title: Chronic Interactions Between Carotid Baroreceptors and Chemoreceptors in Obesity Hypertension.
abstract: Carotid bodies play a critical role in protecting against hypoxemia, and their activation increases sympathetic activity, arterial pressure, and ventilation, responses opposed by acute stimulation of the baroreflex. Although chemoreceptor hypersensitivity is associated with sympathetically mediated hypertension, the mechanisms involved and their significance in the pathogenesis of hypertension remain unclear. We investigated the chronic interactions of these reflexes in dogs with sympathetically mediated, obesity-induced hypertension based on the hypothesis that hypoxemia and tonic activation of carotid chemoreceptors may be associated with obesity. After 5 weeks on a high-fat diet, the animals experienced a 35% to 40% weight gain and increases in arterial pressure from 106±3 to 123±3 mm Hg and respiratory rate from 8±1 to 12±1 breaths/min along with hypoxemia (arterial partial pressure of oxygen=81±3 mm Hg) but eucapnia. During 7 days of carotid baroreflex activation by electric stimulation of the carotid sinus, tachypnea was attenuated, and hypertension was abolished before these variables returned to prestimulation values during a recovery period. After subsequent denervation of the carotid sinus region, respiratory rate decreased transiently in association with further sustained reductions in arterial partial pressure of oxygen (to 65±2 mm Hg) and substantial hypercapnia. Moreover, the severity of hypertension was attenuated from 125±2 to 116±3 mm Hg (45%-50% reduction). These findings suggest that hypoxemia may account for sustained stimulation of peripheral chemoreceptors in obesity and that this activation leads to compensatory increases in ventilation and central sympathetic outflow that contributes to neurogenically mediated hypertension. Furthermore, the excitatory effects of chemoreceptor hyperactivity are abolished by chronic activation of the carotid baroreflex.
authors.affiliation: From the Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson (T.E.L.); Department of Pharmacology (R.I.) and Department of Physiology (I.T.), University of Medicine and Pharmacy, "Gr. T. Popa," Iasi, Romania; Colonial Pipeline Company, Atlanta, GA (R.C.); CVRx, Inc., Minneapolis, MN (A.W.C., D.G.); and North Memorial Medical Center, Trauma Services, Robbinsdale, MN (E.D.I.).
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Lohmeier
authors.affiliation: From the Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson (T.E.L.); Department of Pharmacology (R.I.) and Department of Physiology (I.T.), University of Medicine and Pharmacy, "Gr. T. Popa," Iasi, Romania; Colonial Pipeline Company, Atlanta, GA (R.C.); CVRx, Inc., Minneapolis, MN (A.W.C., D.G.); and North Memorial Medical Center, Trauma Services, Robbinsdale, MN (E.D.I.).
authors.forename: Radu
authors.initials: R
authors.lastname: Iliescu
authors.affiliation: From the Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson (T.E.L.); Department of Pharmacology (R.I.) and Department of Physiology (I.T.), University of Medicine and Pharmacy, "Gr. T. Popa," Iasi, Romania; Colonial Pipeline Company, Atlanta, GA (R.C.); CVRx, Inc., Minneapolis, MN (A.W.C., D.G.); and North Memorial Medical Center, Trauma Services, Robbinsdale, MN (E.D.I.).
authors.forename: Ionut
authors.initials: I
authors.lastname: Tudorancea
authors.affiliation: From the Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson (T.E.L.); Department of Pharmacology (R.I.) and Department of Physiology (I.T.), University of Medicine and Pharmacy, "Gr. T. Popa," Iasi, Romania; Colonial Pipeline Company, Atlanta, GA (R.C.); CVRx, Inc., Minneapolis, MN (A.W.C., D.G.); and North Memorial Medical Center, Trauma Services, Robbinsdale, MN (E.D.I.).
authors.forename: Radu
authors.initials: R
authors.lastname: Cazan
authors.affiliation: From the Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson (T.E.L.); Department of Pharmacology (R.I.) and Department of Physiology (I.T.), University of Medicine and Pharmacy, "Gr. T. Popa," Iasi, Romania; Colonial Pipeline Company, Atlanta, GA (R.C.); CVRx, Inc., Minneapolis, MN (A.W.C., D.G.); and North Memorial Medical Center, Trauma Services, Robbinsdale, MN (E.D.I.).
authors.forename: Adam W
authors.initials: AW
authors.lastname: Cates
authors.affiliation: From the Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson (T.E.L.); Department of Pharmacology (R.I.) and Department of Physiology (I.T.), University of Medicine and Pharmacy, "Gr. T. Popa," Iasi, Romania; Colonial Pipeline Company, Atlanta, GA (R.C.); CVRx, Inc., Minneapolis, MN (A.W.C., D.G.); and North Memorial Medical Center, Trauma Services, Robbinsdale, MN (E.D.I.).
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Georgakopoulos
authors.affiliation: From the Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson (T.E.L.); Department of Pharmacology (R.I.) and Department of Physiology (I.T.), University of Medicine and Pharmacy, "Gr. T. Popa," Iasi, Romania; Colonial Pipeline Company, Atlanta, GA (R.C.); CVRx, Inc., Minneapolis, MN (A.W.C., D.G.); and North Memorial Medical Center, Trauma Services, Robbinsdale, MN (E.D.I.).
authors.forename: Eric D
authors.initials: ED
authors.lastname: Irwin
mesh_terms: D000818:Animals; D002344:Carotid Body; D002628:Chemoreceptor Cells / Q000378:metabolism; D059305:Diet, High-Fat / Q000009:adverse effects; D004195:Disease Models, Animal; D004285:Dogs; D004558:Electric Stimulation / Q000379:methods; D006973:Hypertension / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D011311:Pressoreceptors / Q000378:metabolism*; D011897:Random Allocation; D059246:Tachypnea / Q000209:etiology / Q000503:physiopathology*; D016896:Treatment Outcome
keywords: baroreflex; blood pressure; carotid bodies; hypertension; obesity; sympathetic nervous system