bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow field and mass transport analysis in arteries with longitudinal ridges
Authors: Back L. H. , Crawford D. W. , Barndt R.
Published: December 2017

Recent observations have indicated that the earliest lesions of atherosclerosis frequently take the form of longitudinal and helical ridges in arteries of man. Since longitudinal vortices are expected to be present in the troughs between the longitudinal ridges, an analysis was carried out to investigate the three-dimensional flow field and the trasport of lipoproteins and oxygen molecules to arterial walls in the presence of such vortices. The calculations revealed that local hypoxia and lipoprotein accumulation mayoccur at the ridges, leading to subsequent intimal thickening and ridge growth. Higher shear stresses, calculated in the troughs between ridges, may also partially damage the endothelium and lead to intimal thickening and subsequent merging of the ridges. Meaningful measurements are needed in vivo to determine the strength of the vortices, their time-varying behavior, and the actual transverse variations in shear stress, oxygen transport, and lipoprotein accumulation from trough to ridge regions, in order to appraise the present findings and to learn more about the observed progressive thickening and widening of ridges with increasing degrees of intimal thickening and atherosclerosis.
Arterial lactate responses in dogs made apneic or breathing nitrogen
Authors: Cain S. M.
Published: December 2017

O2 stores are kept more intact in apnea than in N2 breathing which removes O2stores from the body. If lactate moves readily into the circulation, arterial lactate should rise sooner with N2 breathing than with apnea because tissue O2 is lowered faster. This was tested in 10 anesthetized, paralyzed dogs made hypoxic both ways. Arterial and mixed venous blood were sampledevery minute until circulation began to fail. Calculated changes in O2 stores would have supported control V O2 for 1.3 min with N2 and 2.7 min with apnea. The PVO2 at those times were 23.1 and 20.1 Torr. Although arterial lactate rose sooner with N2 than with apnea, the mean values for lactate increase for both N2 and apnea were fitted by a single curvilinear relation with PVO2. The PVO2 at which lactate first rosores were depleted. Latent period for lactate rise, therefore, was nearly the same as that for development of tissue hypoxia.
Role of ketone bodies in nonshivering thermogenesis in cold-acclimated rats
Authors: Maekubo H. , Moriya K. , Hiroshige T.
Published: December 2017

The role of ketone bodies (KB) in nonshivering thermogenesis was investigated in warm- and cold-acclimated rats with and without norepinephrine (NE) loads. NE-induced calorigenesis, as evidenced by changes in rectal temperature, was highly developed in cold-acclimated rats, but the levels of blood KB and free fatty acids (FFA) remained almost unaltered. In contrast, FFA turnover rate in cold-acclimated rats under NE load was much greater than in warm-acclimated rats. Similarly, turnover rate of beta-hydroxybutyrate estimated from decay curves of the endogenous substrate in functionally eviscerated rats was significantly higher in cold- than warm-acclimated rats. Perfused livers from cold-acclimated rats produced more KB than warm-acclimated ones. No significant effect of NE load was observed in either group. Quantitative analysis shows that the turnover rate of KB in vivo essentially equals the production rate in the perfused liver when no exogenous NE is added. In contrast, under constant NE infusion the turnover rate in vivo was almost double that of the perfused liver. These results indicate that KB are an energy source as important as FFA in nonshivering thermogenesis. It may be further surmised that increased KB production in vivo, particularly in the cold-acclimated state, is affected by factor(s) other than NE.
Fetal O2 changes in response to hypoxic stress: a mathematical model
Authors: Allen W. W. , Power G. G. , Longo L. D.
Published: December 2017

We developed a mathematical model to compute the time course of PO2 changes in fetal blood vessels during hypoxia. The model represents the circulation and major organs as a system of paths and nodes. We calculated outflow O2 for a path from its inflow O2 content and its distribution of transit times. The O2 content at a given node equals the flow-weighted sum of O2 delivered by different paths. Placental O2 transfer and organ O2 consumption are related to their arterial PO2 levels. We simulated the effects of uterine contractions with Gaussian-shaped decreases in placental O2 transfer. Increasing the intensity and increasing the duration of hypoxic episodes have comparable effects. Liver O2 consumption decreases more than that of other organs during hypoxic episodes. At the peak of a contraction, fetal systemic PO2 values decrease only about one-fourth as much as those in end-capillary placental blood. This indicates that despite rapid circulation times, fetal O2 reserves protect it against severe, short term hypoxia.
Time course adaptations in cardiac and skeletal muscle to different running programs
Authors: Baldwin K. M. , Cooke D. A. , Cheadle W. G.
Published: December 2017

