State influences on ventral medullary surface and physiological responses to sodium cyanide challenges.
Intravenous sodium cyanide (NaCN) administration lowers ventral medullary surface (VMS) activity in anesthetized cats. Sleep states modify spontaneous and blood pressure-evoked VMS activity and may alter VMS responses to chemoreceptor input. We studied VMS activation during peripheral chemoreceptor stimulation by intravenous NaCN using optical procedures in six cats instrumented for recording sleep physiology during sham saline and control site trials. Images of scattered 660-nm light were collected at 50 frames/s with an optical device after 80-100 microg total bolus intravenous NaCN delivery during waking and sleep states. Cyanide elicited an initial ventilatory decline, followed by large inspiratory efforts and an increase in respiratory rate, except in rapid eye movement sleep, in which an initial breathing increase occurred. NaCN evoked a pronounced decrease in VMS activity in all states; control sites and sham injections showed little effect. The activity decline was faster in rapid eye movement sleep, and the activity nadir occurred later in waking. Sleep states alter the time course but not the extent of decline in VMS activity.
Macey
P M
PM
Department of Neurobiology and the Brain Research Institute, University of California at Los Angeles, Los Angeles, 90095-1763, California, USA.
Richard
C A
CA
Rector
D M
DM
Harper
R K
RK
Harper
R M
RM
D000818:Animals; D001143:Arousal / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002344:Carotid Body / Q000187:drug effects / Q000502:physiology; D002415:Cats; D002628:Chemoreceptor Cells / Q000187:drug effects* / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006339:Heart Rate / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D008526:Medulla Oblongata / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D055096:Optical Devices; D055095:Optics and Photonics; D012119:Respiration; D012125:Respiratory Center / Q000166:cytology / Q000502:physiology; D012895:Sleep, REM / Q000502:physiology; D012966:Sodium Cyanide / Q000494:pharmacology*; D013268:Stimulation, Chemical
D004791:Enzyme Inhibitors; D012966:Sodium Cyanide