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PubMed2006

Electron paramagnetic resonance oximetry as a quantitative method to measure cellular respiration: a consideration of oxygen diffusion interference.

Electron paramagnetic resonance (EPR) oximetry is being widely used to measure the oxygen consumption of cells, mitochondria, and submitochondrial particles. However, further improvement of this technique, in terms of data analysis, is required to use it as a quantitative tool. Here, we present a new approach for quantitative analysis of cellular respiration using EPR oximetry. The course of oxygen consumption by cells in suspension has been observed to have three distinct zones: pO(2)-independent respiration at higher pO(2) ranges, pO(2)-dependent respiration at low pO(2) ranges, and a static equilibrium with no change in pO(2) at very low pO(2) values. The approach here enables one to comprehensively analyze all of the three zones together-where the progression of O(2) diffusion zones around each cell, their overlap within time, and their potential impact on the measured pO(2) data are considered. The obtained results agree with previously established methods such as high-resolution respirometry measurements. Additionally, it is also demonstrated how the diffusion limitations can depend on cell density and consumption rate. In conclusion, the new approach establishes a more accurate and meaningful model to evaluate the EPR oximetry data on cellular respiration to quantify related parameters using EPR oximetry.

Animals↗
PubMed2000

Effects of slow tempo exercise on respiration, heart rate, and mood state.

The purpose of this study was to investigate psychophysiologic responses to slow movement tempo exercise in three experiments. Exps. 1 and 2 were designed to compare slow with preferred movement tempos chosen freely by the subjects. The task movements in Exp. 1 were repetitive Arm Swinging, Stepping, and Body Swaying, performed by 14 female undergraduate students, while in Exp. 2, Body Swaying and Arm Winding were performed by 10 female undergraduate students and 13 boys and girls junior high school students. Respiration, heart rate, and scores on the State-Trait Anxiety Inventory were measured. Analysis showed respiration rates were lower during slow tempo conditions than preferred conditions. Exp. 3 was designed to compare very slow with slow movement tempos, using a Tai Chi-type of movement performed by 6 female undergraduate students. The subjects were required to synchronize the task movement with auditory stimuli, during which respiration and heart rate were measured, and a UWIST Mood-Adjective Checklist was utilized. Under the very slow movement conditions, Energetic Arousal scores were lower than those for the slow movement and the variation of respiration between rest and task conditions corresponded inversely with the Tense Arousal scores. Together, our results suggest that slow tempo exercise does not increase physiological or psychological arousal.

Adolescent↗
PubMedDate not supplied

Spontaneous nasal oscillations in dog. A mucosal expression of the respiration-related activities of cervical sympathetic nerve.

We studied the respiratory oscillations of the nasal mucosa in dogs. Even after temporarily stopping the respirator, intranasal balloon pressure showed respiration-related oscillations (spontaneous nasal oscillations). These spontaneous oscillations were recorded in all 21 dogs. Spontaneous nasal oscillations were not abolished even after thoracotomy, vagotomy and vidian neurectomy. Only cervical sympathectomy could to a large extent abolish the spontaneous nasal oscillations. Furthermore, the spontaneous nasal oscillations were found to be synchronized with the respiration-related fluctuations of cervical sympathetic nerve activities. Rhythms of the spontaneous nasal oscillations were not dependent on the rates of artificial ventilation, but were closely related to the rates of spontaneous respiration before administering the muscle relaxant. On some occasions, we recognized remarkable differences in the height of waves of the spontaneous nasal oscillations between the sides of the body. On eight occasions in 5 dogs, reciprocal changes of the dominant side of bilateral spontaneous nasal oscillations were noted which might be an expression of the nasal cycle.

Animals↗
PubMed1996

Influence of vestibular organ stimulation on stomach movement and respiration.

