Effect of chronic sodium cyanate administration on O2 transport and uptake in hypoxic and normoxic exercise

1999 ◽  
Vol 86 (4) ◽  
pp. 1257-1263 ◽  
Author(s):  
Web McCanse ◽  
Kyle Henderson ◽  
Tetsuya Urano ◽  
Ichiro Kuwahira ◽  
Richard L. Clancy ◽  
...  
Keyword(s):  
Maximal Exercise ◽  
Ventilatory Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Saturation Pressure ◽  
Relative Magnitude ◽  
Pulmonary Vasoconstriction ◽  
O2 Transport ◽  
Hb Concentration ◽  
Response To Exercise ◽  
Sodium Cyanate

Systemic O2 transport during maximal exercise at different inspired [Formula: see text]([Formula: see text]) values was studied in sodium cyanate-treated (CY) and nontreated (NT) rats. CY rats exhibited increased O2affinity of Hb (exercise O2half-saturation pressure of Hb = 27.5 vs. 42.5 Torr), elevated blood Hb concentration, pulmonary hypertension, blunted hypoxic pulmonary vasoconstriction, and normal ventilatory response to exercise. Maximal rate of convective O2 transport was higher and tissue O2extraction was lower in CY than in NT rats. The relative magnitude of these opposing changes, which determined the net effect of cyanate on maximal O2 uptake (V˙o 2 max), varied at different [Formula: see text]:V˙o 2 max(ml ⋅ min−1 ⋅ kg−1) was lower in normoxia (72.8 ± 1.9 vs. 81.1 ± 1.2), the same at 70 Torr [Formula: see text] (55.4 ± 1.4 vs. 54.1 ± 1.4), and higher at 55 Torr[Formula: see text] (48 ± 0.7 vs. 40.4 ± 1.9) in CY than in NT rats. The beneficial effect of cyanate on V˙o 2 max at 55 Torr [Formula: see text] disappeared when Hb concentration was lowered to normal. It is concluded that the effect of cyanate on V˙o 2 maxdepends on the relative changes in blood O2 convection and tissue O2 extraction, which vary at different [Formula: see text]. Although uptake of O2 by the blood in the lungs is enhanced by cyanate, its release at the tissues is limited, probably because of a reduction in the capillary-to-tissue[Formula: see text] diffusion gradient secondary to the increased O2 affinity of Hb.

Acute vs. chronic effects of elevated hemoglobin O2 affinity on O2 transport in maximal exercise

2000 ◽  
Vol 89 (1) ◽  
pp. 265-272 ◽  
Author(s):  
Kyle K. Henderson ◽  
Web McCanse ◽  
Tetsuya Urano ◽  
Ichiro Kuwahira ◽  
Richard Clancy ◽  
...  
Keyword(s):  
Maximal Exercise ◽  
Saturation Pressure ◽  
Relative Magnitude ◽  
Extraction Ratio ◽  
Negative Effects ◽  
Arterial Blood ◽  
Group 3 ◽  
Group 2 ◽  
Sodium Cyanate ◽  
Group 1

