title: Reduced preprandial dipping accounts for rapid elevation of blood pressure and renal sympathetic nerve activity in rabbits fed a high-fat diet.
abstract: Consumption of a high-fat diet (HFD) by rabbits results in increased blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) within 1 wk. Here, we determined how early this activation occurred and whether it was related to changes in cardiovascular and neural 24-h rhythms. Rabbits were meal-fed a HFD for 3 wks, then a normal-fat diet (NFD) for 1 wk. BP, HR, and RSNA were measured daily in the home cage via implanted telemeters. Baseline BP, HR, and RSNA over 24 h were 71 ± 1 mm Hg, 205 ± 4 beats/min and 7 ± 1 normalized units (nu). The 24-h pattern was entrained to the feeding cycle and values increased from preprandial minimum to postprandial maximum by 4 ± 1 mm Hg, 51 ± 6 beats/min, and 1.6 ± .6 nu each day. Feeding of a HFD markedly diminished the preprandial dip after 2 d (79-125% of control; p < 0.05) and this reduction lasted for 3 wks of HFD. Twenty-four-hour BP, HR, and RSNA concurrently increased by 2%, 18%, and 22%, respectively. Loss of preprandial dipping accounted for all of the BP increase and 50% of the RSNA increase over 3 wks and the 24-h rhythm became entrained to the light-dark cycle. Resumption of a NFD did not alter the BP preprandial dip. Thus, elevated BP induced by a HFD and mediated by increased sympathetic nerve activity results from a reduction in preprandial dipping, from the first day. Increased calories, glucose, insulin, and leptin may account for early changes, whereas long-term loss of dipping may be related to increased sensitivity of sympathetic pathways.
authors.affiliation: Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Burke
authors.forename: Larissa J
authors.initials: LJ
authors.lastname: Prior
authors.forename: Elena V
authors.initials: EV
authors.lastname: Lukoshkova
authors.forename: Kyungjoon
authors.initials: K
authors.lastname: Lim
authors.forename: Benjamin
authors.initials: B
authors.lastname: Barzel
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Davern
authors.forename: James A
authors.initials: JA
authors.lastname: Armitage
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Head
mesh_terms: D000821:Animal Feed; D000818:Animals; D001794:Blood Pressure; D001835:Body Weight; D002940:Circadian Rhythm; D059305:Diet, High-Fat; D004041:Dietary Fats; D006339:Heart Rate; D006973:Hypertension / Q000503:physiopathology*; D007031:Hypothalamus / Q000502:physiology; D007668:Kidney / Q000294:innervation*; D008297:Male; D009765:Obesity / Q000150:complications; D011817:Rabbits; D013493:Suprachiasmatic Nucleus / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000502:physiology*; D013686:Telemetry / Q000379:methods
chemical_list: D004041:Dietary Fats