| Popis: |
A number of 5-HT actions where the mechanism is one of opening an ion channel, resulting in a fast depolarization, a slow depolarization or a hyperpolarization are compared with actions where the mechanism is a closure of ion channels, resulting in a slow depolarization, altered transmitter release or altered membrane accommodation. The relationship of these mechanisms to a particular receptor subtype and to a particular second messenger system is likely to become apparent in the near future. At present, the extent to which differentiation of an electrophysiological action of 5-HT in terms of mechanism is predictive of involvement of a particular 5-HT receptor is unclear. Evidence from the nervous system suggests that a particular mechanism is usually associated with a certain sub-type of 5-HT receptor and, thus, classification by function provides a useful initial framework provided it does not become a dogma. |
