Baroreceptor reflex sensitivity index derived from Phase 4 of te Valsalva maneuver.

Palmero, H A; Caeiro, T; Iosa, Daniel; Bas, Josep M.

doi:10.1161/01.hyp.3.6_pt_2.ii-134

Cited by 78 publications

(69 citation statements)

References 16 publications

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“…In contrast to the observations of Palmero et al (1981), we have found no evidence for abolition of the CSBHRR during the VM. We have shown that the intensity ofexercise-induced breathlessness in normal subjects is related to the level of prevailing ventilation and is independent of coexisting hypercapnia or hypoxia (Lane et al 1990).…”

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confidence: 99%

“…In addition, activity in the premotor cortex and SMA suggests that non-primary motor areas are involved in the voluntary control of breathing, as they are in limb movement (Colebatch et al 1990). (Palmero et al 1981; Ogura et al 1985).This was investigated using the neck suction technique to stimulate the carotid sinus baroreceptor heart-rate reflex (CSBHRR) during inspiratory apnoea, and at three points during the VAI. The carotid sinus baroreceptors of 16 healthy volunteers (aged 18-26 years) were stimulated using 4s periods of neck suction (NS) at -50 mmHg, during apnoea at the end of a normal inspiration.…”

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confidence: 99%

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Proceedings of the Physiological Society, 10‐11 January 1991, Charing Cross and Westminster Meeting: Communications

1991

The Journal of Physiology

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We have provoked sustained mechanical alternans (MA), by a combination of low temperature (27 ± 0. PC) and rapid pacing (3-4.5 Hz) in isometric guinea-pig papillary muscles (0.32-0.89 mm maximum diameter, n = 8) superfused with Tris (20 mM) buffered Tyrode (pH 7.3-7.4) aerated with 100% 02.Mechanical restitution curves were plotted using data obtained by introducing test stimuli at various intervals following trains of steady-state stimuli. Figure 1 shows the curves for test stimuli applied after the small and large contractions during sustained MA for one preparation. The mean half-times for restitution following the small and large contractions in MA are 140 ± 40 ms (mean ± S.E.M., n = 7) and 150 ± 41 ms (mean ± S.E.M., n = 8) respectively. The difference between the means is not statistically significant. These results do not support the hypothesis (Mahler & Rogel, 1970) that MA results from dependence of the restitution time course upon the myocardial force of a given contraction. REFERENCE Mahler, H. & Rogel, S. (1970). Clin. Sci. 39, 625-639. J. Physiol. (1991) Force in relation to membrane potential was studied in voltage-clamped ferret papillary muscles at 37TC using the single sucrose gap technique. This method allows accurate force measurements during voltage clamp. The preparation was stimulated with rectangular voltage clamp pulses at a rate of 1.0 Hz. The holding membrane potantial was -40mV and the preparation was depolarized to + 20 mV for 200 ms to initiate force production (clamps 'O'in Fig. 1). A test clamp denoted '1' was introduced at selected times. It consisted of an initial depolarizing step of 20 ms duration to +20 mV in order to initiate the first part of the second inward current (Ica,f, Arlock & Noble, 1985). This was followed by a second voltage step to different potentials between -20 and +20 mV at a varied duration (0.2-3.0 s). Test clamp 1 was followed by a second and a third test clamp pulse (2, 3 in Fig. 1) with the same amplitude and duration as in the control period. The variations in test clamp 1 produced different degrees of contractile potentiation of test contractions 2 and 3. There was a straight relation between peak force of contraction 3 (F3) and peak force of contraction 2 (F2) (Fig. 1). When the holding potential between clamps 2 and 3 was -70 mV, the curve shifted downwards in a more or less parallel manner compared to the curve obtained at -4OmV (Fig. 1). The straight relation between F3 and F2 could be explained by a recirculation of calcium within the cardiac cell. The shift of the curve would follow from an increased outflow of calcium via sodium-calcium exchange caused by a greater driving force. The unchanged slope suggests that recirculation mainly takes place during depolarisation. 3PT ,B-Adrenergic agonists can restore action potentials of ventricular myocytes rendered inexcitable by hyperkalaemia (Paterson et al. 1990). Hence we have argued that catecholamines may provide protection from the high (7-8 mM) plasma K+ levels found in exercise-induced h...

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confidence: 99%

Proceedings of the Physiological Society, 10‐11 January 1991, Charing Cross and Westminster Meeting: Communications

1991

The Journal of Physiology

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“…They discussed the difference of the two methods; drug-induced baroreflex quantifies the phasic reflex cardiac baroreflex activity, while that of spontaneous-BRS indicates the tonic cardiac parasympathetic activity. The Valsalva-BRS has been shown to be similar to the BRS evaluated by the phenylephrine method (12,29), which engages parasympathetic nerve response with very large excursions of BP. There are common characteristics between morning hypertension and the phenylephrine injection test: a transient elevation of BP levels and activation of α-adrenergic receptors (30,31).…”

Section: Arterial Brs and Bp Controlmentioning

confidence: 80%

“…After a few practice rounds, three 10-s Valsalva maneuvers were per- formed, separated by 3-min recovery periods. We used the slope method to assess cardiovagal BRS during phase IV arterial pressure elevations (12). We used linear regression analysis to calculate the magnitude of the increases in R-R intervals as a function of the elevation of the SBP for the calculation of BRS evaluated by the Valsalva method (Valsalva-BRS).…”

Section: Baroreflex Sensitivitymentioning

confidence: 99%

Factors Associated with Baroreflex Sensitivity: Association with Morning Blood Pressure

et al. 2007

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Baroreflex sensitivity (BRS) is a primary mechanism for acute and chronic control of blood pressure (BP).However, there are few data showing the relationship between BRS and ambulatory BP (ABP). We assessed the hypothesis that BRS specifically contributes to some specific parameters of ABP in never-treated hypertensive/normotensive subjects. We studied 128 subjects (mean age: 54.5 ± 13 years, 60% male) consisting of 92 untreated hypertensive and 36 normotensive subjects. Radial tonometric BP and simultaneous RR interval were recorded for 10 min, and the Valsalva maneuver was performed 3 times for each subject. BRS was calculated in two ways: the spontaneous-BRS by the spectral method, and the Valsalva-BRS by the slope method, using commercial software. ABP monitoring was performed on the same day as the BRS test.

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“…A noninvasive method based on BP changes during the late phases of Valsalva manoeuvre was proposed. Indeed, phase IV of the Valsalva manoeuvre is normally characterized by BP overshoot with concomitant reflex bradycardia, allowing to calculate cardiac vagal baroreflex gain [32][33][34][35].…”

Section: Calculation Of the Baroreflex Gainmentioning

confidence: 99%

Squatting test: a dynamic postural manoeuvre to study baroreflex sensitivity

Scheen

Philips

2011

Clin Auton Res

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Baroreceptor reflex sensitivity index derived from Phase 4 of te Valsalva maneuver.

Cited by 78 publications

References 16 publications

Proceedings of the Physiological Society, 10‐11 January 1991, Charing Cross and Westminster Meeting: Communications

Proceedings of the Physiological Society, 10‐11 January 1991, Charing Cross and Westminster Meeting: Communications

Factors Associated with Baroreflex Sensitivity: Association with Morning Blood Pressure

Squatting test: a dynamic postural manoeuvre to study baroreflex sensitivity

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