| Subcellular Ca2+ Mobilization in Gastric Smooth Muscle Contraction. |
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Kwang Soo Kim, Nam Sik Woo, Ye Chul Lee, Bo Kyung Kim, Jung Hwan Kim, Sung Il Cho |
1Department of Anesthesiology, College of Medicine, Konkuk University, Seoul, Korea. nswoo@konkuk.ac.kr
2Department of Physiology, College of Medicine, Konkuk University, Choongju, Korea. |
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| Abstract |
BACKGROUND
The stomach can be generally classified anatomically into three parts; fundus, corpus, and antrum.
It has not been well demonstrated how the three regions contribute to specified gastric motility. In the present study, the regional differences on contractile response and intracellular Ca2+ levels ([Ca2+]i) were investigated in a mouse gastric muscle.
METHODS
An isometrical contraction was measured with a computerized physiograph, and [Ca2+]i was measured with fura-PE3/AM, a fluorescent Ca2+ indicator in gastric smooth muscle from mice.
RESULTS
Carbachol (CCh), a potent muscarinic receptor agonist, generated rhythmic contractions in a dose dependent manner, superimposed on tonic components in the antral muscle. Whereas similar contractile responses to CCh was obtained in the antrum, CCh evoked tonic components predominantly. CCh increased [Ca2+]i in a dose dependent manner in both the antral and fundic smooth muscle.
However, the increment of [Ca2+]i in the fundus was greater than that of the antrum. Verapamil (10nM), a l-type Ca2+ channel blocker, inhibited completely the contraction and [Ca2+]i induced by CCh in the antral strips, whereas the responses in the fundus showed a resistance to verapamil.
CONCLUSIONS
These results suggest that muscarinic stimulation has a regional difference on muscle contractility and [Ca2+]i, which is mediated by differences of Ca2+ movement in mouse gastric muscle. |
| Key Words:
Contraction; intracellular Ca2+; muscarin agonist; stomach |
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