Chronic administration of interferon-α decreases blood pressure and heart rate in rats

We studied the effects of interferon-α on rat cardiovascular system. Intravenous administration of intron-A in a dose of 100,000 IU/kg for 3 days led to a permanent and statistically significant decrease in blood pressure (on days 2 and 3) and reduction in heart rate. These effects were not associated with changes in baroreflex regulation of the cardiovascular system. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 129, No. 5, pp. 491–495, May, 2000     

Effect of β-carotene on the development of adjuvant-induced arthritis and production of interleukin-1 in rats

Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 116, N ^o 12, pp. 611–613, December 1993     

Does motor activity during psychophysiological paradigms confound the quantification and interpretation of heart rate and heart rate variability measures in young children?

Respiratory sinus arrhythmia (RSA), heart period, and motor activity were monitored in preschoolers during a variety of tasks varying in required movement. The data analyses indicate: (1) that when activity increases during tasks, there are synchronous decreases in heart period and RSA; (2) that correlations between changes in RSA and heart period are related to activity only during exercise when there is a major demand for increased metabolic resources; and (3) that the covariation among the variables within each condition is low except during exercise. These findings suggest that the slight increases in motor activity (i.e., hand movements) often required in attention demanding psychophysiological protocols are not related to RSA and heart period responses. However, when tasks necessitate large increases in motor activity (e.g., exercise), the decreases in heart period and RSA are related to the change in motor activity.     

Estimation of maximal heart rate using the relationship between heart rate variability and exercise intensity in 40–67 years old men

Large interindividual variation in maximal heart rate (HR_max) may not be accounted for by age alone. In order to evaluate a novel method in the prediction of HR_max, this study examined the profile of HR variability (HRV) during exercise in 40–67 years old men (n = 74). R–R intervals were recorded during supine rest and during a graded exercise test by cycle ergometry until exhaustion. A third-degree polynomial function was fitted to the HRV data recorded during exercise to represent the HRV profile of each subject. The instantaneous beat-to-beat R–R interval variability (SD1), high (HF) and low frequency power decreased between all consecutive exercise intensities (P < 0.033). The relationship between HR_max and a variable illustrating the declining rate of HF (HR_HF50%) was stronger (r = 0.50, P < 0.001) than between HR_max and age (r = −0.36, P < 0.01). The regression analysis showed that a more accurate estimation of HR_max was attained when HRV was used in the equation in addition to age: HR_max = 160.633–0.603(age) + 0.441(HR_HF50%) (SEE = 9.8 bpm vs. 11.6 bpm in the equation based on age alone). The decline of HRV during incremental exercise seems to be useful for accurate estimation of maximal heart rate.     

Effort—reward imbalance,heart rate,and heart rate variability: the cardiovascular risk in young finns study

Background: Work stress indicated by effort—reward imbalance is hypothesized to cause autonomic arousal, which, if prolonged or frequent, could contribute to cardiovascular pathology. However, only limited empirical evidence on this mechanism is available. Purpose: This study examined associations between effort-reward imbalance, heart rate (HR), and heart rate variability (HRV). Method: The participants were 457 women and 406 men (mean age 32.3 years) derived from the population-based Young Finns Study. Effort—reward imbalance was defined as the ratio between effort and reward, higher efforts compared to rewards indicating greater imbalance. Results: In age-adjusted regression models, higher effort-reward imbalance was associated with lower HRV, and lower reward was associated with higher HR among women. These associations were not attenuated after additional adjustments for demographic characteristics and coronary risk factors. No significant associations of effort—reward imbalance or its components with HR and HRV were found in men. Conclusion: Our finding of lower HRV and higher HR in young healthy women with high effort—reward imbalance and low rewards provides evidence of a potential mechanism that may link effort-reward imbalance to the development of coronary heart disease (CHD) in women.     

Effect of β-hydroxy-β-methylbutyrate in masticatory muscles of rats

The aim of this research was to examine the influence of β-hydroxy-β-methylbutyrate (HMB) on changes in the profile of muscle fibers, whether these alterations were similar between the elevator and depressor muscles of the jaw, and whether the effects would be similar in male and female animals. Fifty-eight rats aged 60 days (29 animals of each gender) were divided into four groups: the initial control group (ICG) was sacrificed at the beginning of the experiment; the placebo control group (PCG) received saline and was fed ad libitum; the experimental group (EG) received 0.3 g kg⁻¹ of HMB daily for 4 weeks by gavage as well as the same amount of food consumed by the PCG in the previous day; and the experimental ad libitum group (EAG) received the same dose of the supplement along with food ad libitum. Samples included the digastric and masseter muscles for the histoenzymological analysis. Data were subjected to statistical analysis with a significance level of P < 0.05. Use of HMB caused a decrease in the percentage of fast twitch glycolytic (FG) fibers and an increase in fast twitch oxidative glycolytic (FOG) fibers in males in both experimental groups (EG and EAG). However, it produced no increase in the muscle fiber area, in either gender, in the masseter muscle. In the digastric muscle, the HMB did not change the frequency or the area of any muscle fiber types in either gender. Our data suggest that the use of HMB caused small changes in the enzymological profile of fibers of the mastication muscles; the changes were different in the elevator and depressor muscles of the jaw and the results were different depending on gender.     

