Voltage-dependent calcium channels present in vertebrate cells play important roles in excitation-contraction coupling mechanisms and signal transduction. These channels are
classsified into L, N, P and T-types, based on their electrophysiologic and pharmacologic properties.
The localization of α1 subunit of L-type and P-type calcium channels in adult rat brain and 19 days old rat embryo were analyzed by in situ hybridization histochemistry. The mRNA for the P-type voltage dependent calcium channel α1
subunit
was
prominently localized in Purkinje cell layer of cerebellum, CA3 regions of hippocampus and inferior colliculus. In the 19 days old embryo, L-type channel expressed not only in the nervous system but also in the nonneuronal tissues but
P-type
channel was exclusively localized in the neuronal tissues.
Thus, regional distribution of L-and P-type calcium channel mRNA in rat brain suggests that these types of calcium channels may play an important role in excitation-secretion coupling functions in the neuroendocrine system and in inducing
long-term
depression in the cerebellar cortex, respectively.
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