scholarly journals Severe spontaneous bradycardia associated with respiratory disruptions in rat pups with fewer brain stem 5-HT neurons

2009 ◽  
Vol 296 (6) ◽  
pp. R1783-R1796 ◽  
Author(s):  
Kevin J. Cummings ◽  
Kathryn G. Commons ◽  
Kenneth C. Fan ◽  
Aihua Li ◽  
Eugene E. Nattie
Keyword(s):  
Heart Rate ◽  
Metabolic Rate ◽  
Breathing Pattern ◽  
Neonatal Period ◽  
Vehicle Control ◽  
Accurate Assessment ◽  
Breathing Frequency ◽  
Cardiorespiratory Control ◽  
Rat Pups ◽  
Novel Method

The medullary 5-HT system has potent effects on heart rate and breathing in adults. We asked whether this system mitigates the respiratory instability and bradycardias frequently occurring during the neonatal period. 5,7-Dihydroxytryptamine (5,7-DHT) or vehicle was administered to rat pups at postnatal day 2 (P2), and we then compared the magnitude of bradycardias occurring with disruptions to eupnea in treated and vehicle control littermates at P5–6 and P10–12. We then used a novel method that would allow accurate assessment of the ventilatory and heart rate responses to near square-wave challenges of hypoxia (10% O2), hypercapnia (5 and 8% CO2 in normoxia and hyperoxia), and asphyxia (8% CO2-10% O2), and to the induction of the Hering-Breuer inflation reflex (HBR), a potent, apnea-inducing reflex in newborns. The number of 5-HT-positive neurons was reduced ∼80% by drug treatment. At both ages, lesioned animals had considerably larger bradycardias during brief apnea; at P5–6, average and severe events were ∼50% and 70% greater, respectively, in lesioned animals ( P = 0.002), whereas at P10–12, events were ∼ 23% and 50% greater ( P = 0.018). However, lesioning had no effect on the HR responses to sudden gas challenge or the HBR. At P5–6, lesioned animals had reduced breathing frequency and ventilation (V̇e), but normal V̇e relative to metabolic rate (V̇e/V̇o2). At P10–12, lesioned animals had a more unstable breathing pattern ( P = 0.04) and an enhanced V̇e response to moderate hypercapnia ( P = 0.007). Within the first two postnatal weeks, the medullary 5-HT system plays an important role in cardiorespiratory control, mitigating spontaneous bradycardia, stabilizing the breathing pattern, and dampening the hypercapnic V̇e response.

Ergonomic Considerations of Fin Size for Working Divers

1982 ◽  
Vol 26 (6) ◽  
pp. 525-529 ◽  
Author(s):  
I. B. Mekjavic ◽  
P. A. Rowe ◽  
J. B. Morrison
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Cardiovascular System ◽  
Surface Area ◽  
Minute Ventilation ◽  
Metabolic Cost ◽  
Breathing Frequency ◽  
Work Period ◽  
Ventilatory Volume

Four divers conducted two identical work protocols, consisting of swimming against a graded resistance on an underwater ergometer at a depth of ten feet. In one protocol the divers used fins each having a surface area of 540 cm2 and in the second protocol they used fins whose surface area was 940 cm2. Oxygen consumption, heart rate, ventilation, breathing frequency and kick rate were monitored throughout the twenty minute work period. The 540 cm2 fins demanded a siqnificantly higher metabolic rate than the 940 cm2 fins (50.85 ± 1.54 compared to 46.99 ± 1.52 ml.min.-1.kg-1). The smaller fins also elicited higher heart rates (171.8 ± 4.3 min.-1) than the larger fins (142.5 ± 8.7 min.-1) and induced a higher kicking frequency than was required with the larger fins (43 ± 4 min.-1 and 32 ± 1 min.-1 respectively). Ventilatory volume at the end of the final workload was 128.6 ± 7 1/min. with small fins and 111.1 ± 6.5 1/min. with large fins. These data suggest that the larger fins are more economical in terms of minute ventilation and metabolic cost and are less demanding on the cardiovascular system. Subjectively, the larger fins were perceived as less fatiguing than the smaller fins.

Some consequences of body size

1984 ◽  
Vol 247 (4) ◽  
pp. H495-H507 ◽  
Author(s):  
L. E. Ford
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Metabolic Rate ◽  
Muscle Power ◽  
Weight Ratio ◽  
Single Species ◽  
Hill Climbing ◽  
Proper Size ◽  
Higher Power ◽  
Metabolic Indices

The question of the proper size denominator for metabolic indices is addressed. Metabolic rate among different species is proportional to the 3/4 power of body weight, not surface area. Muscle power also varies with the 3/4 power of weight, suggesting that metabolic rate is determined mainly by muscle power. Power-to-weight ratio, specific metabolic rate, and a number of metabolic periods, including heart rate, all vary inversely with the 1/4 power of body weight. Thus the relative times required for physiological and pathological processes in different species may be estimated from the average resting heart rate for the species. There are not many small humans among athletic record holders in events involving acceleration and hill climbing, as would be expected if they had higher power-to-weight ratios. Thus the relationship between size and metabolic rate in different species should not be applied within the single species of humans. Evidence is reviewed showing that basal metabolic rate in humans is determined mainly by lean body mass.

