title: Reduced carotid baroreceptor distensibility-induced baroreflex resetting contributes to impairment of sodium regulation in rats fed a high-fat diet.
abstract: Decreased carotid arterial compliance has been reported in obese subjects and animals. Carotid baroreceptors are located at the bifurcation of the common carotid artery, and respond to distension of the arterial wall, suggesting that higher pressure is required to obtain the same distension in obese subjects and animals. A hyperosmotic NaCl solution induces circulatory volume expansion and arterial pressure (AP) increase, which reflexively augment renal excretion. Thus, we hypothesized that sodium regulation via the baroreflex might be impaired in response to chronic hyperosmotic NaCl infusion in rats fed a high-fat diet. To examine this hypothesis, we used rats fed a high-fat (Fat) or normal (NFD) diet, and measured mean AP, water and sodium balance, and renal function in response to chronic infusion of hyperosmotic NaCl solution via a venous catheter. Furthermore, we examined arterial baroreflex characteristics with static open-loop analysis and distensibility of the common carotid artery. Significant positive water and sodium balance was observed on the 1st day of 9% NaCl infusion; however, this disappeared by the 2nd day in Fat rats. Mean AP was significantly higher during 9% NaCl infusion in Fat rats compared with NFD rats. In the open-loop analysis of carotid sinus baroreflex, a rightward shift of the neural arc was observed in Fat rats compared with NFD rats. Furthermore, distensibility of the common carotid artery was significantly reduced in Fat rats. These results indicate that a reduced baroreceptor distensibility-induced rightward shift of the neural arc might contribute to impairment of sodium regulation in Fat rats.
authors: Department of Physiology, Gifu University Graduate School of Medicine, Gifu, Japan;
authors: Chikara
authors: C
authors: Abe
authors: Department of Physiology, Gifu University Graduate School of Medicine, Gifu, Japan;
authors: Yuko
authors: Y
authors: Nagai
authors: Department of Physiology, Gifu University Graduate School of Medicine, Gifu, Japan;
authors: Aoi
authors: A
authors: Yamaguchi
authors: Department of Tissue and Organ Development, Regeneration, and Advanced Medical Science, Gifu University Graduate School of Medicine, Gifu, Japan;
authors: Hitomi
authors: H
authors: Aoki
authors: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and.
authors: Shuji
authors: S
authors: Shimizu
authors: Department of Cardiac Physiology, National Cerebral and Cardiovascular Center, Osaka, Japan.
authors: Tsuyoshi
authors: T
authors: Akiyama
authors: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and.
authors: Toru
authors: T
authors: Kawada
authors: Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and.
authors: Masaru
authors: M
authors: Sugimachi
authors: Department of Physiology, Gifu University Graduate School of Medicine, Gifu, Japan; zunzunmorita@gmail.com.
authors: Hironobu
authors: H
authors: Morita
mesh_terms: D000818:Animals; D017704:Baroreflex; D001794:Blood Pressure; D002344:Carotid Body / Q000166:cytology / Q000502:physiology*; D059305:Diet, High-Fat / Q000009:adverse effects*; D008297:Male; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000097:blood* / Q000494:pharmacology
chemical_list: D012964:Sodium
keywords: arterial pressure; high-fat diet; renal function; renal sympathetic nerve activity; sodium excretion