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Jennings D B - - 1982
Resting awake dogs breathing CO2 lower body temperature and such a change is reported to decrease the ventilatory response to CO2. Therefore, in 6 awake dogs the ventilatory response to CO2, obtained while body temperature was allowed to decrease spontaneously, was compared to the response obtained during warming of their ...
Ward S A - - 1982
The influence of respired gas density on ventilatory control during cycle-ergometer exercise was investigated in six healthy subjects. They underwent constant-load exercise for 10 min both at 50% and 90% of the anaerobic threshold, inhaling air for the first 5 min followed abruptly by 80% helium-20% oxygen (He-O2) for the ...
Cross B A - - 1982
1. The effect of electrically induced ;exercise' on the respiratory oscillation of arterial pH was studied in chloralose-anaesthetized dogs with spinal cord transection at T8/9 (dermatome level T6/7).2. Respiratory oscillations of arterial pH (presumed to be due to oscillations of arterial P(CO2)) were sensed with a fast-responding electrode in one ...
Kotake A N - - 1982
The optimal conditions for performing the caffeine CO2 breath test (CBT) were investigated in smokers and nonsmokers. Caffeine labeled with 13C or 14C in all three (1, 3, and 7) methyl groups or specifically in the 1-, 3-, or 7-methyl groups were orally administered to healthy adults and the expiration ...
Buono M J - - 1982
Acid-base, metabolic, and ventilatory responses to repeated bouts of exercise were examined. Ten male subjects performed two (T1, T2) 5-min work tests, on a cycle ergometer, separated by a 25-min rest. The results indicate the following. 1) T2 appears to have a larger aerobic energy component than T1, due to ...
Cogan M G - - 1982
The mechanism by which proximal volume reabsorption is reduced during hyperchloremic metabolic acidosis was studied using free-flow micropuncture techniques in Munich-Wistar rats. Compared with control hydropenic conditions, absolute rates of proximal total CO2 and water reabsorption rates during NH4Cl-induced metabolic acidosis were diminished: from 557 +/- 35 to 204 +/- ...
Bisgard G E - - 1982
In the present study the ventilatory response to exercise was measured in goats before and after carotid body excision (CBE) (n = 7) or sham operation (n = 1). Nine-minute periods of moderate treadmill walking were carried out under three conditions: 4.8 kph, 0% grade during normoxia and hypoxia (arterial ...
Raffestin B - - 1982
Twenty patients with chronic bronchitis were exercised maximally on a bicycle ergometer. At exhaustion, arterial partial pressure of O2 (Pao2) decreased and that of CO2 (Paco2) increased in 8 patients (Subgroup 1). Arterial PO2 increased and Paco2 did not change in the remaining 12 patients (Subgroup 2). Forced expiratory volume ...
Oren A - - 1982
To determine the influence of altered carotid body drive on exercise ventilatory kinetics, five subjects performed four repetitions of constant-load cycle ergometer exercise during air and O2 breathing under each of the following conditions: 1) metabolic acidosis, (NH4Cl, 0.3 g . kg-1 . day-1); 2) metabolic alkalosis (NaHCO3, 0.7 g ...
Fordyce W E - - 1982
Recently, the rapid increase in ventilation at the onset of exercise has been attributed to reflexes stimulated by the concomitant increase in cardiac output. To evaluate these 'fast-humoral' hypotheses in supine man, the heart rate, ventilation, and end-tidal PCO2 and PO2 were observed during four procedures: the onset of mild ...
Ward D S - - 1982
To define precisely the effects of dopamine on hypoxic ventilatory drive, two sets of experiments were performed in five healthy subjects. End-tidal CO2 was held constant in all experiments. First, a dopamine infusion (3 microgram/kg/min) was started in subjects already rendered hypoxic, causing an average sustained decrease in ventilation to ...
Verbrugghe C - - 1982
Awake, resting miniature pigs trained to breathe through a respiratory mask were studied at neutral ambient temperature first intact, then after bilateral chronic carotid body denervation. Resting pulmonary ventilation (V), tidal volume (VT) and ventilatory period (T), and O2 and CO2 partial pressures in the end-tidal gas (PETO2, PETCO2) were ...
