Spontaneous baroreflex control of heart rate during exercise and muscle metaboreflex activation in heart failure

2007 ◽  
Vol 293 (3) ◽  
pp. H1929-H1936 ◽  
Author(s):  
Ferdinando Iellamo ◽  
Javier A. Sala-Mercado ◽  
Masashi Ichinose ◽  
Robert L. Hammond ◽  
Marco Pallante ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Baroreflex Sensitivity ◽  
Left Ventricular ◽  
Dynamic Exercise ◽  
Response Relationship ◽  
Baroreflex Control ◽  
Muscle Metaboreflex ◽  
Stimulus Response ◽  
Spontaneous Baroreflex

In heart failure (HF), there is a reduced baroreflex sensitivity at rest, and during dynamic exercise there is enhanced muscle metaboreflex activation (MRA). However, how the arterial baroreflex modulates HR during exercise is unknown. We tested the hypothesis that spontaneous baroreflex sensitivity (SBRS) is attenuated during exercise in HF and that MRA further depresses SBRS. In seven conscious dogs we measured heart rate (HR), cardiac output, and left ventricular systolic pressure at rest and during mild and moderate dynamic exercise, before and during MRA (via imposed reductions of hindlimb blood flow), and before and after induction of HF (by rapid ventricular pacing). SBRS was assessed by the sequences method. In control, SBRS was reduced from rest with a progressive resetting of the baroreflex stimulus-response relationship in proportion to exercise intensity and magnitude of MRA. In HF, SBRS was significantly depressed in all settings; however, the changes with exercise and MRA occurred with a pattern similar to the control state. As in control, the baroreflex stimulus-response relationship showed an intensity- and muscle metaboreflex (MMR)-dependent rightward and upward shift. The results of this study indicate that HF induces an impairment in baroreflex control of HR at rest and during exercise, although the effects of exercise and MRA on SBRS occur with a similar pattern as in control, indicating the persistence of some vagal activity.

Spontaneous baroreflex control of cardiac output during dynamic exercise, muscle metaboreflex activation, and heart failure

2008 ◽  
Vol 294 (3) ◽  
pp. H1310-H1316 ◽  
Author(s):  
Masashi Ichinose ◽  
Javier A. Sala-Mercado ◽  
Donal S. O'Leary ◽  
Robert L. Hammond ◽  
Matthew Coutsos ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Output ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Dynamic Exercise ◽  
Baroreflex Control ◽  
Ventricular Systolic Pressure ◽  
Muscle Metaboreflex ◽  
Before And After ◽  
Spontaneous Baroreflex

We have previously shown that spontaneous baroreflex-induced changes in heart rate (HR) do not always translate into changes in cardiac output (CO) at rest. We have also shown that heart failure (HF) decreases this linkage between changes in HR and CO. Whether dynamic exercise and muscle metaboreflex activation (via imposed reductions in hindlimb blood flow) further alter this translation in normal and HF conditions is unknown. We examined these questions using conscious, chronically instrumented dogs before and after pacing-induced HF during mild and moderate dynamic exercise with and without muscle metaboreflex activation. We measured left ventricular systolic pressure (LVSP), CO, and HR and analyzed the spontaneous HR-LVSP and CO-LVSP relationships. In normal animals, mild exercise significantly decreased HR-LVSP (−3.08 ± 0.5 vs. −5.14 ± 0.6 beats·min−1·mmHg−1; P < 0.05) and CO-LVSP (−134.74 ± 24.5 vs. −208.6 ± 22.2 ml·min−1·mmHg−1; P < 0.05). Moderate exercise further decreased both and, in addition, significantly reduced HR-CO translation (25.9 ± 2.8% vs. 52.3 ± 4.2%; P < 0.05). Muscle metaboreflex activation at both workloads decreased HR-LVSP, whereas it had no significant effect on CO-LVSP and the HR-CO translation. HF significantly decreased HR-LVSP, CO-LVSP, and the HR-CO translation in all situations. We conclude that spontaneous baroreflex HR responses do not always cause changes in CO during exercise. Moreover, muscle metaboreflex activation during mild and moderate dynamic exercise reduces this coupling. In addition, in HF the HR-CO translation also significantly decreases during both workloads and decreases even further with muscle metaboreflex activation.

scholarly journals Progressive muscle metaboreflex activation gradually decreases spontaneous heart rate baroreflex sensitivity during dynamic exercise

