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Gap junction coupling‐mediated membrane potential oscillations drive activity in cutaneous but not muscle vasoconstrictor sympathetic preganglionic neurones in situ
Author(s) -
Stalbovskiy Alexey O,
Paton Julian F,
Pickering Anthony E
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.611.9
Subject(s) - antidromic , depolarization , hyperpolarization (physics) , membrane potential , excitatory postsynaptic potential , electrophysiology , bursting , neuroscience , chemistry , population , coupling (piping) , biophysics , anatomy , biology , inhibitory postsynaptic potential , medicine , stereochemistry , mechanical engineering , environmental health , nuclear magnetic resonance spectroscopy , engineering
A population of sympathetic preganglionic neurones (SPN) recorded in vitro show gap junction‐mediated oscillations in membrane potential that underlie their spike discharge (Logan et al , 1996, J Physiol), but the role of such coupling in vivo is uncertain. We made whole‐cell recordings from functionally identified SPN in the rat (aged p5‐16) working heart‐brainstem preparation (WHBP, (Paton, 1996, J Neurosci Meths)) to examine the neural mechanisms generating their firing activity. 108 SPNs identified in the T3‐4 segment were functionally categorised by responses to activation of peripheral chemoreflex (NaCN, ia) and diving response (cold to snout). Muscle vasoconstrictor (MVC, 38%) SPN were activated by both tests and converseley cutaneous vasoconstrictor (CVC, 27%) SPN were inhibited by both. MVCs had a higher baseline firing frequency in comparison with CVC (2.6±0.3 vs. 1.4±0.3 Hz; p =0.007) and shorter after‐hyperpolarization (156±10 vs. 296±39 ms, p =0.0001). MVC SPN showed a respiratory‐modulated pattern of firing generated by a torrent of kynurenate‐sensitive, excitatory synaptic inputs. By contrast, the activity of CVC SPN was driven by large, slow, biphasic membrane potential oscillations (n=14 of 15 examined) that resembled filtered action potentials which were relatively insensitive to membrane potential, not blocked by spinal kynurenate and were indistinguishable from those previously reported in vitro . Antidromic activation of CVC SPN evoked short latency depolarization confirming the presence of coupling. These findings indicate that gap junctional coupling plays an important functional role in the patterning and synchronization of the output from CVC but not MVC SPN. Funded by BHF.