Hayashi F - - 1982
The ventilatory response to CO2 in rats under sodium pentobarbital anesthesia has been measured using the rebreathing technique. The animal rebreathed through a tracheal cannula for a period of 4 min from an apparatus of 200-400 ml capacity, containing 5-6% CO2 in O2. Pco2 in the rebreathing apparatus (PappCO2), instantaneously ...
Graham T E - - 1982
Studies on isolated muscle and resting man have demonstrated that altering CO2 stores influences intracellular lactate production and/or tissue lactate release. In the present project, subjects (N = 6) performed steady-state exercise for 30 min while inspiring 0, 2, 4, or 6% CO2 and 21% O2. They were tested on ...
Casacó-Parada A R - - 1982
The "exercise hyperpnoea" problem was studied in 44 anaesthetized rabbits by increasing the cardiac output by: a) tilting by 12 degrees the hindlimbs up; b) injecting into the right heart 15 ml of dextran; c) normocapnic or d) hypocapnic blood. In all cases there was an increase in minute ventilation, ...
Ohyabu Y - - 1982
Whether or not stimulation of the peripheral chemoreceptors by hypercapnic-hypoxic exposure results in a long-lasting increase in ventilatory activities was studied using the steady state CO2 response test on 12 human subjects. The degree of hypercapnic hypoxia was end-tidal PCO2 (PETCO2) 42.1 +/- 3.0 and PO2 (PETO2) 39.8 +/- 4.7 ...
Manning T J - - 1981
In the routine performance of their jobs, three men consecutively descended into an open drainage pit to recover a fallen grate lid. Each man, in turn, was immediately overcome and died within minutes of his descent. Initial analysis of the pit's air indicated a methane level of 15%. Therefore, it ...
Morrison J B - - 1981
In a study of respiratory function under hyperbaric conditions one diver (TM) was found to have an extremely low ventilatory response to exercise with a postinspiratory pause typical of certain "carbon dioxide retaining divers." The respiratory function of diver TM is compared with that of four other divers having a ...
Phillipson E A - - 1981
We examined the role of metabolic CO2 production in the hyperpnea of muscular exercise by comparing the response of alveolar ventilation to moderate levels of exercise with the response to venous infusion of CO2 at rest. Studies were performed in four awake sheep that were trained to run on a ...
McLellan P A - - 1981
We studied changes in transcutaneous PCO2 in healthy volunteers and patients to establish the accuracy and practicability of a new cutaneous capnometer (HP47201A). In 9 healthy volunteers, as many as 4 experiments each were performed during each laboratory session. After cutaneous electrode stabilization, a gas mixture of CO2 in O2 ...
Andersen P K - - 1981
The effects of varying ventilations (VE) and fresh gas flows (FGF) on end-expiratory CO2 (FECO2) levels were investigated in an experimental model lung, employing the Hafnia modification of the Mapleson A and D anaesthetic systems during CO2-absorption and CO2-wash-out (rebreathing). Identical results were found in both systems: FECO2 was constant ...
Oren A - - 1981
The ventilatory response to exercise was determined in seven normal adults during induced chronic metabolic acidosis, chronic metabolic alkalosis, and a control state. Incremental and constant-load exercise tests were performed in each condition on a cycle ergometer. Ventilation and gas exchange variables were determined breath by breath, and CO2 partial ...
Bennett F M - - 1981
The dynamics of the ventilatory response to moderate exercise on a bicycle ergometer have been studied in humans. The work load was varied between 25 and 100 W as a pseudorandom binary sequence (PRBS) that enabled the impulse responses to be calculated by cross-correlation techniques. The response of all five ...
Rigg J R - - 1981
An i.v. infusion regimen was developed to permit rapid attainment of steady-state blood pethidine concentrations (Cpss). In 10 adult volunteers (12 studies) the relationship of pethidine Cpss to the ventilatory effects of the drug were examined. Mean pethidine Cpss ranged from 170 to 320 ng ml-1, with a median Cpss ...
Grant B J - - 1981
The purpose of this study was to determine the relationship between the respiratory oscillations of CO2 and the ventilatory response to CO2. Cats anaesthetized with chloralose and urethane were given CO2 either by exchange transfusion into the inferior vena cava or by inhalation. Changes of amplitude of the respiratory oscillations ...