These studies were conducted to compare the effects on systemic O2 transport of chronically vs. acutely increased Hb O2 affinity. O2 transport during maximal normoxic and hypoxic [inspired Po 2(Pi O2 ) = 70 and 55 Torr, respectively] exercise was studied in rats with Hb O2 affinity that was increased chronically by sodium cyanate ( group 1) or acutely by transfusion with blood obtained from cyanate-treated rats ( group 2). Group 3 consisted of normal rats. Hb O2 half-saturation pressure (P50; Torr) during maximal exercise was ∼26 in groups 1 and 2 and ∼46 in group 3. In normoxia, maximal blood O2 convection (T˙o 2 max = cardiac output × arterial blood O2 content) was similar in all groups, whereas in hypoxia T˙o 2 max was significantly higher in groups 1 and 2 than in group 3. Tissue O2 extraction (arteriovenous O2 content/arterial O2 content) was lowest in group 1, intermediate in group 2, and highest in group 3 ( P < 0.05) at all exercise Pi O2 values. In normoxia, maximal O2 utilization (V˙o 2 max) paralleled O2extraction ratio and was lowest in group 1, intermediate in group 2, and highest in group 3( P < 0.05). In hypoxia, the lower O2extraction ratio values of groups 1 and 2 were offset by their higher T˙o 2 max; accordingly, their differences inV˙o 2 max from group 3 were attenuated or reversed. Tissue O2 transfer capacity (V˙o 2 max/mixed venous Po 2) was lowest in group 1 and comparable in groups 2 and 3. We conclude that lowering Hb P50 has opposing effects onT˙o 2 max and O2 extraction ratio, with the relative magnitude of these changes, which varies with Pi O2 , determiningV˙o 2 max. Although the lower O2 extraction ratio of groups 2 vs. 3suggests a decrease in tissue Po 2 diffusion gradient secondary to the low P50, the lower O2extraction ratio of groups 1 vs. 2 suggests additional negative effects of sodium cyanate and/or chronically low Hb P50 on tissue O2 transfer.

scholarly journals Ventilatory response to exercise in subjects breathing CO2 or HeO2

1997 ◽  
Vol 82 (3) ◽  
pp. 746-754 ◽  
Author(s):  
T. G. Babb
Keyword(s):  
Maximal Exercise ◽  
Respiratory Mechanics ◽  
Ventilatory Threshold ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Normal Lung ◽  
Normal Lung Function ◽  
Older Subjects ◽  
Breathing Room ◽  
Response To Exercise

Babb, T. G. Ventilatory response to exercise in subjects breathing CO2 or HeO2. J. Appl. Physiol. 82(3): 746–754, 1997.—To investigate the effects of mechanical ventilatory limitation on the ventilatory response to exercise, eight older subjects with normal lung function were studied. Each subject performed graded cycle ergometry to exhaustion once while breathing room air; once while breathing 3% CO2-21% O2-balance N2; and once while breathing HeO2 (79% He and 21% O2). Minute ventilation (V˙e) and respiratory mechanics were measured continuously during each 1-min increment in work rate (10 or 20 W). Data were analyzed at rest, at ventilatory threshold (VTh), and at maximal exercise. When the subjects were breathing 3% CO2, there was an increase ( P < 0.001) inV˙e at rest and at VTh but not during maximal exercise. When the subjects were breathing HeO2,V˙e was increased ( P < 0.05) only during maximal exercise (24 ± 11%). The ventilatory response to exercise below VTh was greater only when the subjects were breathing 3% CO2( P < 0.05). Above VTh, the ventilatory response when the subjects were breathing HeO2 was greater than when breathing 3% CO2( P < 0.01). Flow limitation, as percent of tidal volume, during maximal exercise was greater ( P < 0.01) when the subjects were breathing CO2 (22 ± 12%) than when breathing room air (12 ± 9%) or when breathing HeO2 (10 ± 7%) ( n = 7). End-expiratory lung volume during maximal exercise was lower when the subjects were breathing HeO2 than when breathing room air or when breathing CO2( P < 0.01). These data indicate that older subjects have little reserve for accommodating an increase in ventilatory demand and suggest that mechanical ventilatory constraints influence both the magnitude of V˙eduring maximal exercise and the regulation ofV˙e and respiratory mechanics during heavy-to-maximal exercise.

scholarly journals Ventilatory response to exercise of elite soccer players

2014 ◽  
Vol 9 ◽  
Author(s):  
Adriano Di Paco ◽  
Giosuè A. Catapano ◽  
Guido Vagheggini ◽  
Stefano Mazzoleni ◽  
Matteo Levi Micheli ◽  
...  
Keyword(s):  
Maximal Exercise ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Lung Function Test ◽  
Peak Oxygen Uptake ◽  
Forced Expiratory Volume ◽  
Soccer Players ◽  
Ventilatory Parameters ◽  
Response To Exercise

