IGF-I enhances survival of embryonic chick ciliary ganglion neurons in a calcium-dependent way.

We have shown that neurons from embryonic chick ciliary ganglia in primary culture possess receptors for insulin-like growth factor I (IGF-I). When added to serum- and insulin-free culture medium, the factor potently enhanced neuronal survival as observed after 24 and 48 h of culture. The effect saturated at 5 ng/ml.

Alpha-latrotoxin channels in neuroblastoma cells.

The changes in ionic permeability induced by the application of alpha-latrotoxin to NG108-15 neuroblastoma x glioma cells were examined using the nystatin perforated-patch technique for whole-cell recording. Complex single channel activity appeared in the plasmalemmas after delays that ranged from 1-20 min in Krebs' solution. The conductance of a channel fluctuated among at least three broad, approximately equispaced bands, the maximum conductance being about 300 pS, and the reversal potential approximately 0 mV.

Sodium-activated potassium current in sensory neurons: a comparison of cell-attached and cell-free single-channel activities.

Single-channel currents from Na(+)-dependent K+ channels (KNa) were recorded from cell-attached and inside-out membrane patches of cultured avian trigeminal ganglion neurons by means of the patch-clamp technique. Single-channel properties, such as the high elementary conductance and the occurrence of sub-conductance levels, were unchanged after the patches had been excised from the cells, indicating that they are not under the control of soluble cytoplasmic factors. In cell-attached recordings at the cell resting potential the degree of KNa activity, measured as the probability of the channel being open, Po, was low in most cases (around 0.

Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons.

Whole-cell voltage clamp and single-channel recordings were performed on cultured trigeminal ganglion neurons from quail embryos in order to study a sodium-activated potassium current (KNa). When KNa was activated by a step depolarization in voltage clamp, there was a proportionality between KNa and INa at all voltages between the threshold of INa and ENa. Single-channel recordings indicated that KNa could be activated already by 12 mM intracellular sodium and was almost fully activated at 50 mM sodium.