Intracellular free calcium and its modulation.

Over the past six years, Ca2+ channels have continued to receive much attention, partly as a result of their biological importance as excitation-response transducers, and partly as a result of exciting developments in enlightening their molecular properties and cellular functions. Neurotransmitter release, neurosecretion, neuronal excitation, survival of neurons, and many other neuronal functions are controlled by the cellular [Ca2+]. In turn the rise in [Ca2+]i modulates specific cellular functions. The enhancement of [Ca2+]i is modulated by various factors, peptidergic and not.