Search Results
Results 551 - 600 of 827
< 7 8 9 10 11 12 13 14 15 16 17 >
Gustin P - - 1988
Eleven double-muscled calves of the Belgian White and Blue breed and eleven Friesian calves have been investigated at rest, during exercise on a treadmill (11% incline; speed 1.3 m.sec-1) and 10 and 30 minutes after the end of this exercise. Blood gases and acid-base status were determined in mixed venous ...
Ishida K - - 1988
In the untrained subjects, inhalation of 4.5-6.0% CO2 prior to maximal treadmill exercise does not affect physical performance and maximum oxygen uptake, while blood lactate levels during recovery have a tendency to greater decrease in CO2 breathing than that in the room-air breathing. It was suggested that CO2 inhalation immediately ...
Brice A G - - 1988
We studied the role of central command mediation of exercise hyperpnea by comparing the ventilatory and arterial CO2 partial pressure (PaCO2) responses to voluntary (ExV) and electrically induced (ExE) muscle contractions in normal, awake human subjects. We hypothesized that if central command signals are critical to a normal ventilatory response, ...
Brice A G - - 1988
We studied the role of spinal afferent pathways in the hyperpnea of electrically induced muscle contractions (ExE). The ventilatory (VE) and arterial CO2 partial pressure (PaCO2) responses were measured at rest and during two levels of ExE in awake human paraplegic subjects with clinically complete lesions of the spinal cord ...
Norfleet W T - - 1987
Previous studies have shown that, upon breaking a maximal breath-hold (BH), reinhalation of the expired gas allows an additional period of breath-holding. This indicates that mere ventilatory movements can diminish the urge to breathe. We sought to determine if vigorous ventilations, performed immediately prior to a maximal BH and in ...
Murphy K - - 1987
1. Continuous recordings of arterial pH, ventilation, airway CO2 and heart rate were made during rest and during 3-4 min periods of rhythmic leg exercise in four renal patients with arteriovenous shunts. 2. The patients were anaemic (haemoglobin 6.5-9.0 g/dl) but had a normal ventilatory response to exercise as judged ...
Provine R R - - 1987
Using human college-age subjects, the present study tested the commonly cited but previously untested hypothesis that yawning is facilitated by higher than normal levels of CO2 or lower than normal levels of O2 in the blood by comparing the effect on yawning of breathing 100% O2 and gas mixtures with ...
McKelvie R S - - 1987
The ability to determine cardiac output (Q) noninvasively during a nonsteady state (NSS) incremental exercise test was assessed. Seven healthy subjects performed two maximal incremental cycle ergometer exercise tests (100 kpm/min increments every minute), and also steady state exercise (SS) at 25, 50, and 75 percent of their maximum power ...
Kuna S T - - 1987
The effect of hypercapnia on the suppression of efferent hypoglossal and recurrent laryngeal nerve activity by phasic volume feedback was studied in decerebrate paralyzed intubated cats ventilated with a phrenic-driven servo-respirator. The gain of the respirator was altered for single inspirations, and the resulting changes in neural activities were quantified ...
Shirahata M - - 1987
Effects of oligomycin on carotid chemoreceptor responses to O2 and CO2 were investigated using an in situ perfusion technique. Cats were anesthetized, paralyzed, and artificially ventilated. To avoid a possible reaction between an oligomycin-ethanol mixture and blood, we administered oligomycin to the carotid body via cell- and protein-free perfusate. Except ...
Steffensen J F - - 1987
1. Immediately following burst swimming, the oxygen consumption of rainbow trout increased by 71%, carbon dioxide excretion by 104% and the respiratory exchange ratio by 17%. 80 min after burst swimming all of these parameters had returned to levels which were not significantly different from control values. 2. Infusion of ...
Jacobi M S - - 1987
1. Rapid steady-state CO2 responses were determined in six normal subjects at rest and five subjects at four different work loads up to 125 W, by injecting pure CO2 at constant flow into a small mixing chamber in the inspiratory limb of a breathing circuit. 2. The time course of ...
Haffor A S - - 1987
The purpose of this study was to compare CO2 storage capacity of endurance and sprint-trained athletes during steady state exercise. Ten subjects, five sprinters and five distance runners, performed a submaximal treadmill exercise at two different work rates, 45% and 65% of VO2max. CO2 storage capacity was determined by measuring ...