Effect of β-carotene on the plasma membrane lipids in chronically γ-irradiated rats

Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 116, N ^o 10, pp. 370–374, October, 1993     

Does preprocessing change nonlinear measures of heart rate variability?

This work investigated if methods used to produce a uniformly sampled heart rate variability (HRV) time series significantly change the deterministic signature underlying the dynamics of such signals and some nonlinear measures of HRV. Two methods of preprocessing were used: the convolution of inverse interval function values with a rectangular window and the cubic polynomial interpolation. The HRV time series were obtained from 33 Wistar rats submitted to autonomic blockade protocols and from 17 healthy adults. The analysis of determinism was carried out by the method of surrogate data sets and nonlinear autoregressive moving average modelling and prediction. The scaling exponents , ₁ and ₂ derived from the detrended fluctuation analysis were calculated from raw HRV time series and respective preprocessed signals. It was shown that the technique of cubic interpolation of HRV time series did not significantly change any nonlinear characteristic studied in this work, while the method of convolution only affected the ₁ index. The results suggested that preprocessed time series may be used to study HRV in the field of nonlinear dynamics.     

Effect of Cornus officinalis glycoside on adjuvant-induced arthritis in rats

The aim of this study was to explore the effect of Cornus officinalis glucosides (COG) on adjuvant-induced arthritis in rats and its mechanism. Seventy-two rats were divided into six groups of normal, model, Dexasone (0.125 mg/kg), high-dose COG (240 mg/kg), mid-dose COG (120 mg/kg), and low-dose COG (60 mg/kg). Rat arthritis was induced by injection of Freund's complete adjuvant in the hind paws. All treatment started from the day the arthritis was induced. The edema degree of the adjuvant injection location was determined on days 1, 3, 5, 7, 9, 11, 13, 15, 17, 20, 23 and the opposite side was observed on days 11, 13, 15, 17, 20, 23 after the injection of adjuvant. All rats were sacrificed on day 24 after the injection of adjuvant for microscopic examination of the ankle, and for the study of the immunological molecular mechanism. The results showed that the COG significantly suppressed both the primary and secondary edema, improved pathological injuries of adjuvant arthritis (AA) rat ankles, significantly suppressed the proliferation of T lymphocytes and DTH reaction. It significantly suppressed IL-1, IL-6 and TNF-αproduction from peritoneal macrophages and PGE2 in plasma. In conclusion, the Cornus officinalis glucosides (COG) is able to prevent and cure the rat adjuvant-induced arthritis, and can suppress the production of pro-inflammatory cytokine IL-1, IL-6, TNF-αand PGE2.     

Correlation among Poincare´plot indexes and time and frequency domain measures of heart rate variability

Primary objective: In order to corroborate the reported performance advantage of Poincar´eplot indexes as autonomic activity markers, the correlation among these indexes and those computed from the time and frequency domains were obtained. Methods and procedures: Starting from the RR series derived from the ECG of 21 healthy volunteers during five manoeuvres, longitudinal (L), transverse (T) axis, and autocorrelation (r) from Poincar´eplots, rMSSD and standard deviation (SD) in the temporal domain, and frequency domain indexes were computed. Main outcomes and results: Poincar´e plot indexes were correlated in a better way with the time indexes, rather than the spectral measures. A strong correlation (0.997) between L and SD was observed, while an underlying mathematical relationship was established for T vs rMSSD. Conclusions: Poincaré plot indexes may be considered as equivalent or surrogates of the temporal ones, and they do not have a better performance as autonomic markers.     

Effect of mode and schedule of administration on carcinogenic effect of N-methyl-N′-nitro-N-nitrosoguanidine in rats

Laboratory of Methods of Carcinogen Screening, Research Institute of Carcinogenesis, All-Union Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Trapeznikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 109, No. 2, pp. 175–176, February, 1990.     

Correlation among Poincaré plot indexes and time and frequency domain measures of heart rate variability.

PRIMARY OBJECTIVE: In order to corroborate the rported performance advantage of Poincaré plot indexes as autonomic activity markers, the correlation among these indexes and those computed from the time and frequency domains were obtained. METHODS AND PROCEDURES: Starting from the RR series derived from the ECG of 21 healthy volunteers during five manoeuvres, longitudinal (L), transverse (T) axis, and autocorrelation (r) from Poincaré plots, rMSSD and standard deviation (SD) in the temporal domain, and frequency domain indexes were computed. MAIN OUTCOMES AND RESULTS: Poincaré plot indexes were correlated in a better way with the time indexes, rather than the spectral measures. A strong correlation (0.997) between L and SD was observed, while an underlying mathematical relationship was established for T vs rMSSD. CONCLUSIONS: Poincaré plot indexes may be considered as equivalent or surrogates of the temporal ones, and they do not have a better performance as autonomic markers.     