Some previous investigators have reported controversial results in the stomach movement in response to labyrinthine stimulation (1). The purpose of the present study was to investigate the influence of vestibular stimulation on the stomach movement and respiration in anesthetized cats, and to investigate the differences between increased and decreased responses of the stomach movement. This study used an electrophysiological technique: a bipolar stainless-steel stimulating electrode with a tip diameter of 20 microns introduced chronically into the anterior and/or lateral semicircular canal (2). The intragastric pressure was recorded by using a balloon-transducer system. Respiration was recorded by measurement of the thorax. When the peripheral labyrinth was stimulated, we found conflicting results in that the pressure in the stomach increased several times and sometimes decreased. Respiration usually became irregular or intensified. It seems that forced respiration may be involved in vestibular vomiting but we were unable to induce vomiting.

Animals↗
PubMed2000

[Effect of sodium alpha-ketoglutarate injected after x-ray treatment on the respiration and oxidative phosphorylation of hepatic mitochondria].

It have been found that total X-ray treatment (everyday expose to 1 Roentgen up to achievement of total doses 10, 20 30 Roentgen) inhibits the rate of ADP-stimulated respiration of rat liver mitochondria, decreases its efficiency and makes phosphorylation less couple to respiration. All this effects are present from the first period after treatment till the end of treatment. Intraperitoneal alpha-ketoglutarate injections during treatment decreases the inhibition of respiration and oxidative phosphorylation, increases the efficiency of respiration during the period from 1-st injected till the end of experiment.

Adenosine Diphosphate↗
PubMed2001

[Evaluation of brain ischemia by mitochondrial respiration: experimental model].

Brain ischemia occurs in several diseases. One of the critical factors for recovery of patients is the duration of the ischemic process. Brain activity depends on the energetic supply, it suggests that the study of mitochondrial function can be useful for evaluation of neuronal damage. The purpose of the present research was to study the mitochondrial respiration by occlusion of the left middle cerebral artery by intraluminal suture technique. Adults Wistar rats were subdivided in 4 groups: control, 15, 30 and 60 minutes of occlusion. Results showed that there was no significant difference between the group of 15 minutes and the control group. The group of 30 minutes had significant decrease of state III of mitochondrial respiration compared with control group. The group of 60 minutes had significant decrease in state III and IV of mitochondrial respiration compared with control group. Mitochondrial respiration allowed an early and effective evaluation of focal ischemic process of the rat brain.

Animals↗
PubMedDate not supplied

[Change in intensity of respiration in development of some invertebrates].

We studied the dynamic of respiration intensity during ontogenesis of flat worms (Dugesia tigrina), molluscs (Anodonta piscinalis and Viviparus viviparus, and insects (Leptinotarsa decemlineata). In planarians that reproduce vegetatively, the intensity of respiration increases just after fission and decreases at the subsequent phases of growth. In A. piscinalis, this index of metabolism increases during embryonic and early larval development and decreases at the later developmental stages. In V. viviparus, which develops in the female genital tract, the intensity of respiration remains unchanged during embryogenesis and decreases during late embryogenesis and subsequent phases of growth. In L. decemlineata, the intensity of respiration increases during embryonic and early larval development and then decreases to undergo cyclic changes times to molts. This index markedly decreases in the pupae, increases in the beginning of imaginal period, and then again decreases.

Animals↗
PubMed2003

[Respiration-gated radiotherapy: current techniques and potential benefits].

Respiration-gated radiotherapy offers a significant potential for improvement in the irradiation of tumor sites affected by respiratory motion such as lung, breast and liver tumors. An increased conformality of irradiation fields leading to decreased complications rates of organs at risk (lung, heart...) is expected. Respiratory gating is in line with the need for improved precision required by radiotherapy techniques such as 3D conformal radiotherapy or intensity modulated radiotherapy. Reduction of respiratory motion can be achieved by using either breath hold techniques or respiration synchronized gating techniques. Breathhold techniques can be achieved with active, in which airflow of the patient is temporarily blocked by a valve, or passive techniques, in which the patient voluntarily breath-hold. Synchronized gating techniques use external devices to predict the phase of the respiration cycle while the patient breaths freely. These techniques presently investigated in several medical centers worldwide. Although promising, the first results obtained in lung and liver cancer patients require confirmation. Physical, technical and physiological questions still remain to be answered. This paper describes the most frequently used gated techniques and the main published clinical reports on the use of respiration-gated radiotherapy in order to evaluate the impact of these techniques.