Van Lunteren E - - 1987
To examine the effects of focally cooling three areas (rostral, intermediate, and caudal) of the ventral medullary surface (VMS) on respiratory oscillations in cervical sympathetic and phrenic nerve activity, 12 cats were anesthetized, vagotomized, paralyzed, and artificially ventilated with 7% CO2 in O2. Cooling the intermediate area from 37 to ...
Poon C S - - 1987
A model of the respiratory control system incorporating both chemical and respiratory neuromechanical feedbacks is proposed to describe the steady-state ventilatory responses to CO2 inhalation and exercise. It is postulated that ventilatory output (VE) is set by the respiratory center to minimize a net operating cost representing the conflicting challenges ...
Bonekat H W - - 1987
To further study the relationship between ventilatory response (VR) and exercise performance, and to investigate to what extent progesterone is responsible for ventilatory changes in the luteal phase of the menstrual cycle, we administered medroxyprogesterone acetate (MPA) to 10 normal males (20 mg three times a day for 5 doses) ...
Dombovy M L - - 1987
We investigated the effects of the luteal phase of the menstrual cycle, as compared with the follicular phase, on ventilatory response (VR) and exercise performance in eight normally menstruating, non-athletic women. Subjects were studied near the predicted mid-point of each phase which was later documented by serum progesterone level. Resting ...
Sassoon C S - - 1987
We investigated the mechanism of hyperoxic-induced hypercapnia in 17 stable patients with moderate to severe chronic obstructive pulmonary disease (mean FEV1 = 0.95 L and FVC = 2.43 L). Ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia were measured with standard rebreathing techniques. In a randomized, single-blind ...
Hinderliter A L - - 1987
Two noninvasive methods of cardiac index (Q) determination, pulsed Doppler echocardiography (QDop), and CO2 rebreathing (QCO2) were compared to dye dilution in eight normal volunteers. Measurements of Q were made by dye dilution (QDD) and the two noninvasive techniques under the following conditions: supine rest, after inflation of cuffs around ...
Cha E J - - 1987
Lung volume changes during CO2 inhalation and exercise were compared in seven human subjects. Expiratory reserve volume (ERV) normalized by vital capacity (VC) was used as an index of end-expiratory lung volume (EELV). Work loads tried were 30, 60, and 90 W and inspired CO2 concentrations were 3.5 and 5.0%. ...
Scardella A T - - 1987
Hypercapnia in patients with pulmonary disease is believed to result from an interaction between mechanical lung impairment and intrinsic chemical respiratory drive. We tested this hypothesis in this study by examining the ventilatory (delta VE/delta PCO2) and occlusion pressure (delta P100/delta PCO2) responses to CO2 in 12 obese patients with ...
Weinberger S E - - 1987
To investigate whether endogenous opioid peptides mediate time-dependent changes in ventilatory control during prolonged hypoxia, we studied four adult goats at rest during 14 days at simulated high altitude in a hypobaric chamber (PB approximately 450 Torr). Arterial PCO2 fell during the first several hours of hypoxia, remained stable over ...
Henneberg S - - 1987
Because of large stores of CO2 in different body tissues, metabolic change cannot be detected by measuring gas exchange until the CO2 stores have adapted to the new situation. Similarly, changes in the CO2 stores not due to metabolic alterations, may lead to error in gas exchange measurements. We studied ...
Shibuya I - - 1987
Quantitative relations between O2 uptake (Vo2), arterial-venous O2 content difference [a-v)CO2), and contact time (tc) were measured at rest and during exercise in 7 normal subjects, using a rebreathing technique. By injecting a known amount of pure O2 into a rebreathing circuit, the VO2 was measured from the time interval ...
Schuster K D - - 1987
A major difficulty in the measurement of carbon dioxide diffusing capacity is the development of significant CO2 back pressure within the capillary. The use of oxygen-labeled CO2 limits this back pressure due to rapid dilution of the label into the water pool by isotopic exchange. We demonstrated the use of ...
