マウス小腸ペースメーカー電位に対する温度の影響について

抄録

Interstitial cells of Cajal distributed in myenteric region (ICC-MY) generate spontaneous electrical activity called pacemaker potential in gastrointestinal tract. Pacemaker potentials recorded from mouse small intestine have two components: rapidly rising primary component and following plateau component. In the present study the effects of temperature on the generation of pacemaker potentials were studied with conventional microelectrode techniques. Elevation of temperature increased the frequency and maximum rate of rise (dV/dt_max) of pacemaker potentials and decreased their duration, without affecting the resting membrane potential and amplitude. CPA (3μM), an inhibitor of internal Ca pump, abolished pacemaker potentials at around 28°C, while CPA only shortened the duration of pacemaker potentials with the depolarization of the membrane at around 40°C. KCN (30μM), an inhibitor of metabolic process in mitochondria, decreased the frequency of pacemaker potentials without changing the amplitude and dV/dt_max. These results suggest that the sensitivity to temperature is different between two components (primary and plateau) of pacemaker potentials. The primary component may be generated by the activation of temperature sensitive Ca permeable channels. On the other hand, the plateau component seems to be generated by temperature insensitive mechanisms. The results also suggest that mitochondrial function seems to be uninvolved in the formation of two components of pacemaker potentials. [J Physiol Sci. 2006;56 Suppl:S79]