| Popis: |
Voltage-dependent calcium channels are present in all neurons. They are closed at normal resting potentials, and they open when a membrane is depolarized by an action potential. One important function of calcium channels in neurons is to mediate release of neurotransmitter from presynaptic nerve terminals. In addition, calcium channels help initiate electrical action potentials in various cell bodies and dendrites. It is very likely that calcium entry through voltage-dependent calcium channels is also important for a whole range of phenomena triggered by increases in internal calcium levels. Among these phenomena may be cell death resulting from prolonged calcium entry subsequent to long-lasting depolarizations, as may occur during ischemia. |