Respiratory Metabolism During Pregnancy in the Guinea Pig

1957 ◽  
Vol 190 (3) ◽  
pp. 425-428 ◽  
Author(s):  
Richard M. Hoar ◽  
William C. Young
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Guinea Pig ◽  
Metabolic Rate ◽  
Adrenal Cortex ◽  
Guinea Pigs ◽  
Sharp Decrease ◽  
Zona Fasciculata ◽  
Respiratory Metabolism ◽  
Morphological Differences

Oxygen consumption and heart rate during pregnancy were measured in untreated, thyroxin-injected and thyroidectomized guinea pigs given I131. From impregnation until parturition, oxygen consumption increased 7.9% in untreated females. The increase continued until 5 days postpartum when a sharp decrease occurred. The increase is not accounted for by growth of the fetal mass. Comparable increases occurred in thyroxin-injected (16.2%) and thyroidectomized (11.9%) females, although the levels throughout were higher and lower, respectively, than in intact females. Heart rate did not increase. On the contrary, statistically significant decreases occurred in the untreated and thyroxin-injected females. Although the mechanism associated with the increased metabolic rate is not known, the possibility of thyroid participation would seem to be excluded. Involvement of the adrenal cortex is suggested by morphological differences in the cells of the zona fasciculata in pregnant and nonpregnant females and by evidence cited from other studies.

scholarly journals Monitoring of physiological and blood parameters during perinatal and neonatal period in calves

2010 ◽  
Vol 62 (1) ◽  
pp. 1-12 ◽  
Author(s):  
G. Piccione ◽  
S. Casella ◽  
P. Pennisi ◽  
C. Giannetto ◽  
A. Costa ◽  
...  
Keyword(s):  
Heart Rate ◽  
Respiratory Rate ◽  
Total Cholesterol ◽  
Rectal Temperature ◽  
Neonatal Period ◽  
Blood Parameters ◽  
External Jugular Vein ◽  
Individual Values ◽  
Functional Development ◽  
Adaptation Processes

Rectal temperature, heart and respiratory rates, and the course of some blood parameters were monitored in calves during perinatal and neonatal periods. The study was carried out on eight Limousine calves. From all subjects, rectal temperature, heart rate, and respiratory rate were measured. Blood samples were taken at the same hour (9am) from the external jugular vein, and then centrifuged and stored until analyses. By means of an UV spectrophotometer, the following blood parameters were assessed for each subject: total protein, total cholesterol, triglycerides, glucose, non-esterified fatty acids (NEFA), urea, creatinine, cholinesterase, lactate dehydrogenase (LDH), hydroxybutirate, glutamate pyruvate transaminases (GPT), glutamate oxalacetate transaminases (GOT), direct and total bilirubin, magnesium, iron, potassium, phosphorus, chloride and sodium. The results showed a significant effect of days of life (P<0.05) only on total cholesterol, creatinine and GOT during the first week of life and a significant effect of days of life on rectal temperature, heart rate, respiratory rate, total cholesterol, NEFA, creatinina, and GOT during the first month of life. A correlation among individual values for postnatal age (days of life) and heart rate in calves during the first month of life was observed. In conclusion, modifications of studied parameters could be attributed to functional development of calves in neonatal period and contribute to the knowledge of adaptation processes in calf during the first week and the first month of life resulting useful for the diagnosis and treatment of any neonatal diseases.

scholarly journals Feasibility Assessment of Wearable Respiratory Monitors for Ambulatory Inhalation Topography

2021 ◽  
Vol 18 (6) ◽  
pp. 2990
Author(s):  
Shehan Jayasekera ◽  
Edward Hensel ◽  
Risa Robinson
Keyword(s):  
Risk Assessment ◽  
Heart Rate ◽  
Breathing Frequency ◽  
Exposure Risk ◽  
Analysis Software ◽  
Toxicant Exposure ◽  
Motion Data ◽  
Feasibility Assessment ◽  
Cardiopulmonary Performance ◽  
Exposure Risk Assessment