Background: The purpose of this study was to evaluate the role of ventilatory parameters in maximal exercise performance in elite soccer players. Methods: From September 2009 to December 2012, 90 elite soccer players underwent evaluation of lung function test and ergospirometry by means of an incremental symptom-limited treadmill test. Results were analyzed according to i) maximal exercise velocity performed (Hi-M: high-performers, >18.65 km/h; Lo-M: low-performers, <18.65 km/h) and ii) usual role in the team. Results: Hi-M showed higher peak minute ventilation (V_ Epeak: 158.3 ± 19.5 vs 148.0 ± 18.54 L/min, p = 0.0203), and forced expiratory volume at first second (5.28 ± 0.50 vs 4.89 ± 0.52 liters, p < 0.001) than Lo-M, independently of playing role. Moreover, a significant correlation between peak oxygen uptake and V_ E (r = 0.57, p < 0.001) was found. Conclusions: Ventilatory response plays a role in the assessment of exercise capacity in elite soccer players.

Comprehensive Study of Heart Rate Recovery and Altered Ventilatory Response to Exercise in Patients with Obstructive Sleep Apnea

2021 ◽  
Vol 23 (Supplement_D) ◽  
Author(s):  
Laila Abd Elhaleem Banawan ◽  
Rasha Galal Daabis ◽  
Heba Ahmed Eshmawey ◽  
Hend Ramadan Attia Abd Elhaleim
Keyword(s):  
Heart Rate ◽  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Maximal Exercise ◽  
Ventilatory Response ◽  
Heart Rate Recovery ◽  
Cardiopulmonary Exercise Testing ◽  
Obstructive Sleep ◽  
Response To Exercise ◽  
Maximal Exercise Capacity

Abstract Background Obstructive sleep apnea (OSA) is a chronic disorder that results in many cardiovascular disorders including hypertension, arrhythmias and congestive heart failure (CHF). Polysomnography is the gold standard for diagnosis of OSA, even though up to 93% of women and 82% of men with moderate to severe OSA still remain undiagnosed. Cardiopulmonary exercise testing (CPXT) has been conventionally used for evaluation of coronary artery diseases and rehabilitation of cardiac patients. Modern systems allow for the analysis of gas exchange at rest, during exercise, and during recovery and also yield measures of oxygen uptake (V O2), carbon dioxide output (V CO2), and minute ventilation (V E) together with heart rate, blood pressure, electrocardiography findings, and symptoms. This may have clinical utility if added to the available screening tools used to identify OSA. Aim of study To assess altered ventilatory response and heart rate recovery in response to exercise in patients with obstructive sleep apnea and their relation to its severity. Methods and Results Case control study was enrolled including 30 patients with obstructive sleep apnea (OSA) divided according to severity (5 mild, 8 moderate and 17 severe) and 15 control healthy overweight with sedentary lifestyle individuals. The two groups underwent cardiopulmonary exercise testing and different pulmonary and cardiac parameters were calculated. Greater VE, VE/VCO2, VE/VO2 ratios and VE/VCO2 slope were statistically significant regarding the patients group (P &lt; 0.001, F = 69.053, 104.381, 140.806 and 68.010 respectively according to ANOVA test). OSA patients had a reduced maximal exercise capacity expressed as lower VO2 peak, decreased breathing reserve (BR) and VO2 at anaerobic threshold compared to control group (P &lt; 0.001, F = 22.597, 68.773 and 82.90 respectively). Delayed heart rate recovery (HRR) and weaker chronotropic response (CR) in patients with OSA than in controls with negative relationship to severity of OSA were proved (p &lt; 0.001, F = 119.493 and 91.271 respectively). The study revealed elevated maximal systolic BP (max SBP), diastolic BP (max DBP) and recovery SBP in the following 2 minutes after exercise in patients with OSA relative to their healthy controls with positive relationship to the severity of OSA (P &lt; 0.001, F = 37.129, 169.275 and 244.609 respectively). Conclusion Patients with OSA demonstrated exaggerated ventilatory response to exercise and autonomic dysfunction reflected by measurement of heart rate variability and reduced maximal exercise capacity than healthy controls. Abbreviations OSA, CHF, CPXT, VO2, VCO2, VE, VE/VCO2, VE/VO2, VE/VCO2, BR, CR, HRR, max SBP and max DBP.

