Phase synchronization of baroreflex oscillations of blood pressure and pulse interval in rats: the effects of cardiac autonomic blockade and gradual blood loss

2019 ◽  
Vol 40 (5) ◽  
pp. 054003 ◽  
Author(s):  
Vladimir O Negulyaev ◽  
Olga S Tarasova ◽  
Nadezhda V Tarasova ◽  
Elena V Lukoshkova ◽  
Olga L Vinogradova ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Loss ◽  
Phase Synchronization ◽  
Pulse Interval ◽  
Autonomic Blockade

scholarly journals Improved Cardiovascular Tolerance to Hemorrhage after Oral Resveratrol Pretreatment in Dogs

2021 ◽  
Vol 8 (7) ◽  
pp. 129
Author(s):  
Jennifer Davis ◽  
Anthea L. Raisis ◽  
Claire R. Sharp ◽  
Rachel E. Cianciolo ◽  
Steven C. Wallis ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Placebo Group ◽  
Blood Loss ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Kidney Injury ◽  
Bleeding Risk ◽  
Canine Model ◽  
Coagulation Parameters ◽  
Renal Tubular

Resveratrol has been shown to preserve organ function and improve survival in hemorrhagic shock rat models. This study investigated whether seven days of oral resveratrol could improve hemodynamic response to hemorrhage and confer benefits on risk of acute kidney injury (AKI) without inducing coagulopathy in a canine model. Twelve greyhound dogs were randomly allocated to receive oral resveratrol (1000 mg/day) or placebo for seven days prior to inducing hemorrhage until a targeted mean blood pressure of ≤40 mmHg was achieved. AKI biomarkers and coagulation parameters were measured before, immediately following, and two hours after hemorrhage. Dogs were euthanized, and renal tissues were examined at the end of the experiment. All investigators were blinded to the treatment allocation. A linear mixed model was used to assess effect of resveratrol on AKI biomarkers and coagulation parameters while adjusting for volume of blood loss. A significant larger volume of blood loss was required to achieve the hypotension target in the resveratrol group compared to placebo group (median 64 vs. 55 mL/kg respectively, p = 0.041). Although histological evidence of AKI was evident in all dogs, the renal tubular injury scores were not significantly different between the two groups, neither were the AKI biomarkers. Baseline (pre-hemorrhage) maximum clot firmness on the Rotational Thromboelastometry (ROTEM®) was stronger in the resveratrol group than the placebo group (median 54 vs. 43 mm respectively, p = 0.009). In summary, seven days of oral resveratrol did not appear to induce increased bleeding risk and could improve greyhound dogs’ blood pressure tolerance to severe hemorrhage. Renal protective effect of resveratrol was, however, not observed.

Systemic and regional hemodynamics after nitric oxide synthase inhibition: role of a neurogenic mechanism

1994 ◽  
Vol 267 (1) ◽  
pp. R84-R88 ◽  
Author(s):  
M. Huang ◽  
M. L. Leblanc ◽  
R. L. Hester
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Cardiac Output ◽  
No Synthase ◽  
Before And After ◽  
Regional Hemodynamics ◽  
Autonomic Blockade ◽  
Infusion Of Norepinephrine ◽  
Oxide Synthase

The study tested the hypothesis that the increase in blood pressure and decrease in cardiac output after nitric oxide (NO) synthase inhibition with N omega-nitro-L-arginine methyl ester (L-NAME) was partially mediated by a neurogenic mechanism. Rats were anesthetized with Inactin (thiobutabarbital), and a control blood pressure was measured for 30 min. Cardiac output and tissue flows were measured with radioactive microspheres. All measurements of pressure and flows were made before and after NO synthase inhibition (20 mg/kg L-NAME) in a group of control animals and in a second group of animals in which the autonomic nervous system was blocked by 20 mg/kg hexamethonium. In this group of animals, an intravenous infusion of norepinephrine (20-140 ng/min) was used to maintain normal blood pressure. L-NAME treatment resulted in a significant increase in mean arterial pressure in both groups. L-NAME treatment decreased cardiac output approximately 50% in both the intact and autonomic blocked animals (P < 0.05). Autonomic blockade alone had no effect on tissue flows. L-NAME treatment caused a significant decrease in renal, hepatic artery, stomach, intestinal, and testicular blood flow in both groups. These results demonstrate that the increase in blood pressure and decreases in cardiac output and tissue flows after L-NAME treatment are not dependent on a neurogenic mechanism.

