Arecoline excites the contraction of distal colonic smooth muscle strips in rats via the M3 receptor-extracellular Ca2+ influx - Ca2+ store release pathway.
Areca is a Chinese herbal medicine that is widely used for constipation. However the mechanisms of its action are not clear. We investigated the effects of arecoline, the most active component of areca, on the motility of rat distal colonic smooth muscle strips. In longitudinal muscle of distal colon (LMDC) and circular muscle of distal colon (CMDC), arecoline increased the contraction in a dose-dependent manner. Tetrodotoxin (TTX) did not inhibit the effects of arecoline. The contractile response to arecoline was completely antagonized by atropine. 4-Diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) strongly depressed the response to arecoline, but gallamine and methoctramine did not. Nifedipine, 2-aminoethoxydiphenyl borate (2-APB), and Ca2+-free Krebs solution with EGTA partly inhibited the effects of arecoline. The sum of Ca2+-free Krebs solution, EGTA, and 2-APB completely inhibited the effects of arecoline. The results show that arecoline stimulates distal colonic contraction in rats via the muscarinic (M3) receptor - extracellular Ca2+ influx - Ca2+ store release pathway. It is likely that the action of areca in relieving constipation is due to its stimulation of muscle contraction.
Li
Chuan-Bao
CB
Institute of Physiology, School of Medicine, Shandong University, 44 West Wenhua Road, Jinan, Shandong 250012, P. R. China.
Yang
Xiao
X
Tang
Wen-Bo
WB
Liu
Chuan-Yong
CY
Xie
Dong-Ping
DP
D000818:Animals; D001115:Arecoline / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D018679:Cholinergic Agonists / Q000494:pharmacology; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D003248:Constipation / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000627:therapeutic use; D005260:Female; D066298:In Vitro Techniques; D017136:Ion Transport; D018721:Muscarinic Agonists / Q000494:pharmacology*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D011913:Rats, Inbred BB; D043587:Receptor, Muscarinic M3 / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology
D018679:Cholinergic Agonists; D004365:Drugs, Chinese Herbal; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D043587:Receptor, Muscarinic M3; D013779:Tetrodotoxin; D001115:Arecoline; D002118:Calcium