title: Effects of pine needle extract on pacemaker currents in interstitial cells of Cajal from the murine small intestine.
abstract: Extracts of pine needles (Pinus densiflora Sieb. et Zucc.) have diverse physiological and pharmacological actions. In this study we show that pine needle extract alters pacemaker currents in interstitial cells of Cajal (ICC) by modulating ATP-sensitive K+ channels and that this effect is mediated by prostaglandins. In whole cell patches at 30 degrees , ICC generated spontaneous pacemaker potentials in the current clamp mode (I = 0), and inward currents (pacemaker currents) in the voltage clamp mode at a holding potential of -70 mV. Pine needle extract hyperpolarized the membrane potential, and in voltage clamp mode decreased both the frequency and amplitude of the pacemaker currents, and increased the resting currents in the outward direction. It also inhibited the pacemaker currents in a dose-dependent manner. Because the effects of pine needle extract on pacemaker currents were the same as those of pinacidil (an ATP-sensitive K+ channel opener) we tested the effect of glibenclamide (an ATP-sensitive K+ channels blocker) on ICC exposed to pine needle extract. The effects of pine needle extract on pacemaker currents were blocked by glibenclamide. To see whether production of prostaglandins (PGs) is involved in the inhibitory effect of pine needle extract on pacemaker currents, we tested the effects of naproxen, a non-selective cyclooxygenase (COX-1 and COX-2) inhibitor, and AH6809, a prostaglandin EP1 and EP2 receptor antagonist. Naproxen and AH6809 blocked the inhibitory effects of pine needle extract on ICC. These results indicate that pine needle extract inhibits the pacemaker currents of ICC by activating ATP-sensitive K+ channels via the production of PGs.
authors.affiliation: Department of Physiology, College of Medicine, Chosun University, Gwangju 501-759, Korea.
authors.forename: Hyeonsook
authors.initials: H
authors.lastname: Cheong
authors.forename: Dilli Parasad
authors.initials: DP
authors.lastname: Paudyal
authors.forename: Jae Yeoul
authors.initials: JY
authors.lastname: Jun
authors.forename: Cheol Ho
authors.initials: CH
authors.lastname: Yeum
authors.forename: Pyung Jin
authors.initials: PJ
authors.lastname: Yoon
authors.forename: Chan Guk
authors.initials: CG
authors.lastname: Park
authors.forename: Man Yoo
authors.initials: MY
authors.lastname: Kim
authors.forename: Insuk
authors.initials: I
authors.lastname: So
authors.forename: Ki Whan
authors.initials: KW
authors.lastname: Kim
authors.forename: Seok
authors.initials: S
authors.lastname: Choi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005905:Glyburide / Q000494:pharmacology; D007421:Intestine, Small / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D009288:Naproxen / Q000494:pharmacology; D020110:Pinacidil / Q000494:pharmacology; D028223:Pinus / Q000737:chemistry*; D010936:Plant Extracts / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D011453:Prostaglandins / Q000096:biosynthesis / Q000502:physiology
chemical_list: D010936:Plant Extracts; D015221:Potassium Channels; D011453:Prostaglandins; D009288:Naproxen; D020110:Pinacidil; D000255:Adenosine Triphosphate; D005905:Glyburide