Plewes J L - - 1981
Carbonic anhydrase in lung tissue might play a role in speeding the movement of CO2 between blood and alveolus. To test this hypothesis, we measured the transpleural diffusion rate of CO2 and compared it to that of oxygen, argon, and nitrogen, before and after inhibition of carbonic anhydrase activity with ...
Moss I R - - 1981
We have performed the fetal CO2 response test on eight mature lambs in utero and have found that theophylline is a respiratory stimulant over a wide range of PaO2 and pHa. Theophylline produces significant increase in slope of P100, Pmax, and VEq response curves and significant increase in P100, Pmax, ...
Kiwull-Schöne H - - 1981
In anaesthetized rabbits the influence of differential vagal cold blockade on the ventilatory response to inhaled CO2 during hyperoxia was investigated. Following total inactivation, the relationship between ventilation (V) and arterial PCO2 (PaCO2) was shifted to the left and steepened slightly over a range of modest hypercapnia, but was progressively ...
Takano N - - 1981
We attempted to analyze how PACO2 is regulated during progesterone-induced hyperventilation in the luteal phase. A model for the CO2 control loop was constructed, in which the function of the CO2 exchange system was described as PACO2 = 0.863 x VCO2/VA (gain H = dPACO2/dVA) and that of the CO2 ...
Sargeant A J - - 1981
Five male subjects exercised on a cycle ergometer (100 W) for 8 min; circulation to the legs was occluded by cuffs during the first 2 and last 2 min. Ventilation (VE), oxygen intake (VO2), and carbon dioxide output (VCO2) were measured breath by breath. Repeat studies were used to follow ...
Cormier Y F - - 1981
Because exercise increases the slope of phase III of the single-breath nitrogen (SB-N2) test in normal persons, we hypothesized that this increase might be due to increased O2 consumption. During the prolonged expiration implicit in the SB-N2 test, the amount of O2 absorbed is greater than the amount of CO2 ...
Jussila E J - - 1981
Oxygen and carbon dioxide tensions were measured pre- and postoperatively in the gastrocnemius muscles of 6 patients undergoing an aorto- femoral reconstruction due to occlusive arterial disease. Four volunteer patients showing no signs of arterial ischaemia formed the control group. Continuous recordings of tissue gas tensions were carried out by ...
Hulsbosch M A - - 1981
Investigations in our laboratory have shown an increased slope of the ventilatory response curve to CO2 (CO2 sensitivity) during positive and negative exercise as compared with the resting condition. CO2 sensitivity during positive and negative exercise did not differ in spite of differences in metabolism (VO2, VCO2) and type of ...
Itabisashi T - - 1981
Phenomena associated with a deformation of short-time occurrence and noticed on concentration curves of tidal O2 and CO2 were examined in adult hens sitting quietly in a cage or suspended in prone position. During the episode of deformation, a decrease in arterial oxygen-gas tension was apparent. It was associated with ...
Bradley B L - - 1980
Nine sedentary men 21 to 35 yr of age took part in a physical conditioning program involving regular aerobic exercise over a period of 6 to 8 wk. There was significant improvement in indexes of cardiorespiratory fitness. Ventilatory and mouth occlusion pressure responses to CO2 at rest and during threadmill ...
Lewis S M - - 1980
Recent studies suggest pH sampled by arterial chemoreceptors may not equal that sampled by external pH electrodes, because the uncatalyzed hydration of CO2 in plasma is a slow reaction (t 1/2 approximately 9 S). The importance of this reaction rate to ventilatory control (particularly during exercise) is not known. We ...
Sue D Y - - 1980
Although exercise testing is useful in the diagnosis and management of cardiovascular and pulmonary diseases, a rapid comprehensive method for measurement of ventilation and gas exchange has been limited to expensive complex computer-based systems. We devised a relatively inexpensive, technically simple, and clinically oriented exercise system built around a desktop ...
Matalon S V - - 1980
Alveolar exchange of a gas is governed by the ventilation-perfusion ratio (VA/Q) and the Ostwald partition coefficient for that species. We altered the Ostwald coefficients for O2 and CO2 by considering an animal breathing water or a fluorocarbon (FC-80) and studied the effects on gas exchange. Among our conclusions are ...
