Lack of association between systolic blood pressure and blood viscosity in normotensive healthy subjects

2012 ◽  
Vol 51 (1) ◽  
pp. 35-41 ◽  
Author(s):  
Concetta Irace ◽  
Claudio Carallo ◽  
Faustina Scavelli ◽  
Antonio Loprete ◽  
Valentina Merante ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Blood Viscosity ◽  
Healthy Subjects

Feedback effects of circulating norepinephrine on sympathetic outflow in healthy subjects

2005 ◽  
Vol 288 (2) ◽  
pp. H710-H715 ◽  
Author(s):  
Mikko P. Tulppo ◽  
Heikki V. Huikuri ◽  
Elli Tutungi ◽  
Derek S. Kimmerly ◽  
Adrian W. Gelb ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Sympathetic Activity ◽  
Healthy Subjects ◽  
Blood Pressure Variability ◽  
Feedback Inhibition ◽  
Adrenergic Blockade ◽  
Sympathetic Outflow ◽  
Systolic Blood Pressure Variability ◽  
Normalized Units

The amplitude of low-frequency (LF) oscillations of heart rate (HR) usually reflects the magnitude of sympathetic activity, but during some conditions, e.g., physical exercise, high sympathetic activity results in a paradoxical decrease of LF oscillations of HR. We tested the hypothesis that this phenomenon may result from a feedback inhibition of sympathetic outflow caused by circulating norepinephrine (NE). A physiological dose of NE (100 ng·kg−1·min−1) was infused into eight healthy subjects, and infusion was continued after α-adrenergic blockade [with phentolamine (Phe)]. Muscle sympathetic nervous activity (MSNA) from the peroneal nerve, LF (0.04–0.15 Hz) and high frequency (HF; 0.15–0.40 Hz) spectral components of HR variability, and systolic blood pressure variability were analyzed at baseline, during NE infusion, and during NE infusion after Phe administration. The NE infusion increased the mean blood pressure and decreased the average HR ( P < 0.01 for both). MSNA (10 ± 2 vs. 2 ± 1 bursts/min, P < 0.01), LF oscillations of HR (43 ± 13 vs. 35 ± 13 normalized units, P < 0.05), and systolic blood pressure (3.1 ± 2.3 vs. 2.0 ± 1.1 mmHg2, P < 0.05) decreased significantly during the NE infusion. During the NE infusion after PHE, average HR and mean blood pressure returned to baseline levels. However, MSNA (4 ± 2 bursts/min), LF power of HR (33 ± 9 normalized units), and systolic blood pressure variability (1.7 ± 1.1 mmHg2) remained significantly ( P < 0.05 for all) below baseline values. Baroreflex gain did not change significantly during the interventions. Elevated levels of circulating NE cause a feedback inhibition on sympathetic outflow in healthy subjects. These inhibitory effects do not seem to be mediated by pressor effects on the baroreflex loop but perhaps by a presynaptic autoregulatory feedback mechanism or some other mechanism that is not prevented by a nonselective α-adrenergic blockade.

scholarly journals Relation of body mass index (BMI) with cardiovascular response to head up tilt in healthy subjects

2020 ◽  
Vol 15 (1) ◽  
pp. 6-10
Author(s):  
Sadia Afrin Rimi ◽  
Shamima Sultana ◽  
Iffat Rezwana ◽  
Sultana Ferdousi
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Systolic Blood Pressure ◽  
Healthy Subjects ◽  
Cardiovascular Response ◽  
Tilt Test ◽  
Tilt Table ◽  
Chi Square ◽  
Female Head ◽  
Head Up Tilt

Background: Tilt table test is used for the last few decades to detect cause in unexplained syncope. The response to tilting may vary physiologically with obesity. Objective: To assess the relationship of BMI to cardiovascular response to tilting. Methods: This experimental study was conducted from March 2019 to Feb 2020 on 90 healthy subjects with different BMI. Fifty one subjects of both gender with BMI 18.5-24.9 kg/m2 were included in the non-obese group and 39 subjects of both gender with BMI of 25-29.9 kg/m2 were included in overweight group and they were further subdivided into male and female. Head up tilting was done for 10 minutes at 600 by using a motorized tilt table. Systolic blood pressure (SBP), diastolic blood pressure (DBP) were recorded by an automatic sphygmomanometer. Heart rate (HR) and peripheral capillary oxygen saturation (SpO2) were measured by a pulse oximeter. For statistical analysis, Independent sample ‘t’ test, Pearson’s correlation test and Chi square tests were applied. Results: Significantly smaller rise of heart rate was observed in overweight males and greater fall of systolic blood pressure was observed in overweight females. Conclusion: This study concluded that over weight is associated with reduced orthostatic tolerance to head up tilt test in both genders. J Bangladesh Soc Physiol. 2020, June; 15(1): 6-10

Effects of catecholamines and potassium on cardiovascular performance in the rabbit

