Antinociceptive effects of Ca2+ channel blockers.
The antinociceptive action of four Ca2+ channel blockers, nifedipine, nimodipine, verapamil and diltiazem, was evaluated and compared to that of morphine using three algesiometric tests in mice and rats, namely, formalin, writhing and modified hot-plate test. Dose-response curves for all the drugs tested were similar and a significant dose-dependent antinociceptive action was evident in the formalin and writhing tests. However, in the hot-plate test, only nimodipine exhibited a significant analgesic effect, confirming the misleading results previously reported for this test. The findings suggest a pharmacological role of Ca2+ channel blockers in the modulation of antinociception under acute conditions. The analgesic action of Ca2+ channel blockers could be mediated by an increase in the nociceptive threshold resulting from interference with Ca2+ influx at opioid receptors, because Ca2+ influx is critical for the release of neurotransmitters and other substances implicated in nociception and inflammation. It is suggested that if a substance has a Ca2+ channel blocking effect, it should probably have some antinociceptive properties.
Miranda
H F
HF
Department of Pharmacology, Faculty of Medicine, Universidad de Chile, Santiago.
Bustamante
D
D
Kramer
V
V
Pelissier
T
T
Saavedra
H
H
Paeile
C
C
Fernandez
E
E
Pinardi
G
G
D000700:Analgesics / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D009553:Nimodipine / Q000494:pharmacology; D010147:Pain Measurement; D051381:Rats; D017208:Rats, Wistar; D014700:Verapamil / Q000494:pharmacology
D000700:Analgesics; D002121:Calcium Channel Blockers; D009553:Nimodipine; D009020:Morphine; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine