Cs. Poon et al., High-pass filtering of carotid-vagal influences on expiration in rat: roleof N-methyl-D-aspartate receptors, NEUROSCI L, 284(1-2), 2000, pp. 5-8
Repetitive electrical stimulation of the carotid sinus nerve or vagus nerve
in rats elicited abrupt reflex shortening or prolongation, respectively, o
f the inter-burst interval of phrenic nerve activity followed by exponentia
l decay from the initial response. Removal of the stimuli resulted in trans
ient post-stimulus rebound excitation or inhibition that mirrored the corre
sponding stimulus-evoked responses. The biphasic responses to these complem
entary inputs approximate the on- and off-transients of full-wave different
iators or high-pass filters. Blockade of N-methyl-D-aspartate (NMDA) recept
ors abolished the post-stimulus rebounds and transformed both signal pathwa
ys into integrators or low-pass filters, thus switching off part or all of
the high-pass filters. We suggest that such NMDA receptor-dependent high-pa
ss filtering effects may serve to increase the dynamic range and response s
peed of sensory neurotransmission to the brain, thereby enhancing closed-lo
op stability of sensorimotor reflex. (C) 2000 Elsevier Science Ireland Ltd.
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