1992 ◽  
Vol 73 (4) ◽  
pp. 1413-1418 ◽  
Author(s):  
D. J. Paterson ◽  
G. J. Blake ◽  
S. P. Leitch ◽  
S. M. Phillips ◽  
H. F. Brown
Keyword(s):  
Blood Pressure ◽  
Cardiac Arrest ◽  
Systolic Blood Pressure ◽  
Healthy Subjects ◽  
Plasma Potassium ◽  
Aortic Flow ◽  
Maximum Output ◽  
Output Pressure ◽  
Cardiovascular Performance ◽  
Exercise Induced

Resting subjects risk cardiac arrest if plasma potassium ([K+]p) is raised rapidly to 7–9 mM, but brief bouts of exhaustive exercise in healthy subjects can give similar [K+]p without causing cardiac problems. We investigated the effects of [K+]p and catecholamines on systolic blood pressure (SBP) and mean aortic flow (MAF) in anesthetized rabbits and on maximum output pressure (MOP) in isolated working rabbit hearts. In six rabbits, hyperkalemia (11.4 +/- 0.4 mM) caused a fall in SBP from 116 +/- 6 to 49 +/- 6 mmHg and in MAF from 373 +/- 30 to 181 +/- 53 ml/min (P < 0.01). Raising [K+]p (11.6 +/- 0.3 mM) with norepinephrine (NE) (1.3 micrograms.kg-1.min-1 iv), however, increased SBP from 108 +/- 7 to 150 +/- 6 mmHg (P < 0.01) and MAF from 347 +/- 42 to 434 +/- 35 ml/min (P < 0.01). In 19 isolated working hearts, perfusion with 8 mM K+ Tyrode and then 12 mM K+ Tyrode reduced MOP from 87 +/- 3 (control 4 mM K+) to 67 +/- 3 (8 mM K+) and 51 +/- 2 cmH2O (12 mM K+) (P < 0.01); 12 mM K+ Tyrode with 0.08 microM NE or epinephrine, however, increased MOP from 67 +/- 6 (in 8 mM K+) to 85 +/- 6 cmH2O (NE) and from 58 +/- 2 to 76 +/- 5 cmH2O (epinephrine) (P < 0.01). Catecholamines may therefore play a key role in protecting the heart from exercise-induced hyperkalemia.

scholarly journals Nonlinearities and asymmetries of the human cardiovagal baroreflex

2005 ◽  
Vol 288 (5) ◽  
pp. R1339-R1346 ◽  
Author(s):  
Brian E. Hunt ◽  
William B. Farquhar
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Predictive Value ◽  
Healthy Subjects ◽  
Model Parameters ◽  
Set Point ◽  
Response Range ◽  
Reflex Gain ◽  
Insight Into ◽  
Nonlinear Nature

To determine whether an approach such as the modified Oxford technique can consistently produce data that reveal the nonlinear nature of the cardiovagal baroreflex and to ascertain whether the model parameters provide unique insight into baroreflex function, we retrospectively examined 91 baroreflex trials (38 subjects, 27 men and 11 women, ages 22–72 yr). The modified Oxford technique (bolus sodium nitroprusside followed by bolus phenylephrine) was used to perturb blood pressure, and the resulting systolic blood pressure-R-R interval responses were plotted and modeled using a linear, a four-parameter symmetric, and a five-parameter asymmetric model. Several issues, such as the effect of data averaging, various approaches to gain estimation, and the predictive value of model parameters, were examined during reflex modeling. Sigmoid models accounted for a greater amount of the variance than did the linear model: linear r2 = 0.81 ± 0.01, four-parameter r2 = 0.90 ± 0.08, and five-parameter r2 = 0.90 ± 0.08 ( P < 0.05, linear vs. sigmoid models). Data averaging did not affect model fits. Although the four gain estimates (linear remodel, 1st derivative, peak, and set point) were statistically related, the set point gain was significantly lower than other estimates ( P < 0.05). Subgroup comparisons between young and older healthy subjects revealed differences in all indexes of cardiovagal baroreflex gain, as well as R-R interval operating range and curvature parameters. In conclusion, the modified Oxford technique consistently reveals the nonlinear nature of the human cardiovagal baroreflex. Moreover, of the parameters produced by the symmetric sigmoid model, only the response range provides unique information beyond that of reflex gain.

scholarly journals Cardiovascular response to strength training is more affected by intensity than volume in healthy subjects

2018 ◽  
Vol 11 (3) ◽  
Author(s):  
OC Moreira ◽  
CEP Oliveira ◽  
DG Matos ◽  
SF Silva ◽  
RC Hickner ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Resistance Exercise ◽  
Systolic Blood Pressure ◽  
Diastolic Blood Pressure ◽  
Healthy Subjects ◽  
Bench Press ◽  
Cardiovascular Response ◽  
Rate Pressure Product ◽  
Repetition Maximum