Background: Natural environment inhalation topography provides useful information for toxicant exposure, risk assessment and cardiopulmonary performance. Commercially available wearable respiratory monitors (WRMs), which are currently used to measure a variety of physiological parameters such as heart rate and breathing frequency, can be leveraged to obtain inhalation topography, yet little work has been done. This paper assesses the feasibility of adapting these WRMs for measuring inhalation topography. Methods: Commercially available WRMs were compiled and assessed for the ability to report chest motion, data analysis software features, ambulatory observation capabilities, participant acceptability, purchasing constraints and affordability. Results: The following WRMs were found: LifeShirt, Equivital EQ02 LifeMonitor, Smartex WWS, Hexoskin Smart Garment, Zephyr BioHarness, Nox T3&A1, BioRadio, SleepSense Inductance Band, and ezRIP & zRIP Durabelt. None of the WRMs satisfied all six assessment criteria in a manner enabling them to be used for inhalation topography without modification and development. Conclusions: The results indicate that there are WRMs with core technologies and characteristics that can be built upon for ambulatory inhalation topography measurement in the NE.

Unrestrained video-assisted plethysmography: a noninvasive method for assessment of lung mechanical function in small animals

2008 ◽  
Vol 104 (1) ◽  
pp. 253-261 ◽  
Author(s):  
Jason H. T. Bates ◽  
John Thompson-Figueroa ◽  
Lennart K. A. Lundblad ◽  
Charles G. Irvin
Keyword(s):  
Airway Resistance ◽  
Breathing Pattern ◽  
Small Animals ◽  
Mechanical Function ◽  
Direct Link ◽  
Breathing Frequency ◽  
Noninvasive Method ◽  
Noninvasive Methods ◽  
Mean Values ◽  
Video Assisted

The assessment of lung mechanical function in small animals, particularly mice, is essential for investigations into the pathophysiology of pulmonary disease. The most accurate and specific methods for making this assessment are highly invasive and so provide data of questionable relevance to normality. By contrast, present noninvasive methods based on unrestrained plethysmography have no direct link to the mechanical properties of the lung. There is thus a need for a completely noninvasive method for determining lung mechanical function in small animals. In the present study, we demonstrate an extension of unrestrained plethysmography in which changes in lung volume are estimated via orthogonal video imaging of the thorax. These estimates are combined with the pressure swings recorded as mice breathe inside a heated and humidified chamber to yield an estimate of specific airway resistance (sRaw). We used this new technique, which we term “unrestrained video-assisted plethysmography” (UVAP), to measure sRaw in 11 BALB/c mice exposed to aerosols of saline, methacholine, and albuterol and obtained mean values of 0.71, 1.23 and 1.10 cmH2O·s, respectively. Mean breathing frequency was 4.3, 3.4, and 3.6 breaths/s, respectively, while the corresponding mean tidal volumes were 0.36, 0.44 and 0.37 ml, respectively. We conclude that UVAP, a noninvasive method, is able to provide usefully accurate estimates of sRaw and breathing pattern parameters in mice.

On the fractal nature of heart rate variability in humans: effects of respiratory sinus arrhythmia

1995 ◽  
Vol 269 (2) ◽  
pp. H480-H486 ◽  
Author(s):  
Y. Yamamoto ◽  
J. O. Fortrat ◽  
R. L. Hughson
Keyword(s):  
Heart Rate ◽  
Time Series ◽  
Heart Rate Variability ◽  
Coarse Graining ◽  
Resting Heart Rate ◽  
Breathing Frequency ◽  
Fractal Nature ◽  
Sinus Arrhythmia ◽  
Spectral Exponent ◽  
Random Fractal

The purpose of the present study was to investigate the basic fractal nature of the variability in resting heart rate (HRV), relative to that in breathing frequency (BFV) and tidal volume (TVV), and to test the hypothesis that fractal HRV is due to the fractal BFV and/or TVV in humans. In addition, the possible fractal nature of respiratory volume curves (RVC) and HRV was observed. In the first study, eight subjects were tested while they sat quietly in a comfortable chair for 60 min. Beat-to-beat R-R intervals, i.e., HRV, and breath-by-breath BFV and TVV were measured. In the second study, six subjects were tested while they were in the supine position for 20-30 min. The RVC was monitored continuously together with HRV. Coarse-graining spectral analysis (Yamamoto, Y., and R. L. Hughson, Physica D 68: 250-264, 1993) was applied to these signals to evaluate the percentage of random fractal components in the time series (%Fractal) and the spectral exponent (beta), which characterizes irregularity of the signals. The estimates of beta were determined for each variable only over the range normally used to evaluate HRV. Values for %Fractal and beta of both BFV and TVV were significantly (P < 0.05) greater than those for HRV. In addition, there was no significant (P > 0.05) correlation between the beta values of HRV relative to either BFV (r = 0.14) or TVV (r = 0.34). RVC showed a smooth oscillation as compared with HRV; %Fractal for RVC (42.3 +/- 21.7%, mean +/- SD) was significantly (P < 0.05) lower than that for HRV (78.5 +/- 4.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

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