Journal of Neuroscience, Vol 5, 1680-1687, Copyright © 1985 by Society for Neuroscience
Potassium-stimulated purine release by cultured sympathetic neurons
EJ Wolinsky and PH Patterson
Environmental factors can influence cultured sympathetic neurons to acquire
several different neurotransmitter phenotypes. Cholinergic and
noradrenergic transmitter status can be influenced by heart cell
conditioned medium, chronic depolarization (Patterson, P. H. (1978) Annu.
Rev. Neurosci. 1:1-17), and rat serum (Wolinsky, E. J., and P. H.
Patterson, (1985) J. Neurosci. 5:1509-1512); formation of electrical
synapses can be induced by insulin (Wolinsky, E. J., H. Patterson, and A.
L. Willard (1985) J. Neurosci., 5:1675-1679). Purine release has also been
proposed as a possible transmission mode for sympathetic neurons (Potter,
D. D., E. J. Furshpan, and S. C. Landis (1983) Fred. Proc. 42:1626-1632),
and as such, it is another candidate for environmental modulation. In this
report, we assess the ability of sympathetic neuron cultures grown with and
without serum to release metabolically labeled tritriated purine compounds
in response to depolarization. Exposure to 54 mM potassium stimulated
release of adenosine, inosine, and hypoxanthine from both
serum-supplemented and defined-medium cultures. However,
depolarization-stimulated release of adenine nucleotides was observed only
from serum-supplemented cultures and not from serum-free cultures. The
release of adenine nucleotides from serum-containing cultures is affected
by divalent cations in the manner expected for a neurosecretory process.
The failure of serum-free cultures to release detectable adenine
nucleotides raises the possibility that they do not share with, or that
they differ from, serum-supplemented cultures in the purinergic aspect of
the multiple transmission modes available to sympathetic neurons, and that
this difference may be due to effects of the culture medium.