Enhancement of the Ca2(+)-current by a serum factor in cultured dorsal root ganglia neurons of the adult guinea pig.
To investigate effects of serum factor on the Ca2(+)-spike and neurite outgrowth in cultured nerve cells, dorsal root ganglia (DRG) neurons of the adult guinea pig were cultured in a serum-free N1 medium (N1 group) and a serum-containing medium (FCS group). The maximum rate of rise (MRR) of the Ca2(+)-spike, an indicator of the maximum Ca2(+)-current, was enhanced in the FCS group on day 5 in culture. The MRR of Ca2(+)-spike remained at a low level in the N1 group (2-10 days), but neurites outgrew rapidly during 2-5 days in both the FCS and N1 groups. Replacement of a serum-free medium by a serum-containing one on day 5 caused faster increase in the MRR of the Ca2(+)-spike. The active serum component for the Ca2(+)-spike enhancement was a heat-stable, small molecule. Chronic application of dibutyryl cyclic AMP (10 microM) mimicked the serum action on the Ca2(+)-spike. Whole-cell voltage-clamp experiment by a patch electrode showed that currents through the L- and T-type Ca-channels were enhanced in FCS group. Since kinetic and voltage-dependent gating properties of Ca-channels were similar between the FCS and N1 groups, available channel density might be increased by a serum factor.
Yamaguchi
K
K
Department of Physiology, Faculty of Medicine, University of Tokyo, Japan.
D000818:Animals; D015220:Calcium Channels / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003470:Culture Media; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D012964:Sodium / Q000494:pharmacology; D013324:Strontium / Q000494:pharmacology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015220:Calcium Channels; D003470:Culture Media; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D012964:Sodium; D013324:Strontium