High-pass filtering of carotid-vagal influences on expiration in rat: role of N-methyl-D-aspartate receptors.
Repetitive electrical stimulation of the carotid sinus nerve or vagus nerve in rats elicited abrupt reflex shortening or prolongation, respectively, of the inter-burst interval of phrenic nerve activity followed by exponential decay from the initial response. Removal of the stimuli resulted in transient post-stimulus rebound excitation or inhibition that mirrored the corresponding stimulus-evoked responses. The biphasic responses to these complementary inputs approximate the on- and off-transients of full-wave differentiators or high-pass filters. Blockade of N-methyl-D-aspartate (NMDA) receptors abolished the post-stimulus rebounds and transformed both signal pathways 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-pass filtering effects may serve to increase the dynamic range and response speed of sensory neurotransmission to the brain, thereby enhancing closed-loop stability of sensorimotor reflex.
Poon
C S
CS
Harvard-MIT Division of Health Sciences and Technology, Rm E25-501, Massachusetts Institute of Technology, Cambridge, USA. cpoon@mit.edu
Young
D L
DL
Siniaia
M S
MS
D000818:Animals; D002346:Carotid Sinus / Q000187:drug effects / Q000294:innervation* / Q000502:physiology*; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D012125:Respiratory Center / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012143:Respiratory Physiological Phenomena / Q000187:drug effects*; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate