Mouse postganglionic sympathetic neurons: Primary culturing and noradrenaline release

Basic properties of noradrenaline release were studied in primary cultures of thoracolumbar postganglionic sympathetic neurons taken from 1-3-day-old NMRI mice. After 7 days in vitro, the cultures were preincubated with [H-3] noradrenaline and then superfused and stimulated electrically. Conventional trains of pulses (for example, 36 pulses at 3 Hz) as well as single pulses and brief high-frequency trains (for example, four pulses at 100 Hz) elici ted a well-measurable overflow of tritium, which was abolished by 0.3 mu M tetrodotoxin or omission of Ca2+, but not changed by 1 mu M rauwolscine. in trains of one, two, four, six, eight, or 10 pulses at 3 Hz, the evoked ove rflow of tritium remained constant from pulse to pulse at 1.3 mM Ca2+, but declined slightly at 2.5 mM Ca2+ Tetraethylammonium at 10 mM selectively in creased the overflow elicited by small pulse numbers and especially by a si ngle pulse. In trains of 10 pulses delivered at 0.3, 1, 3, 10, 30, or 100 H z, the evoked overflow of tritium increased from 0.3 to 30 Hz and then decl ined at 100 Hz. This relationship was particularly pronounced at low Ca2+ c oncentrations (for example, 0.3 mM), Tetraethylammonium at 10 mM selectivel y increased the overflow elicited by low frequencies of stimulation, It is concluded that primary cultures of mouse postganglionic sympathetic neurons can be used to investigate release of [H-3]noradrenaline. The release is w ell measurable, even upon a single electrical pulse. It agrees with release in intact sympathetically innervated tissues in a number of fundamental pr operties, including the pulse number and frequency dependence. The preparat ion may be of special interest in conjunction with genetic manipulations in the donor animals.