Effect of T3 treatment on the response to ischemia–reperfusion of heart preparations from sedentary and trained rats

We investigated whether swim training modifies the effect of T₃ treatment on rat heart response to ischemia–reperfusion. Homogenates of Langendorff preparations perfused for 25 min after 20-min ischemia were used for biochemical determinations and isolation of mitochondrial fractions. Oxidative damage and antioxidant levels of homogenates, O₂ consumption and H₂O₂ release rates, oxidative damage, and susceptibility to Ca²⁺-induced swelling of mitochondria were determined. During reperfusion, hyperthyroid hearts displayed significant tachycardia and low inotropic recovery. This pattern was improved by training, which also attenuated tissue oxidative damage and glutathione depletion. Similar training effects were shown in euthyroid preparations. Moreover, training reduced mitochondrial H₂O₂ production and oxidative damage in hyperthyroid and euthyroid hearts and susceptibility to Ca²⁺-induced swelling only in the hyperthyroid ones. Rates of mitochondrial O₂ consumption were not different in sedentary and trained hyperthyroid rats. However, determination of the oxidative capacity suggested that, in the sedentary rats, O₂ consumption was conditioned by oxidative damage mitochondria have suffered, whereas in trained rats, it was due to changes in mitochondrial characteristics. The above results suggest that moderate training is able to reduce hyperthyroid heart susceptibility to oxidative damage and dysfunction modifying mitochondrial population.     

Quantitative Poincaré plot analysis of heart rate variability: effect of endurance training

The aim of the study was to evaluate the effectiveness of the Poincaré plot analysis of heart rate variability (HRV) in observing endurance training-induced changes. Four 10-min manoeuvres were performed (supine lying, standing, steady state exercising and subsequent recovery) by eight control subjects before and after a short-term endurance training and by eight subjects trained for at least 3 years. HRV was assessed by traditional time- and frequency-domain indexes, in parallel with the Poincaré plot analysis. In the latter each R-R interval is plotted as a function of the previous one, and the standard deviations of the instantaneous and long-term R-R interval variability are calculated. In our subjects, the Poincaré scatter grams became gradually narrower from supine to exercising, with progressive parasympathetic withdrawal. Short- and long-term endurance training led to higher aerobic power (p<0.05) and ventilatory threshold shifted towards higher power output (p<0.05). All HRV evaluation methods showed that HRV values were higher after training both during supine lying and standing (p<0.05). The Poincaré scatter grams were wider in the trained state. Standard deviations of the Poincaré plot were significantly correlated with the main parameters of the time- and frequency-domain analyses, especially concerning the parasympathetic indicators. These results suggested that Poincaré plot parameters as well as the "width" of the scatter gram could be considered as surrogates of time- and frequency-domain analysis to assess training-induced changes in HRV.     

Survival of rats with experimental chronic heart failure depending on pharmacodynamic and pharmacokinetic parameters of angiotensin-converting enzyme inhibitors and β-adrenoceptor blockers

Lipophilic inhibitors of angiotensin-converting enzyme increased 6-month survival and/or lifetime of rats with experimental chronic heart failure. These drugs had no effect on the mortality rate of animals with acute decompensation of the disease. β-Adrenoceptor blockers without intrinsic sympathomimetic activity not only prolonged 6-month survival and lifetime, but also decreased the mortality rate of rats with decompensation of chronic heart failure. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 1, pp. 45–48, January, 2006     

Musculoskeletal overuse injuries and heart rate variability: Is there a link?

Accurate detection and prevention of overuse musculoskeletal injuries is limited by the nature of somatic tissue injury. In the pathogenesis of overuse injuries, it is well recognized that an abnormal inflammatory response occurs within somatic tissue before pain is perceived which can disrupt the normal remodeling process and lead to subsequent degeneration. Current overuse injury prevention methods focused on biomechanical faults or performance standards lack the sensitivity needed to identify the status of tissue injury or repair. Recent evidence has revealed an apparent increase in the prevalence and impact of overuse musculoskeletal injuries in athletics. When compared to acute injuries, overuse injuries have a potentially greater negative impact on athletes’ overall health burden. Further, return to sport rehabilitation following overuse injury is complicated by the fact that the absence of pain does not equate to complete physiological healing of the injured tissue. Together, this highlights the need for exercise monitoring and injury prevention methods which incorporate assessment of somatic tissue response to loading. One system primarily involved in the activation of pathways and neuromediators responsible for somatic tissue repair is the autonomic nervous system (ANS). Although not completely understood, emerging research supports the critical importance of peripheral ANS activity in the health and repair of somatic tissue injury. Due to its significant contributions to cardiac function, ANS activity can be measured indirectly with heart rate monitoring. Heart rate variability (HRV) is one index of ANS activity that has been used to investigate the relationship between athletes’ physiological response to accumulating training load. Research findings indicated that HRV may provide a reflection of ANS homeostasis, or the body’s stress-recovery status. This noninvasive marker of the body’s primary driver of recovery has the potential to incorporate important and as yet unmonitored physiological mechanisms involved in overuse injury development. We hypothesize that abnormal somatic tissue response to accumulating microtrauma may modulate ANS activity at the level of HRV. Exploring the link between HRV modulation and somatic tissue injury has the potential to reveal the putative role of ANS homeostasis on overuse musculoskeletal injury development.