Effects of polyamines on contractility of guinea-pig gastric smooth muscle.
This study was designed to investigate the effects of polyamines on mechanical contraction and voltage-dependent calcium current (VDCC) of guinea-pig gastric smooth muscle. Mechanical contraction and calcium channel current I(Ba) were recorded by isometric tension recording and whole-cell patch clamp technique. Spermine, spermidine and putrescine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner. Spermine (2 mM) reduced high K+ (50 mM)-induced contraction to 16+/-6.4% of the control (n=9), and significantly inhibited I(Ba) in a reversible manner (p<0.05; IC50=0.8 mM). Pre- and post-treatment of tissue with spermine (2-5 mM, n=10) also inhibited acetylcholine (10 microM)-induced phasic contraction to 5+/-6.4% of the control. Inhibitory effect of spermine on I(Ba) was observed at a wide range of test potentials of current/voltage (I/V) relationship (p<0.05), and steady-state activation of I(Ba) was shifted to the right by spermine (p<0.05). Spermidine and putrescine (1 mM each) also inhibited I(Ba) to 51+/-5.7% and 81+/-5.3% of the control, respectively. And putrescine (1 mM) inhibited I(Ba) at whole tested potentials (p<0.05) without significant change of kinetics (p<0.05). Finally, 5 mM putrescine also inhibited high K+-induced contraction to 53+/-7.1% of the control (n=4). These findings suggest that polyamines inhibit contractions of guinea-pig gastric smooth muscle via inhibition of VDCC.
Kim
Young Chul
YC
Department of Physiology, Chungbuk National University, College of Medicine, Cheongju, Korea. physiokyc@chungbuk.ac.kr
Sim
Jae Hoon
JH
Kim
Young Ho
YH
Kwon
Seong-Chun
SC
Lee
Sang Jin
SJ
Kim
Seung Ryul
SR
Kim
Dong Woon
DW
Park
Seon-Mee
SM
Youn
Sei Jin
SJ
Lee
Sang-Jeon
SJ
Xing
De-Gang
DG
Xu
Wen-Xie
WX
Kim
Ki Whan
KW
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D011073:Polyamines / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011706:Pyloric Antrum / Q000187:drug effects* / Q000502:physiology
D015220:Calcium Channels; D011073:Polyamines; D011188:Potassium; D002118:Calcium