Evidence for a specific influence of the nitrergic pathway on the peripheral pulse waveform in rabbits

The effects of a motorized passive simulated jogging device on descent of the arterial pulse waveform dicrotic notch: A single arm placebo-controlled cross-over trial

Whole Body Periodic Acceleration (WBPA, pGz), is a bed that moves the body headward to forward, adds pulses to the circulation inducing descent of the dicrotic notch (DN) on the pulse waveform with an increase in a/b ratio (a = the height of the pulse waveform and b = the height of the secondary wave). Since the WBPA is large, heavy, and non-portable, we engineered a portable device (Jogging Device, JD). JD simulates passive jogging and introduces pulsations to the circulation. We hypothesized that JD would increase the a/b ratio during and after its use. In Study A, a single-arm placebo-controlled cross-over trial was conducted in24 adults (53.8 ± 14.4 years) using JD or control (CONT) for 30 min. Blood pressure (BPs and BPd) and photoplethysmograph pulse (a/b) were measured at baseline (BL), during 30 min of JD or CONT, and 5 and 60 min after. In Study B (n = 20, 52.2 ± 7 years), a single-arm observational trial of 7 consecutive days of JD on BP and a/b, measured at BL, and after 7 days of JD and 48 and 72 hr after its discontinuation. In Study A, BPs, and BPd decreased during JD by 13% and 16%, respectively, while in CONT both increased by 2% and 2.5%, respectively. The a/b increased by 2-fold and remained greater than 2-fold at all-time points, with no change in a/b during CONT. In Study B, BPs and BPd decreased by 9% and remained below BL, at 72 hr after discontinuation of JD. DN descent also occurred after 7 days of JD with a/b increase of 80% and remained elevated by 60% for at least 72 h. JD improves acute and longer-term vascular hemodynamics with an increase in a/b, consistent with increased effects of nitric oxide (NO). JD may have significant clinical and public health implications.

Cardiovascular "Patterns" of H2S and SSNO--Mix Evaluated from 35 Rat Hemodynamic Parameters

This work is based on the hypothesis that it is possible to characterize the cardiovascular system just from the detailed shape of the arterial pulse waveform (APW). Since H₂S, NO donor S-nitrosoglutathione (GSNO) and their H₂S/GSNO products (SSNO⁻-mix) have numerous biological actions, we aimed to compare their effects on APW and to find characteristic “patterns” of their actions. The right jugular vein of anesthetized rats was cannulated for i.v. administration of the compounds. The left carotid artery was cannulated to detect APW. From APW, 35 hemodynamic parameters (HPs) were evaluated. H₂S transiently influenced all 35 HPs and from their cross-relationships to systolic blood pressure “patterns” and direct/indirect signaling pathways of the H₂S effect were proposed. The observed “patterns” were mostly different from the published ones for GSNO. Effect of SSNO⁻-mix (≤32 nmol kg⁻¹) on blood pressure in the presence or absence of a nitric oxide synthase inhibitor (L-NAME) was minor in comparison to GSNO, suggesting that the formation of SSNO⁻-mix in blood diminished the hemodynamic effect of NO. The observed time-dependent changes of 35 HPs, their cross-relationships and non-hysteresis/hysteresis profiles may serve as “patterns” for the conditions of a transient decrease/increase of blood pressure caused by H₂S.

Clinical and vascular responses to propranolol and candesartan in migraine patients: A randomized controlled clinical trial

Background:

Both propranolol and candesartan are prophylactic drugs for migraine, but with unknown mechanisms of action. The objectives of the present study were to investigate these drugs’ effects on arterial wall dynamics and the potential relation between their vascular and clinical effect.

Methods:

The study was based on data from a previously published randomized, placebo-controlled, triple-blinded, double crossover clinical trial comparing the prophylactic effects of candesartan and propranolol in 72 patients. Finapres noninvasive blood pressure curves were analyzed. On the descending limb of the pulse curve, a notch is produced by pulse wave reflection, and its relative height compared to the top of the curve (the notch ratio) was used as a marker of arterial wall stiffness.

Results:

Candesartan decreased the notch ratio from baseline ( p = 0.005), reflecting more compliant arteries and vasodilation, whereas propranolol increased the notch ratio ( p = 0.005), reflecting less compliant arteries and vasoconstriction. There was no difference in baseline notch ratio between clinical responders and nonresponders.

Conclusion:

The drugs are both efficient prophylactic medications, yet they have opposite effects on arterial wall dynamics. This suggests that drug effects other than those on arterial compliance must be responsible for their prophylactic effect in migraine.