Evaluation of baroreceptor reflex by blood pressure monitoring in unanesthetized cats

1988 ◽  
Vol 254 (2) ◽  
pp. H377-H383 ◽  
Author(s):  
G. Bertinieri ◽  
M. Di Rienzo ◽  
A. Cavallazzi ◽  
A. U. Ferrari ◽  
A. Pedotti ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Regression Coefficient ◽  
Blood Pressure Monitoring ◽  
Sinus Node ◽  
Pulse Interval ◽  
Pressure Monitoring ◽  
Physiological Conditions ◽  
Average Variation

The arterial baroreceptor control of the sinus node operating in unanesthetized conditions was evaluated in 10 cats in which blood pressure was recorded intra-arterially and scanned by a computer to identify the "spontaneous" sequences of three or more consecutive beats in which systolic blood pressure (SBP) progressively rose and pulse interval (PI) progressively lengthened (type 1 sequences) or SBP progressively fell and PI progressively shortened (type 2 sequences). Many type 1 and 2 three-beat sequences were found; four-, five-, and six-beat sequences of either type were progressively less common, and sequences longer than six beats were almost never identified. The regression coefficient was 30% greater for type 1 than for type 2 sequences. However a prominent feature of either regression coefficient was a wide scattering in each cat (average variation coefficient 50.9 +/- 5.5%). The regression coefficient values were related to some extent to the PI but not to the SBP existing at the beginning of the sequence. Sinoaortic denervation dramatically reduced the number of sequences of either type. These data validate a method for collecting a large number of observations on the baroreceptor-heart rate reflex in physiological conditions. This method may improve understanding of baroreflex involvement in integrated cardiovascular regulation.

Modulation of carotid baroreflex responsiveness in man: effects of posture and propranolol

1976 ◽  
Vol 41 (3) ◽  
pp. 383-387 ◽  
Author(s):  
D. L. Eckberg ◽  
F. M. Abboud ◽  
A. L. Mark
Keyword(s):  
Angina Pectoris ◽  
Supine Position ◽  
Baroreflex Sensitivity ◽  
Pulse Interval ◽  
Upright Posture ◽  
Adrenergic Stimulation ◽  
Interval Prolongation ◽  
Carotid Baroreflex ◽  
Before And After ◽  
Autonomic Blockade

Carotid baroreceptors were stimulated with graded neck suction in supine and standing volunteers, before and after autonomic blockade, to determine the influence of posture on baroreflex responsiveness. Propranolol significantly augmented baroreflex pulse interval prolongation in the supine position. Upright posture did not modify baroreflex pulse interval responses prior to propranolol, but significantly augmented responses after propranolol. The results suggest that standing enhances baroreflex sensitivity, but that under normal circumstances, this effect is masked by beta-adrenergic stimulation. Augmentation of baroreflex pulse interval prolongation in the supine and standing positions by propranolol may contribute to the effectiveness of this drug in angina pectoris and labile hypertension.

Three new antihypertensive drugs: esbatal, envacar and vatensol

1964 ◽  
Vol 2 (11) ◽  
pp. 41-42
Keyword(s):  
Blood Pressure ◽  
Blood Loss ◽  
Thiazide Diuretic ◽  
Antihypertensive Drugs ◽  
Standing Position ◽  
Adrenergic Blockade ◽  
Concurrent Administration ◽  
Hot Environment ◽  
Nasal Stuffiness

These chemically related drugs lower the blood pressure by blocking adrenergic neurones, and their effects resemble those of guanethidine and bretylium. Concurrent administration of a thiazide diuretic potentiates each of these drugs, thus allowing the dose to be reduced. As might be expected the greatest reduction in blood pressure normally occurs in the standing position, but symptoms of hypotension, such as faintness, giddiness and weakness occur if the dose is excessive or under conditions which potentiate the effect of adrenergic blockade, for example, on first rising from bed, in a hot environment, during and after exercise, and after blood loss. Other symptoms caused by adrenergic blockade, such as nasal stuffiness and failure of ejaculation are common. Impotence has been reported.