The effects of chronic “steady-state” and high-speed interval running were investigated on time-course changes in certain biochemical properties of cardiac and skeletal muscle fiber types of rats. Nine weeks of the interval program resulted in significant increased (15%) in both cardiac enlargement and ATPase activity of myofibrils; whereas increases in these parameters were only transient and not significant at the termination of the program involving steady-state running. Neither program induced appreciable alterations in citrate synthase and phosphofructokinase activity in cardiac muscle. In fast-twitch white fibers, “steady-state” training induced only a transient 45% increase in citrate synthase activity in contrast to a progressive twofold change with interval training. Both programs resulted in similar increases (45–50%) in citrate synthase activity in fast-twitch and slow-twitch red fibers. However, the patterns of increase for both fiber types differed between the two programs. These findings suggest that training programs incorporating elements of both “steady-state” incline and high-speed interval running can potentially induce respiratory enzyme adaptations in the greatest spectrum of rodent skeletal muscle fibers in addition to inducing adaptations to enhance contractile potential in cardiac muscle.
Antirotatory device permitting free movement in animals with several catheters
Authors: Fantino M. F.
Published: December 2017

A very simple antirotatory device permitting free movement of small and middle-sized animals is described. It allows the performance of chronic experiments in animals bearing several catheters and wires for perfusion or recording purposes. A set of eight metal plates, articulated end to end by small brackets, sets the animal's head at a fixed point on the ceiling of the cage. This device has been perfectly tolerated by rats during 2 wk to 3 mo.
Volume characteristics of extra- and intraparenchymal segments of the canine pulmonary artery
Authors: Friedman M. , Wanner A.
Published: December 2017

The volumes of the extraparenchymal segment (VpaEP) and intraparenchymal segment (VpaIP) of the pulmonary arterial tree were determined in intact anesthetized dogs during room air breathing and acute hypoxia. Total pulmonary arterial blood volume (Vpatotal) was calculated as the product of pulmonary blood flow and pulmonary arterial circulation time. An angiographic technique was used to estimate VpEP. VpaIP was calculated by subtracting VpaEP from Vpatotal. During room air breathing at functional residual capacity, mean +/- SD of VpaEP was 17.1 +/- 5.1 ml and of VpaIP was 31.7 +/- 20.8 ml, representing 40% and 60%, respectively, of Vpatotal. Vpatotal increased 22.2 +/- 10.5 ml during lung inflation, with proportional increases in VpaIP and VpaEP. VpaEP was found to be influenced equally by changes in transmural pulmonary arterial and transpulmonary pressures. Acute hypoxia was accompanied by an increase in pulmonary vascular resistance and a decrease in volume distensibility of the extraparenchymal segment. Vpatotal increased 76% without changes in the relative volume distribution of VpaEP and VpaIP. These findings can be best explained by active vasomotion with an increase in down-stream pulmonary vascular resistance.
Comparison of measures of forced expiration
Authors: Ligas J. R. , Primiano F. P. , Saidel G. M. , Doershuk C. F.
Published: December 2017

Theoretical relationships among a number of parameters were derived for idealized timed vital capacity (TVC) and maximal expiratory flow-volume (MEFV) curves to determine a minimal set of independent parameters. Normal pediatric subjects and those with cystic fibrosis were studied to verify these relationships experimentally. The average flow over the middle half (FEF25–75%) of the forced vital capacity (FVC) and flows at various exhaled percentages of the FVC (FEF50%, FEF75%), as well as moments of the TVC and MEFV curves were computed. From the TVC moments, a mean transit time (MTT) and an index of dispersion (ID) were also calculated. The minimum information needed to detect pulmonary mechanical changes associated with obstructive lung disease requires at least two reproducible measures: one related to the mean slope (e.g., FEF25–75%/FVC or MTT) and the other to the shape (e.g;, ID) of the effort-independent portion of the MEFV curve.
Ventilatory response in the fetal lamb following peripheral chemodenervation
Authors: Woodrum D. E. , Standaert T. A. , Parks C. R. , Belenky D. , Murphy J. , Hodson W. A.
Published: December 2017

Carotid infusions of sodium cyanide solution and perfusions of hypoxemic or hypercapnic fetal blood were done before and after peripheral chemoreceptor denervation. Step changes in PaO2 ranged from -11 to -22 Torr; step changes in PaCO2 ranged from +17 to +42 Torr. The cyanide dose was 0.2 mg/kg per loop system. Control perfusions consisted of 25 ml of fetal blood without changes in pH and blood gases. A ventilatory response occurred in the majority of all experimental perfusions regardless of innervation status of the peripheral chemoreceptors. No response occurred with control perfusions. There was a marked variability in the time of onset of ventilatory activity with a delay of greater than 10 s occurring following most perfusions. These studies demonstrate that the fetus has an attenuated ventilatory response to chemical stimuli and that hypoxia stimulates ventilation in the absence of peripheral chemoreceptors.
Parameters for assessing vibration-induced cardiovascular responses in awake dogs
Authors: Bhattacharya A. , Knapp C. F. , McCutcheon E. P. , Edwards R. G.
Published: December 2017

