title: 5-hydroxytryptamine generates tonic inward currents on pacemaker activity of interstitial cells of cajal from mouse small intestine.
abstract: In this study we determined whether or not 5-hydroxytryptamine (5-HT) has an effect on the pacemaker activities of interstitial cells of Cajal (ICC) from the mouse small intestine. The actions of 5-HT on pacemaker activities were investigated using a whole-cell patch-clamp technique, intracellular Ca(2+) ([Ca(2+)](i)) analysis, and RT-PCR in ICC. Exogenously-treated 5-HT showed tonic inward currents on pacemaker currents in ICC under the voltage-clamp mode in a dose-dependent manner. Based on RT-PCR results, we found the existence of 5-HT(2B, 3, 4, and 7) receptors in ICC. However, SDZ 205557 (a 5-HT(4) receptor antagonist), SB 269970 (a 5-HT7 receptor antagonist), 3-tropanylindole - 3 - carboxylate methiodide (3-TCM; a 5-HT(3) antagonist) blocked the 5-HT-induced action on pacemaker activity, but not SB 204741 (a 5-HT(2B) receptor antagonist). Based on [Ca(2+)](i) analysis, we found that 5-HT increased the intensity of [Ca(2+)](i). The treatment of PD 98059 or JNK II inhibitor blocked the 5-HT-induced action on pacemaker activity of ICC, but not SB 203580. In summary, these results suggest that 5-HT can modulate pacemaker activity through 5-HT(3, 4, and 7) receptors via [Ca(2+)](i) mobilization and regulation of mitogen-activated protein kinases.
authors.affiliation: Department of Physiology, College of Medicine, Chosun University, Gwangju 501-759, Korea.
authors.forename: Pawan Kumar
authors.initials: PK
authors.lastname: Shahi
authors.forename: Seok
authors.initials: S
authors.lastname: Choi
authors.forename: Dong Chuan
authors.initials: DC
authors.lastname: Zuo
authors.forename: Cheol Ho
authors.initials: CH
authors.lastname: Yeum
authors.forename: Pyung Jin
authors.initials: PJ
authors.lastname: Yoon
authors.forename: Jun
authors.initials: J
authors.lastname: Lee
authors.forename: Young Dae
authors.initials: YD
authors.lastname: Kim
authors.forename: Chan Guk
authors.initials: CG
authors.lastname: Park
authors.forename: Man Yoo
authors.initials: MY
authors.lastname: Kim
authors.forename: Hye Rang
authors.initials: HR
authors.lastname: Shin
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Oh
authors.forename: Jae Yeoul
authors.initials: JY
authors.lastname: Jun