Breast Neoplasms↗
PubMed2004

Modulation of osmotic stress effects on photosynthesis and respiration by temperature in mesophyll protoplast of pea.

Exposure of mesophyll protoplast of pea to osmotic stress decreases the rate of photosynthesis while stimulating marginally the respiratory rate of mesophyll protoplasts. The interaction of osmotic and temperature stress during the modulation of photosynthetic and respiratory rates of pea (Pisum sativum var Azad P1) mesophyll protoplasts was investigated. The protoplasts were exposed to either iso-osmotic (0.4 M) or hyper-osmotic (1.0 M) concentration of sorbitol at 15 degrees and 25 degrees C. The rates of photosynthesis and respiration were studied. At optimum temperature of 25 degrees C, there was a decrease in photosynthesis (< 10%) at hyper-osmoticum (osmotic effect), whereas respiration increased marginally (by about 15%). Low temperature (15 degrees C) aggravated the sensitivity of both respiration and photosynthesis to osmotic stress. At 15 degrees C, the decrease in photosynthesis due to osmotic stress was > 35%, while the respiratory rate was stimulated by 30%. The relative proportion of cytochrome pathway decreased by about 50% at both 15 degrees C and 25 degrees C while that of alternative pathway increased, more so, at 15 degrees C, when the mesophyll protoplasts were subjected to hyper-osmoticum stress. The titration experiments showed that extent of engagement of alternative pathway was higher, the slope value was slightly higher for 15 degrees C compared to 25 degrees C. Low temperature modulates the effect of hyper-osmoticum stress on photosynthesis and respiration, and results in increased participation of alternative pathway.

Cell Respiration↗
PubMed2006

[Effects of pentobarbital sodium on rhythmical respiration of neonatal rat medullary preparations].

OBJECTIVE: To study the effects of pentobarbital sodium in generation and modulation of rhythmical respiration in neonatal rats. METHODS: The effects of pentobarbital sodium were examined on hypoglossal nerve (XII) rootlets and inspiratory neurons in the medullary preparations including the medial region of the nucleus retrofacialis, pre-Bötzinger complex and the dorsal respiratory group of neonatal rats aged 0-3 days. The electrical activity of XII nerve rootlets and inspiratory neurons were recorded. Different doses of pentobarbital sodium (20, 40, 60, 80 micromol/L) were added into modified Krebs solution to observe changes in the discharge activity of XII nerve and inspiratory neurons. Bicuculline was used to further investigate the mechanisms that pentobarbital sodium suppresses respiration. RESULTS: The discharge activity inhibition of XII nerve was increased as pentobarbital sodium doses increased from 20 to 60 micromol/L, but no significant difference was observed between the doses of 60 and 80 micromol/L. Bicuculline can partly restore the rhythmical respiration discharge activity. CONCLUSION: Pentobarbital sodium can suppress respiration partly via GABAA receptors.

Adjuvants, Anesthesia↗
PubMed1991

[Effects of intracarotid injection of adenosine on respiration blood pressure and renal sympathetic nerve activity].

Changes of mean arterial pressure (MAP), heart rate (HR), respiration and renal sympathetic nerve activity (RSNA) induced by close-arterial administration of adenosine to carotid body (CB) were observed in 33 anesthetized rabbits. The results were as follows: (1) In response to intracarotid injections of adenosine, MAP decreased in a dose-dependent manner, while the frequency of respiration increases with little change in depth. Following carotid sinus denervation, intracarotid injection of adenosine still resulted in a decrease of MAP but with no changes in respiration. (2) By adding adenosine to perfusate of the isolated carotid sinus, both MAP and HR decreased, but these effects could be abolished by inactivation of carotid body. (3) MAP decreased and RSNA enhanced during perfusing adenosine into carotid sinus. These effects could be abolished by the section of sinus nerve or inactivation of CB. From the results obtained, it is considered that adenosine is capable of activating CB, decreasing MAP and heart rate but with a concomitant increases in respiration and RSNA.

