Relaxant Effect of Spermidine on Acethylcholine and High K-induced Gastric Contractions of Guinea-Pig.
In our previous study, we found that spermine and putrescine inhibited spontaneous and acetylcholine (ACh)-induced contractions of guinea-pig stomach via inhibition of L-type voltage-dependent calcium current (VDCC(L)). In this study, we also studied the effect of spermidine on mechanical contractions and calcium channel current (I(Ba)), and then compared its effects to those by spermine and putrescine. Spermidine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner (IC(50)=1.1+/-0.11 mM). Relationship between inhibition of contraction and calcium current by spermidine was studied using 50 mM high K(+)-induced contraction: Spermidine (5 mM) significantly reduced high K(+) (50 mM)-induced contraction to 37+/-4.7% of the control (p<0.05), and inhibitory effect of spermidine on I(Ba) was also observed at a wide range of test potential in current/voltage (I/V) relationship. Pre- and post-application of spermidine (5 mM) also significantly inhibited carbachol (CCh) and ACh-induced initial and phasic contractions. Finally, caffeine (10 mM)-induced contraction which is activated by Ca(2+)-induced Ca(2+) release (CICR),' was also inhibited by pretreatment of spermidine (5 mM). These findings suggest that spermidine inhibits spontaneous and CCh-induced contraction via inhibition of VDCC(L) and Ca(2+) releasing mechanism in guinea-pig stomach.
Department of Physiology, Chungbuk National University College of Medicine, Cheongju 361-763, Korea.
Young Chul
YC
Kim
Jae Hoon
JH
Sim
Woong
W
Choi
Chan Hyung
CH
Kim
Ra-Young
RY
You
Wen-Xie
WX
Xu
Sang Jin
SJ
Lee