Fawcett S - - 1987
Eight patients receiving maintenance haemodialysis were studied under six different dialysis protocols, comprising Cuprophan and polyacrylonitrile (PAN 15) membranes, each used with dialysate containing 40 mmol/l acetate, 30 mmol/l acetate or bicarbonate (35 mmol/l), all other constituents being identical. Blood and expired gas determinations as well as transfer factor (DLCO) ...
Yano T - - 1987
The purpose of this study was to investigate the differences in kinetics of CO2 output (VCO2) during incremental exercise in sprinters (S), middle (MD), and long distance runners (LD). In the steady state exercise, the VCO2 was linearly related to the O2 uptake (VO2). In the incremental exercise below anaerobic ...
Gigliotti F - - 1987
In order to evaluate the separate effects of aminophylline on the neural and muscular components of the respiratory control system, assessed by electromyographic activity of the diaphragm (EMGd) and mouth occlusion pressure (P0.1), respectively, 6 normal subjects and 14 patients with mild or moderate chronic airflow obstruction (8 asthmatics and ...
D'Urzo A D - - 1987
Eight healthy volunteers performed gradational tests to exhaustion on a mechanically braked cycle ergometer, with and without the addition of an inspiratory resistive load. Mean slopes for linear ventilatory responses during loaded and unloaded exercise [change in minute ventilation per change in CO2 output (delta VE/delta VCO2)] measured below the ...
Oliven A - - 1987
The effect of methacholine-induced bronchoconstriction on the electrical activity of respiratory muscles during expiration was studied in 12 anesthetized spontaneously breathing dogs. Before and after aerosols of methacholine, diaphragm, parasternal intercostal, internal intercostal, and external oblique electromyograms were recorded during 100% O2 breathing and CO2 rebreathing. While breathing 100% O2, ...
Powers S K - - 1987
The purpose of these experiments was to examine the temporal pattern of arterial carbon dioxide tension (PaCO2) to assess the relationship between alveolar ventilation (VA) and CO2 return to the lung at the onset and offset of submaximal treadmill exercise. Five healthy ponies exercised for 8 min at two work ...
Boetger C L - - 1986
The effect of exogenous dopamine on the development of exercise hyperpnea was studied. Using a bicycle ergometer, five subjects performed repetitive square-wave work-load testing from unloaded pedaling to 80% of each subject's estimated anaerobic threshold. The breath-by-breath ventilation (VE), CO2 production (VCO2), and O2 consumption (VO2) responses were analyzed by ...
Malvin G M - - 1986
The effects of lung O2 and CO2 content and volume on cutaneous gas exchange and perfusion were investigated in the frog, Rana pipiens. (Ha)-anesthetized frogs were equilibrated with 9.5% Freon-22 (Fr, chlorodifluoromethane) and 1.1% Ha. Cutaneous elimination of Fr, Ha, and CO2 into a small sample chamber on the abdomen ...
Brackenbury J H - - 1986
Clavicular air sac pressure, arterial blood gases and pH, and rectal temperature were measured in treadmill-exercised cockerels breathing air, 10% O2 in N2 or a mixture of 10% O2/3% CO2 in N2. Air sac pressures were used to estimate changes in the rate and the relative depth of breathing. In ...
Gardner W N - - 1986
The respiratory responses of 17 patients with chronic hyperventilation but without demonstrable organic disease (group H) to various manoeuvres were compared with those of 21 healthy controls (group C). The responses were tested according to a 60 min protocol in which periods of rest were replaced by exercise, voluntary hyperventilation ...
Nattie E E - - 1986
Intravenous infusion in conscious rabbits of Hacetate decreases both arterial CO2 partial pressure PaCO2 and cerebrospinal fluid (CSF) HCO3- more than observed with HCl or HNO3 infusion. These acids did not affect CSF HCO3- in isocapnic conditions, and this study asks whether Hacetate infusion will do so. Arterial, central venous, ...
Gautier H - - 1986
In conscious intact cats, oxygen breathing for up to 1 h does not modify ventilation, and the ventilatory response to CO2 in hyperoxia is not consistently decreased. However, oxygen breathing induces sustained hyperventilation in conscious cats after carotid body denervation. In anesthetized cats, oxygen breathing provokes a hypoventilation which is ...
