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Effects of exercise training on SFO-mediated sympathoexcitation during chronic heart failure.

ABSTRACT: Exercise training (ExT) has been shown to reduce sympathetic drive during heart failure (HF). The subfornical organ (SFO) is involved in the neural control of sympathetic drive. We hypothesized that an activated SFO contributes to enhanced sympathetic activity in HF. We also postulated that ExT would reduce the activation of the SFO and its contribution to the sympathetic drive during HF. Sprague-Dawley rats were subjected to coronary artery ligation to induce HF. Rats were assigned to ExT for 3-4 wk. Rats with HF had a 2.5-fold increase in FosB-positive cells in the SFO compared with sham-operated rats, and this was normalized by ExT. Microinjection of ANG II (100 pmol) into the SFO resulted in a greater increase in renal sympathetic nerve activity (RSNA), blood pressure, and heart rate in the HF group than in the sham-operated group. These responses were normalized after ExT (change in RSNA: 23 ± 3% vs. 8 ± 2%). ExT also abolished the decrease in RSNA in HF rats after the microinjection of losartan (200 pmol) into the SFO (-21 ± 4% vs. -2 ± 3%). Finally, there was elevated mRNA (5-fold) and protein expression (43%) of ANG II type 1 receptors in the SFO of rats with HF, which were reversed after ExT. These data suggest that the enhanced activity of the SFO by elevated tonic ANG II contributes to the enhanced sympathoexcitation exhibited in HF. The decrease in ANG II type 1 receptor expression in the SFO by ExT may be responsible for reversing the neuronal activation in the SFO and SFO-mediated sympathoexcitation in rats with HF.

SUBMITTER: Llewellyn TL

PROVIDER: S-EPMC3920154 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature

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Effects of exercise training on SFO-mediated sympathoexcitation during chronic heart failure.

Llewellyn Tamra L TL Sharma Neeru M NM Zheng Hong H Patel Kaushik P KP

American journal of physiology. Heart and circulatory physiology 20131025 1

Exercise training (ExT) has been shown to reduce sympathetic drive during heart failure (HF). The subfornical organ (SFO) is involved in the neural control of sympathetic drive. We hypothesized that an activated SFO contributes to enhanced sympathetic activity in HF. We also postulated that ExT would reduce the activation of the SFO and its contribution to the sympathetic drive during HF. Sprague-Dawley rats were subjected to coronary artery ligation to induce HF. Rats were assigned to ExT for 3 ...[more]

PMID: 24163080

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Project description:BackgroundThe safety and efficacy of aerobic exercise in heart failure (HF) patients with atrial fibrillation (AF) has not been well evaluated.ObjectivesThis study examined whether outcomes with exercise training in HF vary according to AF status.MethodsHF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training) randomized 2,331 ambulatory HF patients with ejection fraction ≤35% to exercise training or usual care. We examined clinical characteristics and outcomes (mortality/hospitalization) by baseline AF status (past history of AF or AF on baseline electrocardiogram vs. no AF) using adjusted Cox models and explored an interaction with exercise training. We assessed post-randomization AF events diagnosed via hospitalizations for AF and reports of serious arrhythmia caused by AF.ResultsOf 2,292 patients with baseline rhythm data, 382 (17%) had AF, 1,602 (70%) had sinus rhythm, and 308 (13%) had "other" rhythm. Patients with AF were older and had lower peak Vo2. Over a median follow-up of 2.6 years, AF was associated with a 24% per year higher rate of mortality/hospitalization (hazard ratio [HR]: 1.53; 95% confidence interval [CI]: 1.34 to 1.74; p < 0.001) in unadjusted analysis; this did not remain significant after adjustment (HR: 1.15; 95% CI: 0.98 to 1.35; p = 0.09). There was no significant difference in AF event rates by randomized treatment assignment in the overall population or by baseline AF status (all p > 0.10). There was no interaction between AF and exercise training on measures of functional status or clinical outcomes (all p > 0.10).ConclusionsAF in patients with chronic HF was associated with older age, reduced exercise capacity at baseline, and a higher overall rate of clinical events, but not a differential response to exercise training for clinical outcomes or changes in exercise capacity. (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training [HF-ACTION]; NCT00047437).