2010 ◽  
Vol 298 (2) ◽  
pp. H594-H600 ◽  
Author(s):  
Javier A. Sala-Mercado ◽  
Masashi Ichinose ◽  
Matthew Coutsos ◽  
Zhenhua Li ◽  
Dominic Fano ◽  
...  
Keyword(s):  
Heart Rate ◽  
Baroreflex Sensitivity ◽  
Pressor Response ◽  
Substantial Reduction ◽  
Systolic Arterial Pressure ◽  
Left Ventricular ◽  
Dynamic Exercise ◽  
Baroreflex Control ◽  
Muscle Metaboreflex ◽  
Linear Relationships

Ischemia of active skeletal muscle elicits a pressor response termed the muscle metaboreflex. We tested the hypothesis that in normal dogs during dynamic exercise, graded muscle metaboreflex activation (MMA) would progressively attenuate spontaneous heart rate baroreflex sensitivity (SBRS). The animals were chronically instrumented to measure heart rate (HR), cardiac output (CO), mean and systolic arterial pressure (MAP and SAP), and left ventricular systolic pressures (LVSP) at rest and during mild or moderate treadmill exercise before and during progressive MMA [via graded reductions of hindlimb blood flow (HLBF)]. SBRS [slopes of the linear relationships (LRs) between HR and LVSP or SAP during spontaneous sequences of ≥3 consecutive beats when HR changed inversely vs. pressure] decreased during mild exercise from the resting values (−5.56 ± 0.86 vs. −2.67 ± 0.50 beats·min−1·mmHg−1, P <0.05), and in addition, these LRs were shifted upward. Progressive MMA gradually and linearly increased MAP, CO, and HR; linearly decreased SBRS; and shifted LRs upward and rightward to higher HR and pressures denoting baroreflex resetting. Moderate exercise caused a substantial reduction in SBRS (−1.57 ± 0.38 beats·min−1·mmHg−1, P <0.05) and both an upward and rightward resetting. Gradual MMA at this higher workload also caused significant progressive increases in MAP, CO, and HR and progressive decreases in SBRS, and the LRs were shifted to higher MAP and HR. Our results demonstrate that gradual MMA during mild and moderate dynamic exercise progressively decreases SBRS. In addition, baroreflex control of HR is progressively reset to higher blood pressure and HR in proportion to the extent of MMA.

Muscle metaboreflex attenuates spontaneous heart rate baroreflex sensitivity during dynamic exercise

2007 ◽  
Vol 292 (6) ◽  
pp. H2867-H2873 ◽  
Author(s):  
Javier A. Sala-Mercado ◽  
Masashi Ichinose ◽  
Robert L. Hammond ◽  
Tomoko Ichinose ◽  
Marco Pallante ◽  
...  
Keyword(s):  
Heart Rate ◽  
Exercise Intensity ◽  
Baroreflex Sensitivity ◽  
Pressor Response ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Dynamic Exercise ◽  
Moderate Exercise ◽  
Ventricular Systolic Pressure ◽  
Muscle Metaboreflex

Hypoperfusion of active skeletal muscle elicits a reflex pressor response termed the muscle metaboreflex. Dynamic exercise attenuates spontaneous baroreflex sensitivity (SBRS) in the control of heart rate (HR) during rapid, spontaneous changes in blood pressure (BP). Our objective was to determine whether muscle metaboreflex activation (MRA) further diminishes SBRS. Conscious dogs were chronically instrumented for measurement of HR, cardiac output, mean arterial pressure, and left ventricular systolic pressure (LVSP) at rest and during mild (3.2 km/h) or moderate (6.4 km/h at 10% grade) dynamic exercise before and after MRA (via partial reduction of hindlimb blood flow). SBRS was evaluated as the slopes of the linear relations (LRs) between HR and LVSP during spontaneous sequences of at least three consecutive beats when HR changed inversely vs. pressure (expressed as beats·min−1·mmHg−1). During mild exercise, these LRs shifted upward, with a significant decrease in SBRS (−3.0 ± 0.4 vs. −5.2 ± 0.4, P < 0.05 vs. rest). MRA shifted LRs upward and rightward and decreased SBRS (−2.1 ± 0.1, P < 0.05 vs. mild exercise). Moderate exercise shifted LRs upward and rightward and significantly decreased SBRS (−1.2 ± 0.1, P < 0.05 vs. rest). MRA elicited further upward and rightward shifts of the LRs and reductions in SBRS (−0.9 ± 0.1, P < 0.05 vs. moderate exercise). We conclude that dynamic exercise resets the arterial baroreflex to higher BP and HR as exercise intensity increases. In addition, increases in exercise intensity, as well as MRA, attenuate SBRS.