scholarly journals Disruption of phase synchronization between blood pressure and muscle sympathetic nerve activity in postural vasovagal syncope

2013 ◽  
Vol 305 (8) ◽  
pp. H1238-H1245 ◽  
Author(s):  
Christopher E. Schwartz ◽  
Elisabeth Lambert ◽  
Marvin S. Medow ◽  
Julian M. Stewart
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Phase Synchronization ◽  
Vasovagal Syncope ◽  
Muscle Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Control Subjects ◽  
Late Stages

Withdrawal of muscle sympathetic nerve activity (MSNA) may not be necessary for the precipitous fall of peripheral arterial resistance and arterial pressure (AP) during vasovagal syncope (VVS). We tested the hypothesis that the MSNA-AP baroreflex entrainment is disrupted before VVS regardless of MSNA withdrawal using the phase synchronization between blood pressure and MSNA during head-up tilt (HUT) to measure reflex coupling. We studied eight VVS subjects and eight healthy control subjects. Heart rate, AP, and MSNA were measured during supine baseline and at early, mid, late, and syncope stages of HUT. Phase synchronization indexes, measuring time-dependent differences between MSNA and AP phases, were computed. Directionality indexes, indicating the influence of AP on MSNA (neural arc) and MSNA on AP (peripheral arc), were computed. Heart rate was greater in VVS compared with control subjects during early, mid, and late stages of HUT and significantly declined at syncope ( P = 0.04). AP significantly decreased during mid, late, and syncope stages of tilt in VVS subjects only ( P = 0.001). MSNA was not significantly different between groups during HUT ( P = 0.700). However, the phase synchronization index significantly decreased during mid and late stages in VVS subjects but not in control subjects ( P < .001). In addition, the neural arc was significantly affected more than the peripheral arc before syncope. In conclusion, VVS is accompanied by a loss of the synchronous AP-MSNA relationship with or without a loss in MSNA at faint. This provides insight into the mechanisms behind the loss of vasoconstriction and drop in AP independent of MSNA at the time of vasovagal faint.

Biofeedback of R-wave to Pulse Interval Produces Differential Learning of Blood Pressure Control

1996 ◽  
Vol 25 (1) ◽  
pp. 17-25
Author(s):  
Harald Rau ◽  
Rolf Weitkunat ◽  
Stuart Brody ◽  
Michael Bührer ◽  
Monika Jonak ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Pressure Control ◽  
Pressure Control ◽  
Pulse Interval ◽  
Differential Learning

scholarly journals Sequential spectral analysis of 24-hour blood pressure and pulse interval in humans.

Hypertension ◽  
1990 ◽  
Vol 16 (4) ◽  
pp. 414-421 ◽  
Author(s):  
G Parati ◽  
P Castiglioni ◽  
M Di Rienzo ◽  
S Omboni ◽  
A Pedotti ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Spectral Analysis ◽  
Pulse Interval

scholarly journals CHANGE OF FUNCTIONAL AND LABORATORY PARAMETERS AFTER COMPENSATION OF ACUTE BLOOD LOSS WITH COOLED HYPERTONIC SOLUTION IN EXPERIMENT

2018 ◽  
pp. 83-94
Author(s):  
A. V. Krupin ◽  
I. A. Shperling ◽  
P. A. Romanov ◽  
M. I. Shperling
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Loss ◽  
Blood Plasma ◽  
Hypertonic Solution ◽  
Acute Blood Loss ◽  
External Temperature ◽  
Heat Chamber ◽  
Quantitative Indicators ◽  
Experimental Group