Project description:Depression is common in patients with cardiac disease, especially in patients with heart failure, and is associated with increased risk of adverse health outcomes. Some evidence suggests that aerobic exercise may reduce depressive symptoms, but to our knowledge the effects of exercise on depression in patients with heart failure have not been evaluated.To determine whether exercise training will result in greater improvements in depressive symptoms compared with usual care among patients with heart failure.Multicenter, randomized controlled trial involving 2322 stable patients treated for heart failure at 82 medical clinical centers in the United States, Canada, and France. Patients who had a left ventricular ejection fraction of 35% or lower, had New York Heart Association class I to IV heart failure, and had completed the Beck Depression Inventory II (BDI-II) score were randomized (1:1) between April 2003 and February 2007. Depressive scores ranged from 0 to 59; scores of 14 or higher are considered clinically significant.Participants were randomized either to supervised aerobic exercise (goal of 90 min/wk for months 1-3 followed by home exercise with a goal of ?120 min/wk for months 4-12) or to education and usual guideline-based heart failure care.Composite of death or hospitalization due to any cause and scores on the BDI-II at months 3 and 12.Over a median follow-up period of 30 months, 789 patients (68%) died or were hospitalized in the usual care group compared with 759 (66%) in the aerobic exercise group (hazard ratio [HR], 0.89; 95% CI, 0.81 to 0.99; P = .03). The median BDI-II score at study entry was 8, with 28% of the sample having BDI-II scores of 14 or higher. Compared with usual care, aerobic exercise resulted in lower mean BDI-II scores at 3 months (aerobic exercise, 8.95; 95% CI, 8.61 to 9.29 vs usual care, 9.70; 95% CI, 9.34 to 10.06; difference, -0.76; 95% CI,-1.22 to -0.29; P = .002) and at 12 months (aerobic exercise, 8.86; 95% CI, 8.67 to 9.24 vs usual care, 9.54; 95% CI, 9.15 to 9.92; difference, -0.68; 95% CI, -1.20 to -0.16; P = .01).Compared with guideline-based usual care, exercise training resulted in a modest reduction in depressive symptoms, although the clinical significance of this improvement is unknown.clinicaltrials.gov Identifier: NCT00047437.

Project description:Findings from previous studies of the effects of exercise training on patient-reported health status have been inconsistent.To test the effects of exercise training on health status among patients with heart failure.Multicenter, randomized controlled trial among 2331 medically stable outpatients with heart failure with left ventricular ejection fraction of 35% or less. Patients were randomized from April 2003 through February 2007.Usual care plus aerobic exercise training (n = 1172), consisting of 36 supervised sessions followed by home-based training, vs usual care alone (n = 1159). Randomization was stratified by heart failure etiology, which was a covariate in all models.Kansas City Cardiomyopathy Questionnaire (KCCQ) overall summary scale and key subscales at baseline, every 3 months for 12 months, and annually thereafter for up to 4 years. The KCCQ is scored from 0 to 100 with higher scores corresponding to better health status. Treatment group effects were estimated using linear mixed models according to the intention-to-treat principle.Median follow-up was 2.5 years. At 3 months, usual care plus exercise training led to greater improvement in the KCCQ overall summary score (mean, 5.21; 95% confidence interval, 4.42 to 6.00) compared with usual care alone (3.28; 95% confidence interval, 2.48 to 4.09). The additional 1.93-point increase (95% confidence interval, 0.84 to 3.01) in the exercise training group was statistically significant (P < .001). After 3 months, there were no further significant changes in KCCQ score for either group (P = .85 for the difference between slopes), resulting in a sustained, greater improvement overall for the exercise group (P < .001). Results were similar on the KCCQ subscales, and no subgroup interactions were detected.Exercise training conferred modest but statistically significant improvements in self-reported health status compared with usual care without training. Improvements occurred early and persisted over time.clinicaltrials.gov Identifier: NCT00047437.

Dataset Information

Effects of exercise training on SFO-mediated sympathoexcitation during chronic heart failure.

Publications

Effects of exercise training on SFO-mediated sympathoexcitation during chronic heart failure.

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