Stimulatory effect of trans-cinnamaldehyde on noradrenaline secretion in guinea-pig ileum myenteric nerve terminals.
The effect of trans-cinnamaldehyde (CNMA) on the release of noradrenaline (NA) from nerve terminal was investigated using isolated ileal synaptosomes of guinea-pig. Release was determined as the amount of NA, quantified by h.p.l.c.-electrochemical detection, from samples incubated with CNMA minus that in parallel blanks treated with same volume of vehicle. CNMA stimulated the secretion of NA in a concentration-dependent manner from 5 microM to 50 microM, while the value of lactate dehydrogenase in the incubated medium was not influenced by CNMA. However, trans-cinnamic acid, cinnamoyl chloride and cinnamamide failed to produce similar effect. Specific action of CNMA can thus be considered. Guanethidine inhibited the release of NA by CNMA in a concentration- dependent manner. Saxitoxin attenuated the action of CNMA at concentrations sufficient to block sodium channels. The depolarizing effect of CNMA on the membrane potential was also illustrated by a concentration-dependent increase in the fluorescence of bisoxonol, a potential sensitive dye. The NA releasing action of CNMA was deleted by removal of calcium chloride from the bathing medium. This action of CNMA was also attenuated by Rp-cAMP at concentrations sufficient to inhibit the action of cyclic AMP. These findings suggest that CNMA can depolarize the membrane to result in a calcium-dependent and cyclic AMP-related release of NA from noradrenergic terminals.
Cheng
J T
JT
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan City, Taiwan, ROC. jtcheng@mail.ncku.edu.tw
Liu
I M
IM
Huang
W C
WC
Kou
D H
DH
D000171:Acrolein / Q000031:analogs & derivatives* / Q000494:pharmacology; D018674:Adrenergic Antagonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology; D000242:Cyclic AMP / Q000502:physiology; D005260:Female; D006145:Guanethidine / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects* / Q000201:enzymology / Q000294:innervation; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009411:Nerve Endings / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000378:metabolism*
D018674:Adrenergic Antagonists; D000171:Acrolein; D000242:Cyclic AMP; D007770:L-Lactate Dehydrogenase; C012843:cinnamaldehyde; D002118:Calcium; D009638:Norepinephrine; D006145:Guanethidine