title: Poncirus trifoliate fruit modulates pacemaker activity in interstitial cells of Cajal from the murine small intestine.
abstract: BACKGROUND
  Poncirus fructus (PF) has been widely used as a traditional medicine in Eastern Asia, especially to ameliorate the symptoms of gastrointestinal (GI) disorders related to abnormal GI motility.
  
  
  OBJECTIVE
  Poncirus fructus (PF), also known as Poncirus trifoliata (L.) Raf. (Rutaceae), is widely used as a traditional medicine in Eastern Asia mainly to ameliorate the symptoms of gastrointestinal (GI) disorders related to abnormal GI motility. In a previous study, a methanol extract of PF was found to have particularly potent gastroprokinetic effects. Interstitial cells of Cajal (ICCs) are pacemaker cells in the gastrointestinal tract, but the action mechanisms of PF extract in mouse small intestinal ICCs have not been investigated. Therefore, in the present study, we investigated the effects of a methanol extract of PF (MPF) in mouse small intestinal ICCs. In addition, we sought to identify the receptors involved.
  
  
  METHODS
  Enzymatic digestions were used to dissociate ICCs from small intestines. The whole-cell patch-clamp configuration was used to record potentials (current clamp) from cultured ICCs. In addition, we analyzed intracellular Ca(2+) concentrations ([Ca(2+)]i).
  
  
  RESULTS
  MPF decreased the amplitudes of pacemaker potentials in ICCs, and depolarized resting membrane potentials in a concentration dependent manner. Y25130 (a 5-HT3 receptor antagonist) and RS39604 (a 5-HT4 receptor antagonist) blocked MPF-induced membrane depolarizations, whereas SB269970 (a 5-HT7 receptor antagonist) did not. Pretreatment with Na(+) or Ca(2+)-free solution or thapsigargin (a Ca(2+)-ATPase inhibitor in endoplasmic reticulum) abolished the generation of pacemaker potentials and suppressed MPF-induced activity. [Ca(2+)]i analysis showed that MPF increased [Ca(2+)]i. Furthermore, treatments with PD 98059, SB203580, or JNK II inhibitor blocked MPF-induced membrane depolarizations in ICCs.
  
  
  CONCLUSIONS
  These results suggest that MPF modulates pacemaker potentials through 5-HT3 and 5-HT4 receptor-mediated pathways via external Na(+) and Ca(2+) influx, and via Ca(2+) release from internal stores in a mitogen-activated protein kinase dependent manner. The study shows MPF is a good candidate for the development of a gastroprokinetic agent. In view of the effects of MPF on ICCs, further research is required, particularly to identify the active compound(s) involved and to determine their action mechanisms.
authors.affiliation: Division of Longevity and Biofunctional Medicine, Pusan National University School of Korean Medicine, Yangsan 626-870, Republic of Korea.
authors.forename: Byung Joo
authors.initials: BJ
authors.lastname: Kim
authors.forename: Hyung Woo
authors.initials: HW
authors.lastname: Kim
authors.forename: Guem San
authors.initials: GS
authors.lastname: Lee
authors.forename: Seok
authors.initials: S
authors.lastname: Choi
authors.forename: Jae Yeoul
authors.initials: JY
authors.lastname: Jun
authors.forename: Insuk
authors.initials: I
authors.lastname: So
authors.forename: Seon Jeong
authors.initials: SJ
authors.lastname: Kim
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D005638:Fruit / Q000737:chemistry; D005769:Gastrointestinal Motility / Q000187:drug effects*; D056885:Interstitial Cells of Cajal / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D007421:Intestine, Small / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D008297:Male; D008518:Medicine, East Asian Traditional; D000090204:Mesothelin; D051379:Mice; D008807:Mice, Inbred BALB C; D018408:Patch-Clamp Techniques; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D032104:Poncirus / Q000737:chemistry*; D011985:Receptors, Serotonin / Q000378:metabolism
chemical_list: C000715528:Msln protein, mouse; D010936:Plant Extracts; D011985:Receptors, Serotonin; D000090204:Mesothelin; D002118:Calcium
keywords: 5-hydroxytryptamine; Gastrointestinal Motility; Interstitial Cells of Cajal; Poncirus trifoliata (L.) Raf. (Rutaceae)