Adenosine↗
PubMed1990

Effect of exercise level on ventilatory adaptation to respirator use.

The effect of exercise on the adaptation to an air-purifying respirator type load (dead space + inspiratory resistance) was studied in a group of 13 volunteers with a rapidly incremental exercise protocol. The difference between loaded and unloaded breathing at each exercise level was determined for each subject for a series of parameters describing the ventilatory work to overcome the respirator load pattern of breathing and metabolic work. Linear regression and t tests determined the average effect of the respirator load and the extent to which this effect was affected by the level of exercise. The inspiratory time and duty cycle were increased by the load, and exercise did not significantly affect the magnitude of this adaptation. High exercise did, however, increase the magnitude of the effect of the respiratory load on ventilatory work. These findings suggest that constraints to respiratory pattern adjustment, which may decrease respirator tolerance, occur at high exercise levels.

Adaptation, Physiological↗
PubMed1989

Improving DRGs. Use of procedure codes for assisted respiration to adjust for complexity of illness.

Medicare's diagnosis related groups (DRGs) payment system has been criticized for not making adequate allowances for severity of illness differences within DRGs. The respiratory diseases major diagnostic category (MDC) has been a particular target; therefore, ability of several procedure codes that identify patients with assisted respiration (temporary tracheostomy, endotracheal intubation, and mechanical respiratory assistance) to identify high-cost patients in that MDC was examined. Total charges were used as the dependent variable in a 10% sample of Medicare hospital discharges from 1985. A consistent and strong association was found between the procedures and total charges for both Medicare "outliers" and "nonoutliers." Patients requiring either intubation or mechanical respiratory assistance had average charges two to three times higher, and patients with tracheostomy four to five times higher than charges for patients without assisted respiration. Patients with assisted respiration tended to resemble each other more than they resembled the other patients in their respective DRGs without assisted respiration. These findings provide the basis for recent revisions in Medicare's classification scheme for the respiratory diseases MDC.

Connecticut↗
PubMed1985

[Regulation of respiration during muscular exertion].

A brief critical review of literature shows that many authors still follow a classical theory that the respiration control is performed by feedback (by deviation of PCO2, PO2 and pH in blood). This point of view does not account for the exercise hyperpnea. The present paper contains the various data and considerations which show that respiration during muscular exercise is controlled by a combined self-learning system. The system is based on both disturbance (open-loop) control and feedback control. The signals of disturbance (of central origin and from receptors of exercising muscles) cause the increase of respiration during exercise. The signals of deviations (from peripheral and central chemoreceptors) correct the response of respiratory centre to disturbance signals. The self-learning takes place by the formation of conditioned reflexes that ensures the control of respiration (the stability of gaseous composition of blood during exercise).

Animals↗
PubMed1987

Respiration and airway reflexes after transversal brain stem lesions in cats.

