title: Rodent cardiovascular responses to baroreceptor unloading: effect of plane of anaesthesia.
abstract: The objective of this study was to determine whether a plane of urethane-α-chloralose anaesthesia that suppresses motor reflexes would affect baroreflex cardiovascular control relative to a plane of anaesthesia that leaves motor reflexes intact. Adult male Sprague-Dawley rats were anaesthetized to either a light (motor reflexes intact) or deep (motor reflexes suppressed) plane of anaesthesia. Animals were exposed to graded (-2 to -10 mm Hg) lower body negative pressure while heart rate, vascular resistance, and mean arterial pressure were assessed. No between-group differences were observed in baseline hemodynamics. Graded lower body negative pressure progressively increased heart rate (p < 0.01) and vascular resistance (p < 0.001) and reduced mean arterial pressure (p < 0.001) similarly in light and deep planes of anaesthesia. Therefore, the deep plane of anaesthesia was not associated with a degradation of the autonomic response to baroreceptor unloading beyond that observed at the light plane. These data support the use of urethane-α-chloralose anaesthesia in studies examining reflex cardiovascular control concomitant with some degree of noxious stimulation.
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, The University of Western Ontario, London, ON, Canada.
authors.forename: Charlotte W
authors.initials: CW
authors.lastname: Usselman
authors.forename: Louis
authors.initials: L
authors.lastname: Mattar
authors.forename: Jasna
authors.initials: J
authors.lastname: Twynstra
authors.forename: Ian
authors.initials: I
authors.lastname: Welch
authors.forename: J Kevin
authors.initials: JK
authors.lastname: Shoemaker
mesh_terms: D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D008150:Lower Body Negative Pressure; D008297:Male; D011311:Pressoreceptors / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley