Abstract
We feel a wide range of temperatures spanning from cold to heat. Within this range, temperatures over about 43°C and below about 15°C evoke not only a thermal sensation, but also a feeling of pain. The first found molecule detecting ambient temperatures is capsaicin receptor TRPV1 which belongs to a large TRP ion channel super family and can be activated by elevated temperatures with a discrete threshold near 43°C. Three other TRPV channels, TRPV2, TRPV3 and TRPV4 have been cloned and characterized as heat or warm thermosensors. In addition, three of TRPM channels (TRPM2, TRPM4 and TRPM5) have been reported to be thermosensitive. The threshold temperatures for activation of these channels range from relatively warm (TRPV3, TRPV4, TRPM2, TRPM4 and TRPM5) to extremely hot (TRPV2). In contrast to these warmth- or heat-activated TRP channels, two other TRP channels, TRPM8 and TRPA1 have been found to be activated by cold stimuli although cold sensitivity of TRPA1 is controversial. Thus, there are nine TRP channels to be thermosensitive, and the fact that five TRP channels can be activated by warm stimuli suggests that many cells in our body are sensing ambient temperatures. I would like to present our recent works about warmth-sensitive TRPV3, TRPV4 and TRPM2 channels. [J Physiol Sci. 2007;57 Suppl:S27]
