A mathematical model of pacemaker activity recorded from mouse small intestine.
The pacemaker activity of interstitial cells of Cajal (ICCs) has been known to initiate the propagation of slow waves along the whole gastrointestinal tract through spontaneous and repetitive generation of action potentials. We studied the mechanism of the pacemaker activity of ICCs in the mouse small intestine and tested it using a mathematical model. The model includes ion channels, exchanger, pumps and intracellular machinery for Ca2+ regulation. The model also incorporates inositol 1,4,5-triphosphate (IP3) production and IP3-mediated Ca2+ release activities. Most of the parameters were obtained from the literature and were modified to fit the experimental results of ICCs from mouse small intestine. We were then able to compose a mathematical model that simulates the pacemaker activity of ICCs. The model generates pacemaker potentials regularly and repetitively as long as the simulation continues. The frequency was set at 20 min(-1) and the duration at 50% repolarization was 639 ms. The resting and overshoot potentials were -78 and +1.2 mV, respectively. The reconstructed pacemaker potentials closely matched those obtained from animal experiments. The model supports the idea that cyclic changes in [Ca2+]i and [IP3] play key roles in the generation of ICC pacemaker activity in the mouse small intestine.
Youm
Jae Boum
JB
Mitochondrial Signaling Laboratory, Department of Physiology and Biophysics, College of Medicine, 2020 Cardiovascular Institute, Inje University Busan 614-735, South Korea.
Kim
Nari
N
Han
Jin
J
Kim
Euiyong
E
Joo
Hyun
H
Leem
Chae Hun
CH
Goto
Gazunori
G
Noma
Akinori
A
Earm
Yung E
YE
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D003198:Computer Simulation; D005769:Gastrointestinal Motility / Q000502:physiology*; D007421:Intestine, Small / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*