抄録
Heating of cells produce various immediate cellular events including activation of ion channels. However, the effects of heat on ion channels in cardiac myocytes remain unclear. In this study, we examined the effect of heat on L-type Ca2+ channels in guinea-pig ventricular myocytes, using the patch clamp method. Heating of the myocytes (45°C, 30 min) increased the L-type Ca2+ current about 4-fold. After the heat treatment, forskolin failed to further increase the L-type Ca2+ current. The increase of L-type Ca2+ current induced by heating was greatly attenuated (to 1.5-2 fold) by pre-treatment of the myocytes with an inhibitor of protein kinase A (PKA), H-89 (5 μM) or a non-specific protein kinase inhibitor, K-252a (0.5 μM). Furthermore, the heat treatment shifted the I-V curve of the L-type Ca2+ current to the hyperpolarizing direction by about 8 mV. This shift of the I-V curve was prevented by the pre-treatment with H-89 or K-252a. These results suggested that heating of the myocytes may promote phosphorylation of the L-type Ca2+ channels through activation of PKA and/or inactivation of counteracting protein phosphatases. [J Physiol Sci. 2007;57 Suppl:S229]