Characterization of Rat Cardiovascular System by Anacrotic/Dicrotic Notches in the Condition of Increase/Decrease of NO Bioavailability

We characterized modes of action of NO-donor S-nitrosoglutathione (GSNO) and NO-synthase inhibitor l-NAME derived from dicrotic (DiN) and anacrotic (AnN) notches of rat arterial pulse waveform (APW) in the condition of increased/decreased NO bioavailability. The cross-relationship patterns of DiN and AnN with 34 hemodynamic parameters (HPs) induced by GSNO and l-NAME are presented. After GSNO bolus administration, approximate non-hysteresis relationships were observed in the difference between DiN-AnN (mmHg) blood pressure (BP) and other 19 HPs, suggesting that these HPs, i.e., their signaling pathways, responding to NO concentration, are directly connected. Hysteresis relationships were observed between DiN-AnN (mmHg) and other 14 HPs, suggesting that signaling pathways of these HPs are indirectly connected. The hysteresis relationships were only observed between the time interval DiN-AnN (ms) and other 34 HPs, indicating no direct connection of signaling pathways. The cross-relationship patterns of DiN-AnN (mmHg), but not DiN-AnN (ms), induced by l-NAME were in accordance to the increased NO bioavailability induced by GSNO. In conclusion, we found the non-hysteresis/hysteresis cross-relationship "patterns" of DiN-AnN intervals to other HPs in the presence of GSNO that revealed their direct or indirect signaling pathways connections. This may contribute to our understanding of biological effects of natural substances that modulate NO production and/or NO signaling pathways.

Patterns and Direct/Indirect Signaling Pathways in Cardiovascular System in the Condition of Transient Increase of NO

Aim

To study “patterns” and connections of signaling pathways derived from the rat arterial pulse waveform (APW) under the condition of transient NO increase.

Methods and Results

The right jugular vein of anesthetized Wistar rats was cannulated for administration of NO donor S-nitrosoglutathione. The left carotid artery was cannulated to detect APW. From rat APW, 35 hemodynamic parameters (HPs) and several their crossrelationships were evaluated. We introduced a new methodology to study “patterns” and connections of different signaling pathways, which are suggested from hysteresis and nonhysteresis crossrelationships of 35 rat HPs. Here, we show parallel time-dependent patterns of 35 HPs and some of their crossrelationships under the condition of transient increase of NO bioavailability by administration of S-nitrosoglutathione. Approximate nonhysteresis relationships were observed between systolic blood pressure and at least 11 HPs suggesting that these HPs, i.e., their signaling pathways, responding to NO concentration, are directly connected. Hysteresis relationships were observed between systolic blood pressure and at least 14 HPs suggesting that the signaling pathways of these HPs are indirectly connected. Totally, from the crossrelationships of 35 HPs, one can obtain 595 “patterns” and indication of direct or indirect connections between the signaling pathways.

Conclusion

We described the procedure leading virtually to 595 relationships, from which “patterns” for transient NO increase and direct or indirect connections of signaling pathways can be suggested. From a clinical perspective, this approach may be used in animal models and in humans to create a data bank of patterns of crossrelationships of HPs for different cardiovascular conditions. By comparison with unknown patterns of studied APW with the data bank patterns, it would be possible to determine cardiovascular conditions of the studied subject from the recorded arterial blood pressure. Additionally, it can help to find molecular mechanism of particular (patho-) physiological conditions or drug action and may have predictive or diagnostic value.

Changes of blood pressure following initiation of physical inactivity and after external addition of pulses to circulation

PURPOSE

To determine whether an innovative, motorized, wellness device that effortlessly produces physical activity (JD) can mitigate the hypertensive effects of prolonged sitting or lying down.

METHODS

Twenty-two normotensive and hypertensive adults of both genders gave informed consent to participate in a randomized controlled crossover study of a passive simulated jogging device (JD) in both supine and seated postures. Each study participant was monitored with a continuous non-invasive arterial pressure monitoring device (CNAP) over 60 min. The initial 10 min served as baseline for each posture. The subjects were randomized to begin with either JD or SHAM control for 30 min, and monitoring was continued for an additional 10 min in one posture; three days later posture and order of JD or SHAM were changed.

RESULTS

In both seated and supine postures, SHAM was associated with a significant rise in blood pressure (BP) which was observed within 5-10 min; it continued to rise or remain elevated for over a 40-min observation period. In contrast, JD produced a significant decrease in both systolic and diastolic blood pressure in both postures. During recovery in seated posture JD decreased systolic and diastolic BP by - 8.1 and - 7.6 mmHg, respectively. In supine posture, a similar decrease in BP occurred.

CONCLUSIONS

There is rapid onset of increase in systolic and diastolic BP with physical inactivity in both supine and seated postures. Administration of JD significantly decreased BP in both postures. Further studies are needed to assess long-term effectiveness.