The effect of brain stem transection at different levels of the pons Varolii and the medulla oblongata on respiration and on cough and the aspiration and expiration reflex elicited by mechanical stimulation of the relevant parts of the respiratory tract was studied in experiments on 13 anaesthetized, unparalyzed cats. The results of 142 respiratory reflex elicitation tests showed that: 1. Compared with the control state, transection of the upper and middle part of the pons Varolii and transection at the level of the pontomedullary junction reduced the respiration rate (p less than 0.001), increased the duration of inspiration and expiration (p less than 0.001, transection 10 mm rostrally to the obex) and gave rise to apneustic breathing (8 mm), or to tonic, respiration-modulated activity of the phrenic nerve and diaphragm (6 mm). 2. Successive transection of the pons and the pontomedullary junction region led chiefly to a drop in maximum expiratory pleural pressure values (p less than 0.01-0.001) during cough and the expiration reflex and to a drop in maximum inspiratory pleural pressure values during the aspiration reflex (p less than 0.02-0.001). 3. Transection of the upper part of the medulla oblongata always led to permanent arrest of rhythmic respiration, during which cough and the expiration reflex could not be elicited while the aspiration reflex persisted (though in a weakened form). This state was followed by gasping, during which only a highly elicitable aspiration reflex persisted. 4. It can be assumed from the above findings that the central mechanisms responsible for the development of powerful expiratory efforts in cough and the expiration reflex could be localized in the pons Varolii, while those integrating the aspiration reflex are probably localized mainly in the medulla oblongata.

Animals↗
PubMed1978

Two early Danish respirators designed for prolonged artificial ventilation.

Two Danish respirators are described. The first one was made by August Krogh in 1931 and was based on the principles of the Drinker tank respirator. The original feature was a motor driven by water from an ordinary water tap. It was never widely used, most likely due to practical problems connected with nursing care, etc. The polio epidemic in Copenhagen in 1952 initiated the era of the IPPV-methods and gave rise to the construction of a great number of new respirators. Among the first of these was the Claus Bang respirator. Although it contained many modern features, it proved technically unreliable and was only used for 3-5 years.

Denmark↗
PubMed1987

Aerial respiration facilitates growth in suspension-feeding anuran larvae (Xenopus laevis).

Xenopus laevis tadpoles are midwater suspension-feeders that use buccopharyngeal surfaces for both food capture and aquatic respiration, but also have functioning lungs well before metamorphosis. To examine the effect of aerial respiration on premetamorphic growth and development in this species, tadpoles were raised in normoxic water for from one to three weeks at three different concentrations of food (yeast cells in suspension). At each food concentration the larvae were either allowed or denied access to air. Xenopus larvae reached greater snout-vent lengths, weighed more and developed more rapidly when allowed to breathe air. The difference in growth and development between those tadpoles with and without access to air was proportional to the concentration of particulate matter. In the extreme, tadpoles denied access to air at the highest food concentration all asphyxiated shortly after the start of the experiment. Xenopus tadpoles faced with the functional conflict of using buccopharyngeal surfaces for both feeding and respiration retard ingestion. They do this, however, not by ceasing mucus outflow to their branchial food traps, as has been speculated previously, but rather by capturing food particles in mucus and then expectorating it. Lungs appear to be advantageous to aquatic organisms even in normoxic water in that they allow buccopharyngeal surfaces to be dedicated fully to feeding rather than respiration.

Air↗
PubMed1987

[Effect of respiration on variations of central venous blood temperature].

We examined the course of right ventricular blood temperature before, during and after treadmill exercise in three patients with implanted cardiac pacemakers, and in two healthy volunteers. Temperature measurements were performed with a specially developed 5F electrode with an incorporated thermistor (measurement accuracy: 1/100 degrees C). After electronic amplification, the temperature signals were recorded on a three-channel strip chart recorder, together with ECG and respiration (measured by impedance plethysmography). In one of the volunteers, blood flow in the jugular and femoral veins was recorded by Doppler sonography, before and after exercise. We observed a decrease in central venous blood temperature with inspiration and an increase with expiration before, during and after exercise. The amplitudes of the variations became smaller during exercise, reached a maximum immediately after exercise and returned to their resting values within a few minutes after the end of exercise. We suppose different distributions of venous blood flow in different phases of the respiratory cycle to be the reason for the respiration-induced variations in central venous blood temperature. Under exercise conditions, the influence of respiration on the blood flow in the larger veins is small compared to the influence of an increased cardiac output; at rest, respiration has a more pronounced effect on venous blood flow. The analysis of our blood flow measurements in the femoral and jugular veins supported this assumption.

Adult↗