scholarly journals Dynamic cardiac output regulation at rest, during exercise, and muscle metaboreflex activation: impact of congestive heart failure

2012 ◽  
Vol 303 (7) ◽  
pp. R757-R768 ◽  
Author(s):  
Masashi Ichinose ◽  
Javier A. Sala-Mercado ◽  
Matthew Coutsos ◽  
ZhenHua Li ◽  
Tomoko K. Ichinose ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Output ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Dynamic Exercise ◽  
Moderate Exercise ◽  
Baroreflex Control ◽  
Ventricular Systolic Pressure ◽  
Muscle Metaboreflex ◽  
High Level

We tested whether mild and moderate dynamic exercise and muscle metaboreflex activation (MMA) affect dynamic baroreflex control of heart rate (HR) and cardiac output (CO), and the influence of stroke volume (SV) fluctuations on CO regulation in normal (N) and pacing-induced heart failure (HF) dogs by employing transfer function analyses of the relationships between spontaneous changes in left ventricular systolic pressure (LVSP) and HR, LVSP and CO, HR and CO, and SV and CO at low and high frequencies (Lo-F, 0.04–0.15 Hz; Hi-F, 0.15–0.6 Hz). In N dogs, both workloads significantly decreased the gains for LVSP-HR and LVSP-CO in Hi-F, whereas only moderate exercise also reduced the LVSP-CO gain in Lo-F. MMA during mild exercise further decreased the gains for LVSP-HR in both frequencies and for LVSP-CO in Lo-F. MMA during moderate exercise further reduced LVSP-HR gain in Lo-F. Coherence for HR-CO in Hi-F was decreased by exercise and MMA, whereas that in Lo-F was sustained at a high level (>0.8) in all settings. HF significantly decreased dynamic HR and CO regulation in all situations. In HF, the coherence for HR-CO in Lo-F decreased significantly in all settings; the coherence for SV-CO in Lo-F was significantly higher. We conclude that dynamic exercise and MMA reduces dynamic baroreflex control of HR and CO, and these are substantially impaired in HF. In N conditions, HR modulation plays a major role in CO regulation. In HF, influence of HR modulation wanes, and fluctuations of SV dominate in CO variations.

scholarly journals Muscle metaboreflex-induced increases in effective arterial elastance: effect of heart failure

2020 ◽  
Vol 319 (1) ◽  
pp. R1-R10 ◽  
Author(s):  
Joseph Mannozzi ◽  
Jasdeep Kaur ◽  
Marty D. Spranger ◽  
Mohamed-Hussein Al-Hassan ◽  
Beruk Lessanework ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Dynamic Exercise ◽  
Stroke Work ◽  
Arterial Elastance ◽  
Muscle Metaboreflex ◽  
Effective Arterial Elastance

Dynamic exercise elicits robust increases in sympathetic activity in part due to muscle metaboreflex activation (MMA), a pressor response triggered by activation of skeletal muscle afferents. MMA during dynamic exercise increases arterial pressure by increasing cardiac output via increases in heart rate, ventricular contractility, and central blood volume mobilization. In heart failure, ventricular function is compromised, and MMA elicits peripheral vasoconstriction. Ventricular-vascular coupling reflects the efficiency of energy transfer from the left ventricle to the systemic circulation and is calculated as the ratio of effective arterial elastance ( Ea) to left ventricular maximal elastance ( Emax). The effect of MMA on Ea in normal subjects is unknown. Furthermore, whether muscle metaboreflex control of Ea is altered in heart failure has not been investigated. We utilized two previously published methods of evaluating Ea [end-systolic pressure/stroke volume ( EaPV)] and [heart rate × vascular resistance ( EaZ)] during rest, mild treadmill exercise, and MMA (induced via partial reductions in hindlimb blood flow imposed during exercise) in chronically instrumented conscious canines before and after induction of heart failure via rapid ventricular pacing. In healthy animals, MMA elicits significant increases in effective arterial elastance and stroke work that likely maintains ventricular-vascular coupling. In heart failure, Ea is high, and MMA-induced increases are exaggerated, which further exacerbates the already uncoupled ventricular-vascular relationship, which likely contributes to the impaired ability to raise stroke work and cardiac output during exercise in heart failure.