Weissman M L - - 1980
To determine the role of reflex discharge of afferent nerves from the working limbs in the exercise hyperpnea, 1.5- to 2.5-min periods of phasic hindlimb muscle contraction were induced in anesthetized cats by bilateral electrical stimulation of ventral roots L7, S1, and S2. Expired minute ventilation (VE) and end-tidal PCO2 ...
Klocke R A - - 1980
Steady-state CO2 excretion was measured in isolated blood-free rabbit lungs perfused with bicarbonate solutions. CO2 in the expired ventilation was either present initially in the perfusate as dissolved CO2 or produced from bicarbonate during pulmonary capillary transit. The two components were separated by measurement of simultaneous acetylene excretion. Bovine carbonic ...
Auchincloss J H - - 1980
A series of experiments was undertaken in a total of 95 adult subjects, of whom 25 had coronary artery disease, to evaluate the extrapolation (Defares) CO2 rebreathing method vs. the equilibrium (Collier) method for estimating mixed venous CO2 tension. Collier values were corrected for the downstream effect, whereas Defares values ...
Clark J M - - 1980
Nine young athletes performed treadmill exercise at average VO2 levels of 1.08, 1.78, 3.00, and 3.57 l/min while exposed to inspired PCO2 levels of 0, 10, 20, 30, and 40 Torr. The average slope of the VE-PACO2 relationship increased significantly from 3.59 to 4.70 l.min-1.Torr-1 in the transition from rest ...
Casaburi R - - 1980
The effects of hyperoxia on ventilatory and gas exchange dynamics were studied utilizing sinusoidal work rate forcings. Five subjects exercised on 14 occasions on a cycle ergometer for 30 min with a sinusoidally varying work load. Tests were performed at seven frequencies of work load during air or 100% O2 ...
Mitchell G S - - 1980
We compared the ventilatory response to elevated PICO2 with the response to elevation of dead space volume (delta VD) in anesthetized, hyperoxic chickens. In the first experimental series (I), PICO2 was varied between 0 and 26 Torr. In a second series (II), delta VD was raised between 0 and 17 ...
Leitch A G - - 1980
Neither propranolol (80 mg) nor metoprolol (100 mg) give orally to eight normal subjects altered mean ventilatory responses to carbon dioxide or to moderate graded exercise. Incremental doses of the drugs to totals of 320 mg propranolol and 400 mg metoprolol also did not effect these ventilatory responses. Both drugs ...
Kiley J P - - 1980
Adult White Pekin ducks were exercised at three work levels on a treadmill at speeds of .9, 1.47, and 2.16 km/hr for 20 min with a 90 min rest period following each exercise period. Blood gas and pH analyses were performed on samples simultaneously withdrawn from the brachial artery and ...
Duffin J - - 1980
The sensitivity of the ventilatory response to carbon dioxide in hyperoxia during light (25 W) exercise was compared to that at rest in 14 volunteers. The method used was that of rebreathing. Two factors were found to produce artefactual changes in the slope of the response during exercise. First, breath-by-breath ...
Gardner W N - - 1980
1. The pattern of breathing during the approach to the steady state following step changes of end-tidal P(CO2) and P(O2) has been determined in normal conscious human subjects. Three types of step were studied: (a) steps of P(A, CO2) against a constant background of hyperoxia (P(A, O2) approximately 200), an ...
Kerem D - - 1980
The extent of hypercapnia in oxygen-breathing subjects was investigated during rest and exercise (650 kpm/min). Divers, ex-divers, and non-divers were studied. Carbon dioxide retention was judged by end-tidal Pco2 values achieved after a few minutes at each state. End-breath-hold (EBH) PAco2 was also measured in the two states to assess ...
Ward S A - - 1980
Effects of increased external dead space (VD) on ventilatory control in steady-state exercise were determined in three healthy adults. The subjects performed cycle ergometer exercise on six occasions, each with a different VD (range: 0.1--1.0 liter); work rate was incremented every 5 min by 15--20 W. Minute ventilation (VE), CO2 ...
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