Loss of Diurnal Rhythms of Blood Pressure and Heart Rate Due to High Fat Feeding

The majority of patients with obesity, insulin resistance, and metabolic syndrome have hypertension, but the mechanisms of hypertension are poorly understood. In these patients, impaired sodium excretion is critical for the genesis of Na+-sensitive hypertension, and prior studies have proposed a role for the epithelial Na+ channel (ENaC) in this syndrome. We characterized high fat-fed mice as a model in which to study the contribution of ENaC-mediated Na+ reabsorption in obesity and insulin resistance. High fat-fed mice demonstrated impaired Na+ excretion and elevated blood pressure, which was significantly higher on a high-Na+ diet compared with low fat-fed control mice. However, high fat-fed mice had no increase in ENaC activity as measured by Na+ transport across microperfused cortical collecting ducts, electrolyte excretion, or blood pressure. In addition, we found no difference in endogenous urinary aldosterone excretion between groups on a normal or high-Na+ diet. High fat-fed mice provide a model of metabolic syndrome, recapitulating obesity, insulin resistance, impaired natriuresis, and a Na+-sensitive elevation in blood pressure. Surprisingly, in contrast to previous studies, our data demonstrate that high fat feeding of mice impairs natriuresis and produces elevated blood pressure that is independent of ENaC activity and likely caused by increased Na+ reabsorption upstream of the aldosterone-sensitive distal nephron.

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Abstract 477: Chronic Baroreflex Activation Improves Baroreflex Control of Heart Rate In Obesity

Hypertension ◽

10.1161/hyp.60.suppl_1.a477 ◽

2012 ◽

Vol 60 (suppl_1) ◽

Author(s):

Radu Iliescu ◽

Ionut Tudorancea ◽

Eric Irwin ◽

Thomas Lohmeier

Keyword(s):

Heart Rate ◽

Pulse Interval ◽

Vagal Activity ◽

Fat Intake ◽

High Fat ◽

Baroreflex Control ◽

Systolic Blood Pressure Variability ◽

Body Weight Increase ◽

Obesity Hypertension ◽

Fat Feeding

Impaired baroreflex control of heart rate (BRS) and attendant risk for cardiac arrhythmias are associated with sympathetically-mediated obesity hypertension. Since both global and renal-specific sympathoinhibition have sustained antihypertensive effects in obesity, we compared BRS in obese dogs subjected to 7 days of electrical baroreflex activation (BA) and, after recovery (REC), to bilateral surgical renal denervation (RDX). After control (C) measurements and 4 weeks of high fat diet, fat intake was reduced (RF) to maintain a body weight increase of ∼ 50%, which led to an increase in mean arterial pressure (MAP) from 100±2 to 117±3 mmHg and heart rate (HR) from 86±3 to 130±4 bpm. Obesity hypertension was associated with decreased sensitivity of 24h spontaneous BRS (determined by the sequence technique from daily beat-to-beat time series) and pulse interval (PI) variability (24h SD). While both BA and RDX abolished hypertension, only BA diminished tachycardia and normalized BRS, consequently improving HR variability. Short-term systolic blood pressure variability (5 min SD) also decreased with high fat feeding and was restored to control upon reduction of fat intake (RF) during established obesity hypertension, suggesting a vasoplegic effect of fat. These data suggest that in addition to the antihypertensive effects of sympathoinhibition, BA corrects cardiac baroreflex dysfunction in obesity hypertension, presumably by enhancing cardiac vagal activity. This in turn markedly improves depressed HR variability, a known risk factor for cardiac arrhythmic events.

