; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D009536:Niacinamide; D020108:Nicorandil; D009020:Morphine; D000255:Adenosine Triphosphate