Ventilation and breathlessness on maximal exercise in patients with interstitial lung disease after local anaesthetic aerosol inhalation

1988 ◽  
Vol 74 (3) ◽  
pp. 275-281 ◽  
Author(s):  
A. J. Winning ◽  
R. D. Hamilton ◽  
A. Guz
Keyword(s):  
Interstitial Lung Disease ◽  
Lung Disease ◽  
Maximal Exercise ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Statistical Significance ◽  
Co2 Production ◽  
Arterial Oxygen ◽  
Cough Reflex ◽  
Response To Exercise

1. The ventilatory response to maximal incremental exercise and the accompanying sensation of breathlessness were studied after the inhalation of 0.9% sodium chloride (saline) and 5% bupivacaine aerosols in six patients with interstitial lung disease. 2. The adequacy of airway anaesthesia induced by bupivacaine aerosol was confirmed by the absence of the cough reflex to 5% citric acid aerosol on completion of exercise. 3. All subjects first performed a trial exercise test to familiarize them with the procedure and to assess the degree of arterial oxygen desaturation on exercise. In subsequent tests, supplementary oxygen was given to maintain the saturation at 95% or above. 4. Airway anaesthesia had no effect on the ability to perform exercise as assessed by maximum workload, CO2 production or heart rate. No significant changes were seen on the pattern of breathing, minute ventilation or endtidal Pco2 on exercise. There was, however, a small but statistically significant increase in ventilation related to CO2 production (VE/Vco2) at the end of exercise. 5. There was a tendency for breathlessness to be increased by airway anaesthesia but this did not reach statistical significance. 6. These results provide no evidence that vagal afferent activity is responsible for the abnormal ventilatory response to exercise in patients with interstitial lung disease. The perception of breathlessness in these patients was not diminished by anaesthesia of the airway.

Vascular adaptations to hypoxia: molecular and cellular mechanisms regulating vascular tone

2007 ◽  
Vol 43 ◽  
pp. 105-120 ◽  
Author(s):  
Michael L. Paffett ◽  
Benjimen R. Walker
Keyword(s):  
Vascular Tone ◽  
Cellular Proliferation ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Hypoxia Inducible Factor ◽  
Systemic Circulation ◽  
Cellular Mechanisms ◽  
Hypoxia Inducible Factor 1 ◽  
Pulmonary Vasoconstriction ◽  
Adaptive Mechanisms ◽  
Adaptive Processes

Several molecular and cellular adaptive mechanisms to hypoxia exist within the vasculature. Many of these processes involve oxygen sensing which is transduced into mediators of vasoconstriction in the pulmonary circulation and vasodilation in the systemic circulation. A variety of oxygen-responsive pathways, such as HIF (hypoxia-inducible factor)-1 and HOs (haem oxygenases), contribute to the overall adaptive process during hypoxia and are currently an area of intense research. Generation of ROS (reactive oxygen species) may also differentially regulate vascular tone in these circulations. Potential candidates underlying the divergent responses between the systemic and pulmonary circulations may include Nox (NADPH oxidase)-derived ROS and mitochondrial-derived ROS. In addition to alterations in ROS production governing vascular tone in the hypoxic setting, other vascular adaptations are likely to be involved. HPV (hypoxic pulmonary vasoconstriction) and CH (chronic hypoxia)-induced alterations in cellular proliferation, ionic conductances and changes in the contractile apparatus sensitivity to calcium, all occur as adaptive processes within the vasculature.

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