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Changes in short-term variability of blood pressure and heart rate during the development of obesity-associated hypertension in high-fat fed dogs

Journal of Hypertension ◽

10.1097/00004872-199917080-00013 ◽

1999 ◽

Vol 17 (8) ◽

pp. 1135-1143 ◽

Cited By ~ 48

Author(s):

P Verwaerde ◽

J M. Sénard ◽

M Galinier ◽

P Rougé ◽

P Massabuau ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

High Fat ◽

Short Term ◽

Short Term Variability

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Diurnal rhythms of blood pressure, heart rate, and locomotor activity in adult and old male Wistar rats

Physiology & Behavior ◽

10.1016/s0031-9384(00)00276-6 ◽

2000 ◽

Vol 70 (3-4) ◽

pp. 375-380 ◽

Cited By ~ 22

Author(s):

B Zhang

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Locomotor Activity ◽

Wistar Rats ◽

Diurnal Rhythms ◽

Male Wistar Rats

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Blood Pressure, Heart Rate and Neuroendocrine Responses to a High Carbohydrate and a High Fat Meal in Healthy Young Subjects

Clinical Science ◽

10.1042/cs0790517 ◽

1990 ◽

Vol 79 (5) ◽

pp. 517-522 ◽

Cited By ~ 51

Author(s):

D. Heseltine ◽

J. F. Potter ◽

G. Hartley ◽

I. A. MacDonald ◽

O. F. W. James

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Plasma Insulin ◽

The Elderly ◽

High Fat ◽

High Carbohydrate ◽

Neuroendocrine Responses ◽

Young Subjects ◽

Fat Meal ◽

Carbohydrate Meal

1. The responses of blood pressure, heart rate, autonomic function and plasma insulin to a high carbohydrate and a high fat meal of equivalent energy value were studied in nine young volunteers. 2. Neither meal produced a significant change in supine or erect blood pressure. The high carbohydrate meal, however, resulted in an overall rise in both supine (6 beats/min) and erect (6 beats/min; P < 0.05) heart rate, no such changes being seen after the high fat meal. 3. Plasma noradrenaline levels increased by a maximum of 126% at 90 min (0.98 to 2.22 nmol/l) after the high carbohydrate meal but were virtually unchanged after the high fat meal (P < 0.01). Parasympathetic function showed no between-meal differences. Plasma insulin and glucose levels were significantly higher after the high carbohydrate meal than after the high fat meal. No postprandial difference in packed cell volume was found between meal types. 4. We conclude that, in young subjects, the postprandial blood pressure after a high carbohydrate meal is maintained by an increase in heart rate associated with increased sympathetic nervous system activity. These changes are at variance with the blood pressure and heart rate responses seen in the elderly after a high carbohydrate meal. A high fat meal has no significant cardiovascular or neuroendocrine effects in the young or old. The nutrient composition of meals has to be taken into account when studying the postprandial cardiovascular and neuroendocrine responses in the young.

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Measurement of blood pressure and heart rate by telemetry in conscious, unrestrained marmosets

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.264.5.h1509 ◽

1993 ◽

Vol 264 (5) ◽

pp. H1509-H1516 ◽

Cited By ~ 2

Author(s):

C. R. Schnell ◽

J. M. Wood

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Enzyme Inhibitor ◽

Diurnal Rhythms ◽

Prolonged Treatment ◽

Accurate Information ◽

Low Sodium Diet ◽

Pressure Lowering ◽

Duration Of Response ◽

Drug Treatments

A system is described for the continuous measurement of blood pressure, heart rate, and motor activity by telemetry in conscious marmosets freely moving in their home cages. Consistent diurnal variations in these parameters were observed under standard conditions, although these parameters were sensitive to changes in the environment. Blood pressure values were similar to those measured by nontelemetric methods in conscious, restrained marmosets. However, heart rate was lower, indicating that telemetry is less stressful. The suitability of this system for assessing the effects of blood pressure-lowering drugs was evaluated. An acute or a prolonged treatment with a converting enzyme inhibitor of marmosets maintained on a low-sodium diet induced a fall in blood pressure as previously observed using nontelemetric methods. With telemetry, however, more accurate information on the duration of response and the effects of the treatment on the diurnal rhythms was obtained. These observations demonstrate the advantages of telemetry for evaluating the hemodynamic effects of drug treatments under physiological conditions.

