Effects of Pine Needle Extract on Spontaneous Pacemaker Potentials in Interstitial Cells of Cajal from the Mouse Colon
2013
Shahi, P.K., Chosun University, Gwangju, Republic of Korea | Zuo, D.C., Chosun University, Gwangju, Republic of Korea | Choi, S., Chosun University, Gwangju, Republic of Korea | Lee, M.J., Chosun University, Gwangju, Republic of Korea | Cheong, H.S., Chosun University, Gwangju, Republic of Korea | Lim, D.Y., Chosun University, Gwangju, Republic of Korea | Jun, J.Y., Chosun University, Gwangju, Republic of Korea
In preliminary tests, we examined the effect of several fractions isolated from fermented pine needle extract on pacemaker potentials in cultured interstitial cells of Cajal (ICCs) from the mouse colon using a whole cell patch clamp technique. Among these fractions, Fraction 3 (F3) elicited the most powerful depolarization of membrane. Therefore, the aim of the present study was to investigate the effect of F3 obtained from fermented extract of Pinus densiflora needle on pacemaker potentials in ICCs and to establish its mechanism of action. Colonic ICCs generated spontaneous periodic pacemaker potentials in the current-clamp mode. F3 depolarized the membrane and decreased the frequency and amplitude of pacemaker potentials in a dose-dependent fashion. The F3-induced effects on pacemaker potentials were blocked by methoctramine, a muscarinic M2 receptor antagonist, and by glycopyrrolate, a muscarinic M3 receptor antagonist. The F3-induced effects on pacemaker potentials were blocked by external Na+-free solution and by flufenamic acid, a non-selective cation channel blocker, as well as by the removal of external Ca2+ and in the presence of thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum. Taken together, these results suggest that F3 of pine needle extract modulates the pacemaker activity of colonic ICCs by the activation of non-selective cation channels via muscarinic M2 and M3 receptors. And external Ca2+ influx and intracellular Ca2+ release are involved in F3 actions on ICCs.
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