Huszczuk A - - 1986
We determined the role of blood flow-induced changes in CO2 load to the lungs on ventilatory control, at rest and in the steady-state of electrically induced exercise, in the anesthetized dog. A portion of the vena caval blood was diverted to the descending aorta following "arterialization" through an extracorporeal gas ...
Clifford P S - - 1986
Previous investigators have assumed that during exercise there is a tight coupling of ventilation with CO2 delivery to the lungs such that arterial blood remains isocapnic. We measured arterial blood gases in a group of 10 beagle dogs in which arterial blood sampling could be accomplished via exteriorized carotid artery ...
Forster H V - - 1986
Carotid body-denervated (CBD) ponies have a less than normal increase in arterial PCO2 (PaCO2) when inspired CO2 (PICO2) is increased, even when pulmonary ventilation (VE) and breathing frequency (f) are normal. We studied six tracheostomized ponies to determine whether this change 1) might be due to increased alveolar ventilation (VA) ...
Tallman R D RD - - 1986
The ventilatory response to a reduction in mixed venous PCO2 has been reported to be a decrease in breathing even to the point of apnea with no change in arterial CO2 partial pressure (PaCO2), whereas a recent report in exercising dogs found a small but significant drop in PaCO2 (F. ...
Mussell M J - - 1986
Hyperventilation of cold dry air initiates bronchospasm in most if not all asthmatics. The hyperventilation challenge is a useful means of studying asthma and the evaluation of anti-asthma drugs and treatments; two key elements of such a challenge are the means of achieving a target minute-ventilation and the maintainance of ...
Katz-Salamon M - - 1986
Influence of increased CO2 drive for ventilation on the ability to judge lung volume was studied in seven healthy subjects. The psychophysical relationships between the objective and subjective magnitudes of lung volume were tested during air breathing and at two levels of hypercapnia (breathing 4% and 6% CO2 in oxygen). ...
Cummin A R - - 1986
Rapid steady-state CO2 responses were determined in five normal adults at rest and at up to six levels of exercise by injecting pure CO2 at a constant flow into the inspiratory limb of a breathing circuit. Ventilation (V) was measured with a dry gas meter and PCO2 at the mouth ...
Askanazi J - - 1986
The ventilatory responses to catecholamine infusions have been well studied. Increases in plasma levels of cortisol and glucagon during stress may exert a synergistic effect with epinephrine. We examined the effect of epinephrine and a combined hormone infusion in four normal postabsorptive subjects. On three separate occasions each subject was ...
Cooper K R - - 1986
To determine whether hypercapneic ventilatory response (HCVR) is affected by repeated testing, the HCVR of 22 healthy subjects was determined daily for 4 consecutive days. The slope (S) of the HCVR increased to a maximum on Day 3, which was 14% greater than S on Day 1 (p less than ...
Beaver W L - - 1986
Excess CO2 is generated when lactate is increased during exercise because its [H+] is buffered primarily by HCO-3 (22 ml for each meq of lactic acid). We developed a method to detect the anaerobic threshold (AT), using computerized regression analysis of the slopes of the CO2 uptake (VCO2) vs. O2 ...
Weissman C - - 1986
Nutritional intake plays an important role in determining metabolic and respiratory demands during both rest and exercise. This study examines the effects in normal subjects of 4 days of semistarvation with 440 kcal/day of intravenously infused dextrose followed by the infusion of 480 kcal/day of amino acids for 48 h ...
Nickerson B G - - 1986
The continuous, noninvasive estimation of arterial carbon dioxide tension (PaCO2) by heated skin surface electrodes has recently become available for pediatric patients. Skin surface (PsCO2) electrodes can enhance the safety of procedures such as intubation, bronchoscopy, ventilator changes, sleep studies, or measurement of the ventilatory response to CO2 or hypoxia. ...
Escourrou P - - 1986
To verify if the improvement in gas exchange observed at rest with almitrine in patients with chronic air-flow obstruction is maintained at exercise, we studied 10 patients on a randomized, crossover, double-blind exercise protocol. After assessment of steady state of their disease, patients with FEV 1 less than 1.5 L.s-1 ...
< 7 8 9 10 11 12 13 14 15 16 17 >