Em. Elliott et al., ROLE OF CALCIUM-CHANNEL SUBTYPES IN CALCIUM TRANSIENTS IN HIPPOCAMPALCA3 NEURONS, The Journal of neuroscience, 15(10), 1995, pp. 6433-6444
Multiple subtypes of voltage-gated calcium channels are differentially
localized in brain neurons suggesting that they serve distinct roles
in neuronal excitation and signaling. In organotypic hippocampal slice
cultures, class D (L-type) calcium channels are predominantly located
in the cell bodies of CA3 neurons while class B (N-type) and class A
(P or Q-type) are localized in dendrites and associated presynaptic te
rminals with relatively low somal expression. Using specific antagonis
ts to inhibit calcium transients recorded in CA3 neuronal cell bodies,
we found that L-type calcium channels have a predominant role in soma
l calcium transients elicited by trains of strong stimuli applied to e
ither the soma or the distal apical dendrite while class A calcium cha
nnels make a smaller contribution. Presynaptic class B (N-type) and cl
ass A (P- and/or Q-type) calcium channels are critical for glutamate-m
ediated synaptic transmission onto the dendrites of CA3 neurons. Posts
ynaptic class A and B calcium channels detected on the dendritic shaft
by immunocytochemistry were not found to contribute substantially to
somal calcium transients during repetitive stimulation of distal dendr
ites, but sodium channels were required for calcium transients elicite
d by somatic or dendritic stimulation. Our results show that the diffe
rent calcium channel subtypes serve distinct roles in cellular activat
ion and transmission of signals in CA3 neurons, consistent with their
differential subcellular localization.