Mathematical relationships and their consequences between rat pulse waveform parameters and blood pressure during decreasing NO bioavailability

NEW FINDINGS

What is the central question of this study? We wanted to find out whether the relationship between rat arterial pulse waveform (APW) parameters and blood pressure could be described by known mathematical functions and find mathematical parameters for conditions of hypertension resulting from decreased NO bioavailability. What is the main finding and its importance? We found mathematical functions and their parameters that approximate the relationships of 12 APW parameters to systolic and diastolic blood pressure in conditions of decreased NO bioavailability. The results may assign APW parameters to decreased NO bioavailability, which may have predictive or diagnostic value. Information obtained from the arterial pulse waveform (APW) is useful for characterization of the cardiovascular system in particular (patho)physiological conditions. Our goal was to find out whether the relationships between rat APW parameters could be described by simple mathematical functions and to find mathematical parameters for conditions of hypertension resulting from decreased NO bioavailability. Therefore, we explored details of 14 left carotid APW parameters of anaesthetized male Wistar rats and mathematically characterized their relationship to systolic and diastolic blood pressure (BP) in conditions of a gradual reduction in NO bioavailability after administration of l-NAME. The right jugular vein of anaesthetized Wistar rats was cannulated for l-NAME administration. The left carotid artery was cannulated to detect the APW at high resolution. Here, we show the time-dependent parallel changes of 14 APW parameters before and after i.v. administration of l-NAME and present mathematical functions that approximate the relationships of 12 APW parameters to systolic and diastolic BP. Some APW parameters had minor (e.g. heart rate) or biphasic dependence on BP (e.g. relative level of the maximum rate of ventricular pressure decrease (dP/dt_min )), but all relationships, within a particular range of BP, could be approximated by known regression functions, as a linear function (e.g. pulse BP), exponential decay (e.g. relative level of the maximum rate of ventricular pressure increase (dP/dt_max )), exponential growth (systolic area), exponential rise to a maximum (relative augmentation index) or sigmoid function (e.g. increase of relative level of dP/dt_min ). The mathematical functions may assign APW parameters to decreased NO bioavailability. This may have predictive or diagnostic value.

In vivo support for the new concept of pulmonary blood flow-mediated CO2 gas excretion in the lungs

To further examine the validity of the proposed concept of pulmonary blood flow-dependent CO2 gas excretion in the lungs, we investigated the effects of intramediastinal balloon catheterization-, pulmonary artery catheterization-, or isoprenaline (ISP)-induced changes in pulmonary blood flow on the end-expiratory CO2 gas pressure (PeCO2), the maximal velocity of the pulmonary artery (Max Vp), systemic arterial pressure, and heart rate of anesthetized rabbits. We also evaluated the changes in the PeCO2 in clinical models of anemia or pulmonary embolism. An almost linear relationship was detected between the PeCO2 and Max Vp. In an experiment in which small pulmonary arteries were subjected to stenosis, the PeCO2 fell rapidly, and the speed of the reduction was dependent on the degree of stenosis. ISP produced significant increases in the PeCO2 of the anesthetized rabbits. Conversely, treatment with piceatannol or acetazolamide induced significant reductions in the PeCO2. Treatment with a cell surface F1/FO ATP synthase antibody caused significant reductions in the PeCO2 itself and the ISP-induced increase in the PeCO2. Neither the PeCO2 nor SAP was significantly influenced by marked anemia [%hematocrit (Ht), 70∼47%]. On the other hand, in the presence of less severe anemia (%Ht: 100∼70%) both the PeCO2 and SAP fell significantly when the rabbits' blood viscosity was decreased. The rabbits in which pulmonary embolisms were induced demonstrated significantly reduced PeCO2 values, which was compatible with the lowering of their Max Vp. In conclusion, we reaffirm the validity of the proposed concept of CO2 gas exchange in the lungs.

Effect of whole-body periodic acceleration on exercise-induced muscle damage after eccentric exercise

PURPOSE

To examine the effects of whole-body periodic acceleration (pGz) on exercise-induced-muscle-damage (EIMD) -related symptoms induced by unaccustomed eccentric arm exercise.

METHODS

Seventeen active young men (23.4 ± 4.6 y) made 6 visits to the research facility over a 2-wk period. On day 1, subjects performed a 1-repetition-maximum (1RM) elbow-flexion test and were randomly assigned to the pGz (n = 8) or control group (n = 9). Criterion measurements were taken on day 2, before and immediately after performance of the eccentric-exercise protocol (10 sets, 10 repetitions using 120% 1RM) and after the recovery period. During subsequent sessions (24, 48, 72, and 96 h) these data were collected before pGz or passive recovery. Measurements included isometric strength (maximal voluntary contraction [MVC]), blood markers (creatine kinase, myoglobin, IL-6, TNF-α, TBARS, PGF2α, protein carbonyls, uric acid, and nitrites), soreness, pain, circumference, and range of motion (ROM).