Objective: To determine and compare the cardiovascular responses to three resistance exercise protocols with different volumes and loads. Methods: The study included 15 healthy subjects, experienced in resistance training, who underwent supine bench press exercise with three different volumes and loads separated by 48 hours, with a crossover model: a) 4 repetitions at 90% of one repetition maximum (4/90%), b) 8 repetitions at 80% of one repetition maximum (8/80%), and c) 15 repetitions at 65% of one repetition maximum (15/65%). Immediately following each protocol, measures of heart rate, systolic and diastolic blood pressure were performed, and were used to calculate the rate pressure product. Results: The 4/90% protocol resulted in an increase in heart rate (Δ = 84.57%; effect size [ES] = 0.31), systolic blood pressure (Δ = 24.03%; ES = 0.42), diastolic blood pressure (Δ = 8.47%; ES = 0.27) and rate pressure product (Δ = 129.65%; ES = 0.54). The 8/80% protocol resulted in changes on: heart rate (Δ = 74.94%; ES = 0.57), systolic blood pressure (Δ = 20.67%; ES = 0.27), diastolic blood pressure (Δ = 6.91%; ES = 0.15) and rate pressure product (Δ = 111.78%; ES = 0.48). The 15/65% protocol resulted in alterations on: heart rate (Δ = 66.77%; ES = 0.39), systolic blood pressure (Δ = 16.85%; ES = 0.35), diastolic blood pressure (Δ = 3.38%; ES = 0.13) and rate pressure product (Δ = 96.41%; ES = 0.30). Increases in all variables pre to post resistance exercise were observed for all protocols (p < 0.05). When comparing the three different protocols, it was found that the heart rate (p < 0.001), systolic blood pressure (p = 0.034) and rate pressure product (p < 0.001), were more elevated in the 4/90% compared to the 15/65%. Conclusion: The bench press exercise performed with low volume and high intensity promotes a more pronounced cardiovascular response compared to the same exercise performed with high volume and low intensity.      

SYSTOLIC BLOOD PRESSURE AMPLIFICATION IS DECREASED DURING NIGHT HOURS IN HEALTHY SUBJECTS

2011 ◽  
Vol 29 ◽  
pp. e448-e449
Author(s):  
A. Bednarek ◽  
P. Jankowski ◽  
A. Olszanecka ◽  
A. Windak ◽  
D. Czarnecka ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Healthy Subjects ◽  
Pressure Amplification

scholarly journals Systolic blood pressure peak during maximal exercise testing: A possible determinant of endothelial turnover in healthy subjects

2009 ◽  
Vol 84 (7) ◽  
pp. 449-450
Author(s):  
Michele M. Ciulla ◽  
Carola Gianni ◽  
Pietro Broglia ◽  
Silvia Lonati ◽  
Ilaria Silvestris ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Exercise Testing ◽  
Healthy Subjects ◽  
Maximal Exercise ◽  
Pressure Peak

scholarly journals Development of Causal Interactions Between Systolic Blood Pressure and Inter-Beat Intervals in Adolescents

2015 ◽  
pp. 821-829 ◽  
Author(s):  
J. SVAČINOVÁ ◽  
M. JAVORKA ◽  
Z. NOVÁKOVÁ ◽  
E. ZÁVODNÁ ◽  
B. CZIPPELOVÁ ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Healthy Subjects ◽  
Baroreflex Sensitivity ◽  
Closed Loop ◽  
Loop Model ◽  
Bivariate Model ◽  
Causal Pathways ◽  
Linear Approach ◽  
Age Related

Systolic blood pressure (SBP) changes control the cardiac inter-beat intervals (IBI) duration via baroreflex. Conversely, SBP is influenced by IBI via non-baroreflex mechanisms. Both causal pathways (feedback – baroreflex and feedforward – non-baroreflex) form a closed loop of the SBP – IBI interaction. The aim of this study was to assess the age-related changes in the IBI – SBP interaction. We have non-invasively recorded resting beat-to-beat SBP and IBI in 335 healthy subjects of different age, ranging from 11 to 23 years. Using a linear autoregressive bivariate model we obtained gain (GainSBP,IBI, used traditionally as baroreflex sensitivity) and coherence (CohSBP,IBI) of the SBP–IBI interaction and causal gain and coherence in baroreflex (GainSBPIBI, CohSBPIBI) and coherence in non-baroreflex (CohIBISBP) directions separately. A non-linear approach was used for causal coupling indices evaluation (CSBPIBI, CIBISBP) quantifying the amount of information transferred between signals. We performed a correlation to age analysis of all measures. CohIBISBP and CIBISBP were higher than CohSBPIBI and CSBPIBI, respectively. GainSBP,IBI increased and CohSBPIBI decreased with age. The coupling indices did not correlate with age. We conclude that the feedforward influence dominated at rest. The increase of GainSBP,IBI with age was not found in the closed loop model. A decrease of CohSBPIBI could be related to a change in the cardiovascular control system complexity during maturation.

Sign in / Sign up

Export Citation Format

Share Document