Study of the frequency regulatory mechanism of the slow wave in mammalian small intestine

Research Project

Project/Area Number	62570982
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Biological pharmacy
Research Institution	Kanazawa University
Principal Investigator	SUZUKI Nagao Kanazawa Univ. Fac. of Pharmc. Sci. Assoc. Professor, 薬学部, 助教授 (50092250)
Project Period (FY)	1987 – 1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥1,500,000 (Direct Cost: ¥1,500,000) Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1987: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywords	Slow wave / Small intestine / Frequency regulation / cAMP / 神経伝達物質 / 分節運動 / 周期性 / サイクリックAMP
Research Abstract	Slow wave in the mammalian small intestine is a rhythmic depolarization of 2-5 sec duration, forming the basis of rhythmic contractions such as the pendulum or segmenttion. The slow wave has been suggested to originate in the interstitial cells of Cajal located in the Auerbach plexus of the small intestine. In the present study, mechanism of the regulation of the slow wave frequency was pursued by finding the drugs which can modulate the rhythmicity of the slow waves. Slight increase of the potassium concentration in the bathing solution decreased the frequency of slow wave, and induced the ectopic focus generating the slow wave of different frequency. Dibutyryl cyclic AMP or the drugs which have been shown to increase the content of intracellular cyclic AMP (cAMP) in various types of cells decreased the frequency of slow waves. However, drugs known to increase the cAMP content in the smooth muscle cells did not affect the frequency of the slow wave. Addition of Ca did not counteract the effects of cAMP. These results suggest that the regulation of slow wave frequency was made by neurotransmitters released from the nerves in the Auerbach plexus acting on the Interstitial cells of Cajal through the second messenger of cAMP.