DIRECT CONTRACTILE EFFECT OF MOTILIN ON ISOLATED SMOOTH-MUSCLE CELLS OF GUINEA-PIG SMALL-INTESTINE

被引:23
作者
HARADA, N
CHIJIIWA, Y
MISAWA, T
YOSHINAGA, M
NAWATA, H
机构
[1] The Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka
关键词
D O I
10.1016/0024-3205(92)90638-6
中图分类号
R-3 [医学研究方法]; R3 [基础医学];
学科分类号
1001 ;
摘要
We examined the direct effect of motilin on longitudinal and circular smooth muscle cells isolated from the guinea pig small intestine. In addition, the effects of 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8, an inhibitor of intracellular Ca2+-release), verapamil (a voltage-dependent Ca2+-channel blocker), and removal of extracellular Ca2+ were investigated to evaluate the role of intracellular Ca2+ stores and extracellular Ca2+ on the muscle contraction induced by motilin. The effects of atropine (a muscarinic receptor antagonist), spantide (a substance P receptor antagonist) and loxiglumide (a CCK-receptor antagonist) were also examined to determine whether the motilin-induced contraction was independent of those receptors. Motilin induced a contraction of the longitudinal and circular smooth muscle cells in a dose-dependent manner with the maximal effect attained after 30 seconds of incubation. The ED o values were 0.3 nM and 0.05 nM, respectively. TmB-8 suppressed completely the motilin-induced contraction of both types of smooth muscle cells. Verapamil had only a slight suppressive effect. Removal of extracellular Ca2+ did not have any significant influence on motilin-induced contraction. The contractile response to motilin was not affected by atropine, spantide or loxiglumide. Our findings showed that:l) motilin has a direct contractile effect on both longitudinal and circular smooth muscle cells; 2) this contractile effect is not evoked via muscarinic, substance P or CCK receptors, and 3) the intracellular release of Ca2+ plays an important role in the contractile response to motilin on both types of smooth muscle cells.
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收藏
页码:1381 / 1387
页数:7
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