Expression of voltage-gated calcium channels correlates with PDGF-stimulated calcium influx and depends upon cell density in C3H 10T1/2 mouse fibroblasts.
Platelet derived growth factor (PDGF) mobilizes multiple calcium pools in the C3H 10T1/2 mouse fibroblast, including a sustained influx of extracellular calcium. We have used the whole cell patch-clamp technique to directly test for a role of plasma membrane calcium channels in this influx. Whole-cell patch-clamp recordings revealed a voltage-gated calcium channel with gating properties consistent with a 'T-type' designation. This phenotype of the C3H 10T1/2 fibroblasts was dependent upon the cell density in culture. The fraction of cells expressing calcium channels was low (< 10%) in subconfluent culture but rose to approximately 50% as the cells established a confluent monolayer. The magnitude of the PDGF-stimulated sustained calcium influx component measured using Fura-2 increased in parallel with the expression of calcium current. We interpret these results to support the hypothesis that T-type voltage-gated calcium channels contribute to the PDGF-stimulated intracellular calcium signals in these cells.
Estacion
M
M
Molecular Oncology Program, Cancer Research Center of Hawaii, Honolulu.
Mordan
L J
LJ
D000818:Animals; D001464:Barium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects; D002452:Cell Count; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology*; D015640:Ion Channel Gating; D008564:Membrane Potentials; D051379:Mice; D008809:Mice, Inbred C3H; D010641:Phenotype; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
D015220:Calcium Channels; D010982:Platelet-Derived Growth Factor; D001464:Barium; D002118:Calcium