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Biomedical subjects

G G Isaev

Publications and source records attributed to G G Isaev.

At least 37 records · Page 2Linked to original sources
PubMed1981

[Importance of chemoreceptor stimuli to the speed of switching the respiratory response to exertion on and off].

The magnitude of the exercise respiratory response and its switch on and switch off rates were studied in 12 normal men breathing different gas mixtures. It was shown that hypercapnic stimulus reinforced and accelerated the respiratory response to exercise. Hypoxic stimulus mostly resulted in the increased though transient changes in the ventilatory rate at the start and at the end of exercise. This effect seems likely to be mediated by the fast-responding arterial chemoreceptors.

Adult↗
PubMed1979

[Relationship between hypercapnic and hypoxic stimuli of respiration during muscular activity].

Pulmonary ventilation (V) and alveolar gas composition (PACO2, PAO2) were studied in 12 healthy men who performed gradual muscular work under conditions of controlled hypercapnia, hypoxia, hyperoxia or their combinations. The respiratory response was estimated by absolute values of ventilation at the given PACO2 value and by its rise by 1 mm Hg of increased PACO2 (delta V/delta PACO2) under rest and under transitional and steady-state exercise. The exercise on-switch was accompanied by displacement to the top and an increased slope of the response curve (delta V/delta PACO2) not related to the work load. These changes suggest multiplicative interaction of the neurogenic and hypercapnic drives in the load switch-on. During steady-state exercise an important role of the hypoxic drive was revealed: hypoxemia induced a shift of the delta V/delta PACO2 response curve to a higher level, especially with the great work load. Thus the positive interaction between the hypercapnic and hypoxic respiratory drive augments with muscular exercise.

Adult↗
PubMed1978

[Criteria for quantitative assessment of respiratory system reactions].

In anesthetized cats and in healthy humans, lung ventilation, activity of diaphragmal motoneurons and intercostal muscles, shift of the intrathoracic pressure, inspiratory occlusional pressure, and maximal rate of the initial increase in inspiratory pressure, were studied. Depending on conditions of the respiratory system functioning, any one from among the above parameters can reflect the efferent output of the respiratory center. Each of them, however, has limitations of its own.

Animals↗
PubMed1976

[Mechanism of the fast neurogenic component of the respiratory response to muscular work].

Dynamics of pulmonary ventilation, electric activity of the intercostal muscles and of the alveolar gas composition was studied in 12 healthy men during dosaged muscular work; these men were given different gas mixtures to breathe. The respiratory response at the initial period of work in inhalation of the hypoxic-hypercapnic gas mixture was greater than that in persons who breathed room air. This response practically disappeared after oxygen hyperventilation. Apparently the rapid component of the ventilation response to the muscular work was largely due to increased sensitivity of the respiratory centre to the chemoreceptive drive.

Adult↗
PubMedDate not supplied

[Central and peripheral mechanisms of difficult breathing in man].

The review is dedicated of phenomenology of the difficult breathing and analysis of the peripheral and central mechanisms of it. Analysis based on model investigations with resistive loads in awake or sleeping healthy humans, including results of experiments in the anesthetized animals. The recent data having principle importance in estimation of the central mechanisms of the control breathing are included too in the review. It concerned to the contemporary visualization of central neuronal activity on the awake person during dyspnoea. It became possible due to application of the unique precision equipment--functional magnetic--resonance and positron--emission tomography.

Animals↗
PubMedDate not supplied

[Physical performance and function of the cardiorespiratory system in additional respiratory resistance].

This paper presents results of examining respiration and circulation parameters of healthy volunteers pedalling a bicycle ergometer at different degrees of inspiratory-expiratory resistance. In this situation the performance-limiting factor is an increased load on respiratory muscles. An additional signal of performance problems is respiratory discomfort. The paper gives a formula for predicting maximally allowable workloads in response to increased respiration resistance.

Adaptation, Physiological↗
PubMedDate not supplied

[Effect of increased respiratory resistance on human work capacity].

Respiratory responses to external resistive resistance are discussed, having in view data in the literature and experimental results obtained by the present authors. The adverse changes induced by this factor during muscle work are described with special emphasis on performance deterioration. Some considerations are presented which are related to the physiological implications of the maximal allowable values of respiratory resistance produced by the breathing system upon workloads of various intensity and duration.

Airway Resistance↗
PubMedDate not supplied

[Effect of oxygen inhalation on the respiration function during exercise under conditions of added resistance to respiration].

Experiments were performed to investigate the effect of added resistance to inspiratory, expiratory and inspiratory-expiratory respiration on lung ventilation and pACO2 during exercise when breathing air or oxygen. Increase of resistance to respiration, particularly inspiratory-expiratory; reduced the work-induced growth of ventilation which caused pACO2 to increase. Oxygen inhalation aggravated those shifts significantly. The adverse effect of hyperoxia on the respiration function when exercise was combined with added resistance to respiration seems to be associated with inhibition of the respiration center produced by the lack of hyperoxid stimulation.

Adult↗
PubMedDate not supplied

[Evaluation of the effect of excess intrapulmonary pressure on human respiratory function].

The parameters characterizing lung ventilation and electrical activity of expiratory muscles were investigated in six healthy young men exposed to the positive intrapulmonary pressure 20, 30 or 40 mm Hg. Gas mixtures with a varying oxygen content were used. The effect of two compensatory devices that applied different counterpressures to the body surface was evaluated. It was found that the parameter that can best characterize the respiratory function in the case of a positive intrapulmonary pressure is electrical activity of expiratory muscles. The hypoxic effect makes no important contribution to the change of respiratory parameters during short-term exposures to the positive intrapulmonary pressure 20, 30 or 40 mm Hg. The different methods of applying compensation do not influence changes in the above respiratory parameters.

Air Pressure↗