RT Journal Article
SR Electronic
T1 Cardiovascular Effects of Nicotine, Chlorisondamine, and Mecamylamine in the Pigeon
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 73
OP 78
DO 10.1124/jpet.103.057307
VO 308
IS 1
A1 Kathryn K. Chadman
A1 James H. Woods
YR 2004
UL http://jpet.aspetjournals.org/content/308/1/73.abstract
AB Chlorisondamine and mecamylamine are nicotinic antagonists that produce both ganglionic and central blockade. Chlorisondamine, when administered as a large systemic dose, produces a persistent central block, despite being charged. The present study evaluated the cardiovascular effects of chlorisondamine. Shortly after administration, chlorisondamine (0.10, 1, and 10 mg/kg i.m.) lowered blood pressure significantly and decreased heart rate at the low dose (0.1 mg/kg i.m.) and increased heart rate at the high dose (10 mg/kg i.m.). Mecamylamine (1 and 10 mg/kg i.m.) also lowered blood pressure and heart rate. After both antagonists, heart rate returned to baseline values within 90 min and blood pressure within 24 h. Low doses of nicotine (0.01-0.03 mg/kg i.m.) lowered blood pressure but did not affect heart rate. Higher doses (0.10-3.2 mg/kg i.m.) transiently increased blood pressure and heart rate. Subsequent to antagonist administration, nicotine was administered to determine whether either drug blocked the cardiovascular effects of nicotine. Chlorisondamine (0.1, 1, and 10 mg/kg i.m.) administered 30 min before nicotine blocked the increases in blood pressure and heart rate. Only the high dose (10 mg/kg i.m.) of chlorisondamine administered 24 h before nicotine produced a blockade of nicotine's pressor effect. This block diminished within 3 days. Mecamylamine (1 mg/kg i.m.) antagonized only nicotine's tachycardic effect. Longer pretreatment with mecamylamine (10 mg/kg, 24 h before nicotine challenge) did not antagonize the cardiovascular effects of nicotine. Thus, chlorisondamine produces a longer lasting blockade of nicotine's cardiovascular effects than mecamylamine. The American Society for Pharmacology and Experimental Therapeutics