RESULTS

Significantly higher MVC values were seen for pGz throughout the recovery period. Within-group differences were seen in myoglobin, IL-6, IL-10, protein carbonyls, soreness, pain, circumference, and ROM showing small negative responses and rapid recovery for the pGz condition.

CONCLUSION

Our results demonstrate that pGz can be an effective tool for the reduction of EIMD and may contribute to the training-adaptation cycle by speeding up the recovery of the body due to its performance-loss-lessening effect.

Decreased blood pressure with a corresponding decrease in adhesive molecules in diabetic rats caused by vitamin E administration

BACKGROUND

Hypertension is one of the important clinical problems of diabetic cardiovascular disease. The aim of this study was to determine the effect of vitamin E on blood pressure parameters and adhesive molecule amounts in diabetic rats.

METHODS

Twenty-four male Wistar rats were divided into three groups (each of n = 8): the controls (C), non-treated diabetic (NTD), and vitamin E treated diabetic (VETD) groups. A single intraperitoneal injection of buffered streptozotocin (60 mg/kg) in cold sodium citrate (pH 4.5) was used to induce diabetes. The VETD group received 300 mg of vitamin E daily intragastrically for 6 weeks. Systolic and diastolic blood pressure, mean arterial pressure, as well as the dicrotic pressure, crest time, systolic and diastolic periods, and plasma levels of intercellular adhesion molecule-1 and E-selectin were measured after 6 weeks.

RESULTS

The results revealed that there was a significant increase in systolic and diastolic blood pressures, mean arterial pressure, crest time, systolic duration, and the amount of sICAM-1 and E-selectin in diabetic rats. There was no significant difference in the heart rate or cardiac cyclic duration among the different groups. Significant improvement of blood pressure parameters as well as attenuation of the elevated ICAM-1 and E-selectin amounts was found in the vitamin E treated group.

CONCLUSIONS

These findings indicate that vitamin E significantly improved blood pressure elevation in diabetic rats and that these effects could be associated with reducing adhesive molecule and antioxidant properties of vitamin E.

Modelling pulse wave propagation in the rabbit systemic circulation to assess the effects of altered nitric oxide synthesis

Pulse wave propagation in the mature rabbit systemic circulation was simulated using the one-dimensional equations of blood flow in compliant vessels. A corrosion cast of the rabbit circulation was manufactured to obtain arterial lengths and diameters. Pulse wave speeds and inflow and outflow boundary conditions were derived from in vivo data. Numerical results captured the main features of in vivo pressure and velocity pulse waveforms in the aorta, brachiocephalic artery and central ear artery. This model was used to elucidate haemodynamic mechanisms underlying changes in peripheral pulse waveforms observed in vivo after administering drugs that alter nitric oxide synthesis in the endothelial cells lining blood vessels. According to our model, these changes can be explained by single or combined alterations of blood viscosity, peripheral resistance and compliance, and the elasticity of conduit arteries.

Low-amplitude pulses to the circulation through periodic acceleration induces endothelial-dependent vasodilatation

Low-amplitude pulses to the vasculature increase pulsatile shear stress to the endothelium. This activates endothelial nitric oxide (NO) synthase (eNOS) to promote NO release and endothelial-dependent vasodilatation. Descent of the dicrotic notch on the arterial pulse waveform and a-to-b ratio (a/b; where a is the height of the pulse amplitude and b is the height of the dicrotic notch above the end-diastolic level) reflects vasodilator (increased a/b) and vasoconstrictor effects (decreased a/b) due to NO level change. Periodic acceleration (pG(z)) (motion of the supine body head to foot on a platform) provides systemic additional pulsatile shear stress. The purpose of this study was to determine whether or not pG(z) applied to rats produced endothelial-dependent vasodilatation and increased NO production, and whether the latter was regulated by the Akt/phosphatidylinositol 3-kinase (PI3K) pathway. Male rats were anesthetized and instrumented, and pG(z) was applied. Sodium nitroprusside, N(G)-nitro-l-arginine methyl ester (l-NAME), and wortmannin (WM; to block Akt/PI3K pathway) were administered to compare changes in a/b and mean aortic pressure. Descent of the dicrotic notch occurred within 2 s of initiating pG(z). Dose-dependent increase of a/b and decrease of mean aortic pressure took place with SNP. l-NAME produced a dose-dependent rise in mean aortic pressure and decrease of a/b, which was blunted with pG(z). In the presence of WM, pG(z) did not decrease aortic pressure or increase a/b. WM also abolished the pG(z) blunting effect on blood pressure and a/b of l-NAME-treated animals. eNOS expression was increased in aortic tissue after pG(z). This study indicates that addition of low-amplitude pulses to circulation through pG(z) produces endothelial-dependent vasodilatation due to increased NO in rats, which is mediated via activation of eNOS, in part, by the Akt/PI3K pathway.