The role of voltage-gated calcium channels in neurotransmitter phenotype specification: Coexpression and functional analysis in Xenopus laevis.
Bottom Line: Calcium activity was also analyzed on a single-cell level, and spike frequency was correlated with the expression of VGCC α1 subunits in cell culture.Cells expressing Cav 2.1 and Cav 2.2 displayed increased calcium spiking compared with cells not expressing this marker.The VGCC antagonist diltiazem and agonist (-)BayK 8644 were used to manipulate calcium activity.
Affiliation: Department of Biology, College of William and Mary, Williamsburg, Virginia, 23185.Show MeSH
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Mentions: To determine which, if any, VGCC α1 subunits are coexpressed with excitatory neurotransmitter markers, multiplex FISH analysis was performed, probing for VGCC markers and xVGlut1. VGCC α1 subunits are highly coexpressed with the glutamatergic marker throughout the developing nervous system, although many neurons expressing VGCCs do not express the neurotransmitter marker and vice versa (Table2). In the forebrain, xVGlut1 is coexpressed with Cav1.2 in the dorsalmost tip (Fig. 1A), whereas overlap of Cav1.3 and xVGlut1 occurs in a medial band extending from the dorsal end of the forebrain (Fig. 1F). xVGlut1 coexpression also occurs along the lateral edge of the forebrain with Cav2.1 and Cav2.2 (Fig. 1K,P). Coexpression in the midbrain is highest between xVGlut1 and Cav3.1 and is found in a ventral lateral region (Fig. 1U). xVGlut1 coexpression is also found with Cav1.2 and Cav2.1 in the lateral midbrain (Fig. 1B,L). xVGlut1 is coexpressed with Cav1.3 and Cav3.1 in the ventral hindbrain and in the spinal cord interneurons (Fig. 1H–J,V,W). Additional coexpression occurs with Cav2.2 along the lateral edge of the spinal cord (Fig. 1S). Very little coexpression is found in the retina, although Cav2.1 and xVGlut1 do overlap in the ganglion cell layer (GCL) (Fig. 2D). In the cranial nerves, coexpression is found between xVGlut1 and VGCCs in every cell in this region (Fig. 1G,M,R,V,W,Y,Z).
Affiliation: Department of Biology, College of William and Mary, Williamsburg, Virginia, 23185.