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Effects of Meal Composition on the Postprandial Blood Pressure, Catecholamine and Insulin Changes in Elderly Subjects

Clinical Science ◽

10.1042/cs0770265 ◽

1989 ◽

Vol 77 (3) ◽

pp. 265-272 ◽

Cited By ~ 68

Author(s):

J. F. Potter ◽

D. Heseltine ◽

G. Hartley ◽

J. Matthews ◽

I. A. Macdonald ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Cell Volume ◽

Packed Cell Volume ◽

Plasma Insulin ◽

Autonomic Function ◽

High Protein ◽

Elderly Subjects ◽

High Fat ◽

High Carbohydrate

1. The effects of four meals of similar energy, but different nutritional, composition on postprandial blood pressure, heart rate, autonomic function, catecholamines, insulin and packed cell volume levels were studied in seven fit elderly subjects. 2. The high carbohydrate and high protein meals led to a significant overall fall in supine systolic and diastolic blood pressure compared either with no change or a rise after the normal (i.e. mixed) and high fat meals. Similar between-meal differences were seen with erect diastolic but not erect systolic blood pressure. No significant postural blood pressure fall occurred after any of the meals. Supine heart rate was unaffected by meal type or by time, and although erect heart rate showed a small increase during the study there was no between-meal difference. 3. Parasympathetic function was unaffected by meal type. Plasma noradrenaline rose after the high carbohydrate and mixed meals only, remaining elevated for 120 min after meal consumption. This increase was not related to the changes in blood pressure or plasma insulin levels. 4. Plasma insulin and glucose rose after the high carbohydrate and mixed meals, but were unchanged after the high protein and high fat meals. Packed cell volume showed a small decrease towards the end of the study, although there was no between-meal variation. 5. The differences in the cardiovascular changes after the different meals could not be ascribed to alterations in autonomic function, insulin release or fall in plasma volume. We propose that the postprandial changes in blood pressure are due to the nutrient composition of the meal rather than the actual energy load.

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The hypotensive response to oral fat is comparable but slower compared with carbohydrate in healthy elderly subjects

British Journal Of Nutrition ◽

10.1079/bjn20051633 ◽

2006 ◽

Vol 95 (2) ◽

pp. 340-345 ◽

Cited By ~ 17

Author(s):

Renuka Visvanathan ◽

Michael Horowitz ◽

Ian Chapman

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Area Under The Curve ◽

Elderly Subjects ◽

High Fat ◽

Postprandial Hypotension ◽

Healthy Elderly ◽

Hypotensive Response ◽

Healthy Elderly Subjects

The objective of the present study was to determine the comparative hypotensive responses to drinks containing predominantly fat and carbohydrate (CHO) in healthy elderly subjects. Using a randomised, cross-over study, the participants, twelve elderly subjects, six of them female (72·2 (sd 5·7) years), were investigated. On three separate days, blood pressure (BP) and heart rate were measured following ingestion of 300ml drinks containing: (1) CHO (75g glucose and 93g Polyjoule (CHO polymer) providing 2732kJ (653kcal)); (2) 88% fat (cream blended with milk providing 2732kJ (653kcal)); (3) water. Systolic BP decreased following the CHO drink (P<0·001) and the high-fat drink (P<0·001) but not water; there was no difference in the magnitude of the decrease between the CHO drink and the drink containing fat (13·4v. 15·6mmHg). However, the onset of the fall was slower after the fat-containing drink (13·0v. 26·5min (P=0·01); area under the curve for 0–30min for CHO drink −6·5v. fat-containing drink 125·4 mmHg×min (P=0·043)). We conclude that ingestion of a high-fat drink results in a comparable fall in BP to a CHO drink although the onset is relatively slower. These observations may have implications for the management of postprandial hypotension.

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