Spontaneous baroreflex control of heart rate versus cardiac output: altered coupling in heart failure

2008 ◽  
Vol 294 (3) ◽  
pp. H1304-H1309 ◽  
Author(s):  
Javier A. Sala-Mercado ◽  
Masashi Ichinose ◽  
Robert L. Hammond ◽  
Matthew Coutsos ◽  
Tomoko Ichinose ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Baroreflex Control ◽  
Ventricular Systolic Pressure ◽  
Linear Relationships ◽  
Before And After ◽  
Spontaneous Baroreflex

Dynamic cardiac baroreflex responses are frequently investigated by analyzing the spontaneous reciprocal changes in arterial pressure and heart rate (HR). However, whether the spontaneous baroreflex-induced changes in HR translate into changes in cardiac output (CO) is unknown. In addition, this linkage between changes in HR and changes in CO may be different in subjects with heart failure (HF). We examined these questions using conscious dogs before and after pacing-induced HF. Spontaneous baroreflex sensitivity in the control of HR and CO was evaluated as the slopes of the linear relationships between HR or CO and left ventricular systolic pressure (LVSP) during spontaneous sequences of greater or equal to three consecutive beats when HR or CO changed inversely versus pressure. Furthermore, the translation of baroreflex HR responses into CO responses (HR-CO translation) was examined by computing the overlap between HR and CO sequences. In normal resting conditions, 44.0 ± 4.4% of HR sequences overlapped with CO sequences, suggesting that only around half of the baroreflex HR responses cause CO responses. In HF, HR-LVSP, CO-LVSP, and the HR-CO translation significantly decreased compared with the normal condition (−2.29 ± 0.5 vs. −5.78 ± 0.7 beats·min−1·mmHg−1; −70.95 ± 11.8 vs. −229.89 ± 29.6 ml·min−1·mmHg−1; and 19.66 ± 4.9 vs. 44.0 ± 4.4%, respectively). We conclude that spontaneous baroreflex HR responses do not always cause changes in CO. In addition, HF significantly decreases HR-LVSP, CO-LVSP, and HR-CO translation.

Muscle metaboreflex activation attenuates spontaneous baroreflex control of heart rate during dynamic exercise

2007 ◽  
Vol 21 (5) ◽  
Author(s):  
Masashi Ichinose ◽  
Javier A Sala‐Mercado ◽  
Tomoko Ichinose ◽  
Marco Pallante ◽  
Ferdinando Iellamo ◽  
...  
Keyword(s):  
Heart Rate ◽  
Dynamic Exercise ◽  
Baroreflex Control ◽  
Muscle Metaboreflex ◽  
Spontaneous Baroreflex

scholarly journals Progressive Muscle Metaboreflex Activation Gradually Decreases Spontaneous Heart Rate Baroreflex Sensitivity During Dynamic Exercise

2008 ◽  
Vol 22 (S1) ◽  
Author(s):  
Javier A. Sala‐Mercado ◽  
Masashi Ichinose ◽  
Matthew Coutsos ◽  
Tomoko Ichinose ◽  
Donal S. O'Leary
Keyword(s):  
Heart Rate ◽  
Baroreflex Sensitivity ◽  
Dynamic Exercise ◽  
Muscle Metaboreflex

Baroreflex stabilization of the double product

1999 ◽  
Vol 277 (5) ◽  
pp. H1679-H1689 ◽  
Author(s):  
Bruce N. van Vliet ◽  
Jean-Pierre Montani
Keyword(s):  
Heart Rate ◽  
Regression Analysis ◽  
Baroreflex Sensitivity ◽  
Left Ventricular ◽  
Rate Of Change ◽  
Double Product ◽  
Baroreflex Control ◽  
Indirect Indicator ◽  
The Mean ◽  
The Ideal

We investigated whether the baroreflex control of heart rate (HR) stabilizes the product of arterial pressure (PA) and HR, called the double product (DP), an indirect indicator of left ventricular oxygen consumption. During pharmacological increases and decreases of PA in conscious rabbits, the mean (±SE) rate of change of the DP with respect to PA(dDP/dPA) was −88 ± 36 and −20 ± 36 DP units/mmHg, respectively. Regression analysis of all peak responses obtained in individual rats produced a dDP/dPA value of 15 ± 16 DP units/mmHg. These estimates were significantly less than the dDP/dPA value predicted if HR were constant (184 ± 7 DP units/mmHg) and were not significantly different from zero. We also compared values of baroreflex sensitivity (BRS) from the literature with those calculated to provide ideal stabilization of the DP. BRS values were significantly correlated with the calculated ideal values ( R = 0.95; n = 14). BRS averaged 128 ± 24% of the ideal value in all species and 148 ± 28% in mammals and birds. Our results suggest that stabilization of the DP is a common consequence of the baroreflex control of heart rate.

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