Neuromuscular blocking activity of methanolic extract of Piper sarmentosum leaves in the rat phrenic nerve-hemidiaphragm preparation.
Methanolic extract of Piper sarmentosum Roxb. (Piperaceae) leaves was studied for the neuromuscular blocking activity in rat phrenic nerve-hemidiaphragm preparations. The plant extract, at concentrations of 3.2, 4.0, 4.8 and 6.4 mg/ml, exhibited an initially transient increase in twitch tension which was followed by a marked dose-related neurally-evoked twitch depression. The neuromuscular blocking effect produced by the plant extract was compared with d-tubocurarine (dTC) and succinylcholine (SCh). The EC50 for neurally-evoked twitch depression of the extract, dTC and SCh was 4.07 mg/ml, 1.1 microM and 15 microM, respectively. The neurally-evoked twitch depression produced by the extract was partially antagonized by tetraethylammonium (TEA) but not by neostigmine (NS). These findings suggested that the plant extract possessed a marked neuromuscular blocking activity at the neuromuscular junction and a possible mechanism which was likely to inhibit neurotransmitter (acetylcholine) release at the presynaptic terminal.
Department of Pharmacology, Faculty of Science, Prince of Songkla University, Hat Yai, Thailand.
W
W
Ridtitid
W
W
Rattanaprom
P
P
Thaina
S
S
Chittrakarn
M
M
Sunbhanich
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003964:Diaphragm / Q000187:drug effects*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D000432:Methanol; D009119:Muscle Contraction / Q000187:drug effects; D009466:Neuromuscular Blocking Agents / Q000302:isolation & purification / Q000494:pharmacology*; D010791:Phrenic Nerve / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000187:drug effects; D012997:Solvents; D013390:Succinylcholine / Q000494:pharmacology; D014403:Tubocurarine / Q000494:pharmacology
D009466:Neuromuscular Blocking Agents; D010936:Plant Extracts; D012997:Solvents; D013390:Succinylcholine; D014403:Tubocurarine; D000432:Methanol