Relevance.High efficiency of hypertonic (hyperosmolar) solutions in acute blood loss is known. However, data on changes in the body, developing as a result of infusion of such drugs (including cooled) in the providing of care after acute blood loss is limited or absent. This fact complicates the development of tactics in their use, especially in emergency situations at low temperatures.Intention.To reveal features of functional and laboratory indicators In experiments on animals as a result of infusion of warm (+22 °С) or the cooled (–3 °С) hypertonic solution based on hydroxyethyl starch and sodium chloride (HyperHAES, further – HHES) at the acute blood loss of 50 % of blood volume (BV).Methodology.Animals (20 male sheep) with modeled blood loss were distributed into 2 experimental and 2 control groups of 5 animals each. Sheep in the 1st experimental group were placed in the heat chamber with temperature –7 °С for 15 min. Then they underwent the intravenous infusion of a cooled HHES at a dose of 4 ml/kg of weight through the jugular vein with a disposable syringe (volume 20 ml) evenly with a speed of 60 ml per minute. After that they were left in the heat chamber until the time of 1 hour in total. Individuals in the 2nd experimental group were injected with an equivalent volume of warm solution during the corresponding periods of the experiment at an external temperature of +22 °C. 1 hour after beginning of the infusion all animals were intravenously injected with colloidal solution based on hydroxyethyl starch (“Voluven”) at an external temperature of +22 °C. During 1 day the dynamics of rectal temperature, arterial pressure, heart rate and respiratory movements, osmolarity of blood plasma and content of osmotically active components, quantitative indicators of red blood were evaluated.Results.Animals at a temperature of +22 °C or at a temperature of –7 °C died in (82 ± 3) min and (70 ± 5) min (p < 0.05) respectively after the start of exfusion. Intravenous fluids (warm or cooled HHES) ensured the survival in 100 % of cases. As a result of blood loss, subsequent infusion of cooled HHES and following presence in the heat chamber, rectal temperature in sheep decreased by 4.9 °C (14.2%, p < 0.05) relative to the initial values. Two and 4 min after infusion of cooled or warm HHES systolic blood pressure increased by 24.9 % (p < 0.05) and 14.9 % (p < 0.05), respectively, and were restored to the normal level during the following 40 min. Infusion of “Voluven” contributed to the stabilization of blood pressure within 1 day after infusion of HHES. Blood loss led to increased heart rate by 2.1 times (p < 0.05), infusion of HHES slightly reduced the severity of tachycardia. Within 10 minutes after the introduction of cooled HHES, dynamics of heart rate was less stable. Infusion of warm or cooled HHES increased osmolarity of blood plasma by 9.5–9.9 % (p < 0.05), which was associated with an increase of sodium and glucose concentrations in blood. Infusion of “Voluven” reduced osmolarity of blood plasma, which became similar to initial values at the end of Day 1 after infusion of HHES. Blood loss, infusion of HHES and “Voluven” decreased quantitative indicators of red blood via removal of red blood cells from the bloodstream, as well as compensatory and post-transfusion hemodilution.Conclusion.The infusion of warm or cold hypertonic saline (HyperHAES) ensures the survival of experimental animals in post-hemorrhagic period. The positive effect of the drug is associated with compensatory haemodilution (including increased osmolarity of blood plasma), as well as with better functioning of the cardiovascular system. Specific cooled HHES effects include an earlier and pronounced rise in blood pressure. Considering changes in functional and laboratory parameters after infusion of warm or cooled HHES, a reliable system should be developed to remove casualties from emergency areas and to take earlier and complete diagnostic and treatment measures.

scholarly journals Dependency Structures in Differentially Coded Cardiovascular Time Series

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Tatjana Tasic ◽  
Sladjana Jovanovic ◽  
Omer Mohamoud ◽  
Tamara Skoric ◽  
Nina Japundzic-Zigon ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Time Series ◽  
Systolic Blood Pressure ◽  
Dynamic Range ◽  
Time Lag ◽  
Conditional Entropy ◽  
Pulse Interval ◽  
Time Lags ◽  
Aging Rats ◽  
Male Wistar Rats

Objectives. This paper analyses temporal dependency in the time series recorded from aging rats, the healthy ones and those with early developed hypertension. The aim is to explore effects of age and hypertension on mutual sample relationship along the time axis.Methods. A copula method is applied to raw and to differentially coded signals. The latter ones were additionally binary encoded for a joint conditional entropy application. The signals were recorded from freely moving male Wistar rats and from spontaneous hypertensive rats, aged 3 months and 12 months.Results. The highest level of comonotonic behavior of pulse interval with respect to systolic blood pressure is observed at time lagsτ=0, 3, and 4, while a strong counter-monotonic behavior occurs at time lagsτ=1and 2.Conclusion. Dynamic range of aging rats is considerably reduced in hypertensive groups. Conditional entropy of systolic blood pressure signal, compared to unconditional, shows an increased level of discrepancy, except for a time lag 1, where the equality is preserved in spite of the memory of differential coder. The antiparallel streams play an important role at single beat time lag.

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