title: A central mechanism of acute baroreflex resetting in the conscious dog.
abstract: The role of the central nervous system in the mechanism(s) involved in acute carotid baroreflex resetting was studied in six conscious, chronically instrumented, aortic-denervated dogs. Dogs were prepared for reversible vascular isolation of the carotid sinuses. Acute baroreflex resetting was induced by holding the left carotid sinus pressure (LCcsp) at a given value for 20 minutes using a pulsatile pressure control system while at the same time keeping the right carotid sinus pressure (RCSP) at a subthreshold level (approximately 40 mm Hg). At the end of the 20 minutes, the LCcsp) was reduced to approximately 20 mm Hg, and a baroreflex (RCSP-mean arterial pressure [MAP]) curve was generated on the right carotid sinus using static-step increases in carotid sinus pressure. At the control LCcsp of 100 mm Hg, the RCSP-MAP baroreflex had a threshold pressure (Pth) of 86.6 +/- 3.1 mm Hg and a set point pressure (Psp) of 104.7 +/- 2.5 mm Hg. Increasing LCcsp) to 140 mm Hg for 20 minutes caused these parameters for the right carotid baroreflex to increase. Pth and Psp increased by 18.4 +/- 4.0 and 14.2 +/- 3.0 mm Hg, respectively (p less than 0.05). The baroreflex curve, therefore, was shifted upward and to the right. Decreasing LCcsp to 60 mm Hg caused Pth and Psp to decrease by 24.7 +/- 5.0 and 18.1 +/- 2 mm Hg, respectively (p less than 0.05). The baroreflex curve was therefore shift downward and to the left. The percent of resetting of Pth and Psp was 46 +/- 9% and 36 +/- 8%, respectively, when LCcsp was 140 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology and Biophysics, University of Nebraska College of Medicine, Omaha 68105.
authors.forename: W
authors.initials: W
authors.lastname: Tan
authors.forename: M J
authors.initials: MJ
authors.lastname: Panzenbeck
authors.forename: M A
authors.initials: MA
authors.lastname: Hajdu
authors.forename: I H
authors.initials: IH
authors.lastname: Zucker
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001794:Blood Pressure; D001921:Brain / Q000502:physiology*; D002346:Carotid Sinus / Q000502:physiology; D003243:Consciousness; D004285:Dogs; D011311:Pressoreceptors / Q000502:physiology*; D012018:Reflex / Q000502:physiology*