Antinociceptive effect of nifedipine and verapamil tested on rats chronically exposed to nicotine and after its withdrawal.
Antinociceptive effect of nifedipine (15 mg/kg i.p.) and verapamil (10 mg/kg s.c.) was examined in rats chronically exposed to nicotine (6 mg/kg/day via Alzet osmotic pump for 28 days) and after nicotine withdrawal. Sham operated rats served as control for testing DMSO (dimethylsulfoxide, a solvent for nifedipine), nifedipine and verapamil alone. Nociception was measured by the tail-flick technique. Nifedipine, but not verapamil, injected to control rats produced a ceiling tail-flick latency (20 sec) 30 min after the injection, lasting for 10 min. In rats exposed to chronic nicotine for 3 days, nifedipine treatment exhibited ceiling tail-flick latency within 10 min lasting for 80 min. Tested in rats exposed to nicotine for 3 weeks, nifedipine treatment produced this effect 25 min after the injection lasting for 60 min. Nicotine withdrawal abolished this effect. Verapamil did not exhibit any significant changes in tail-flick latencies. These data support our hypothesis that smoking patients treated with nifedipine could be at a potential risk in developing a high pain threshold and missing the first sign of heart attack--a chest pain.
Zbuzek
V K
VK
Department of Anesthesiology, UMD-New Jersey Medical School, Newark 07103-2714, USA.
Cohen
B
B
Wu
W
W
D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D008297:Male; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D009543:Nifedipine / Q000494:pharmacology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014700:Verapamil / Q000494:pharmacology*
D000700:Analgesics; D009538:Nicotine; D014700:Verapamil; D009543:Nifedipine