The vibration parameters for assessing the response of the cardiovascular system to whole-body vibration were studied. Six awake, chronically instrumented canines were restrained with their spines vertical, and exposed to GZ sinusoidal vibration of 2–12 HZ for a constant peak acceleration amplitude of +-1.0 G. Vibration exposures of 30 s with intervening recovery periods of 2 min were employed. The following variables were measured: mean heart rate (MHR), stroke volume (SV), mean aortic flow (MAF), mean aortic pressure (MAP), the peak net force transmitted to the canine/body weight (PNF/BW), and the vibration platform frequency (ft), displacement, and acceleration. The percentage change from control (no vibration) of MAF varied linearly with PNF/BW for all cases. MAF also varied linearly with the log MHR/ft for the number of dogs which primarily changed MHR during the vibration exposures. The response of MAP was minimal in all cases, indicating a decrease in total peripheral resistance with increasing PHF.
Changes in plasma glucose, FFA, corticosterone, and thyroxine in He-O2-induced hypothermia
Authors: Wang L. C. , Peter R. E.
Published: December 2017

Unanesthetized, male rats were exposed to normal air (NA), or NA and a 4 h-exposure of He-O2 (79% helium, 21% oxygen) at ambient temperature (Ta) of 22 or - 10 degrees C. Blood samples from each individual were taken from a chronically implanted carotid cannula at 1) preexposure, 2) during exposure, 3) 2.5 h after exposure, and 4) 19–20 h after exposure. Exposure to He-O2 at 22 degrees C caused an increase in plasma free fatty acids (FFA) and corticosterone of 45% and 49%, respectively, with little change in plasma glucose and thyroxine. Exposure to He-O2 at 10 degrees C for 3 h invariably induced hypothermia with body temperature (Tb) decreased to 23.7 +- 0.5 degrees C (N = 10). During hypothermia, plasma glucose, FFA, and corticosterone were significantly higher (P LESS THAN 0.05) than those at preexposure and those after exposure to NA at -10 degrees C. During spontaneous recovery from hypothermia, at Ta = 19 degrees C and NA, glucose, corticosterone, and thyroxine returned to normal, but FFA remained significantly higher than at preexposure. The ability of animals to rewarm spontaneously from hypothermia and the quick return of metabolic substrates and hormones to normal after rewarming indicates the preservation of regulatory mechanisms for metabolism at depressed Tb when hypothermia is induced by He-O2 and cold.
Urinary catecholamine excretion on induction to high altitude (3,658 m) by air and road
Authors: Hoon R. S. , Sharma S. C. , Balasubramanian V. , Chadha K. S.
Published: December 2017

In a preliminary pilot study we had reported a significant difference in urinary catecholamine excretion between symptomatic and asymptomatic individuals inducted to high altitude by air. The present study covers slower induction by road; 25 lowlanders ascended from 1,800 to 3,658 m in 50 h and 33 similar subjects covered the journey in 6 h. They were studied according to the protocal used in the initial study. None of the 58 subjects inducted by road developed symptoms of high-altitude illness. Their urinary catecholamine excretion remained normal during the 10 days' stay at high altitude. These findings lend support to our earlier contention that there might be a relationship between increased sympathoadrenal activity and high-altitude illnesses.
Evaporation of sweat from sedentary man in humid environments
Authors: Berglund L. G. , Gonzalez R. R.
Published: December 2017

Physiological and sensory responses were observed in four male subjects while they were seated on a balance. The chamber temperature always equaled mean skin (Tsk)(34–36 degrees C), thus eliminating all sensible heat transfer. Ambient water vapor pressure (Pa) was increased in steps from 10 to 40 Torr. Tests at air velocities from 0.1 to 2.4 m/s were conducted with subjects nude and clothed. Esophageal temperature (Tes) and Tsk, heat rate (HR) and weight loss (M) were measured throughout the 2.5-h tests. After each 25-min humidity step subjects recorded their warm discomfort, sensation of sweating, and thermal sensation. Results: Tsk, HR, and M were unaffected by humidity until critical Pa (P a crit) was reached above which M decreased and Tsk and HR increased rapidly. P a crit decreased with clothing and decreasing velocity. Tes remainded relatively constant throughout the tests. Sweating, discomfort and temperature sensations increased gradually with increasing Pa. Above P a crit sweating and discomfort sensations accelerated markedly. Mass transfer coefficients and clothing vapor conductance factors were evaluated. Skin wettedness at Pa crit decreased from 74% at 0.1 m/s to 35% at 2.4 m/s.
Hematologic changes after two exposures to 6.7 ATA air at three-day intervals
Authors: Jacey M. J. , Gonzales A. , Tappan D. V.
Published: December 2017

Hematologic parameters were studied in human subjects exposed to various diving regimens. A series of exposures in a dry chamber to a simulated depth of 188 ft of seawater gauge (fswg), 6.7 ATA, utilizing compressed air, were carried out according to standard Navy diving tables. The subjects were serially followed for a control period prior to diving and subsequently for up to 1 wk. Little significant change occurred except for alterations in some platelet factors. In another series of experiments, the single excursion was followed by a second dive to 188 fswg 3 days later, again with appropriate hematologic monitoring. A pronounced eosinopenia and increased clotting times were observed soon after reaching the surface. Platelet depletion associated with increased clumping and elevated megathrombocyte levels persisted long after the second excursion. A latent hemodilution also developed 3--5 after the second dive. These findings clearly demonstrate that repeated hyperbaric exposures produce additive effects and further suggest that no diving procedure is completely innocuous.
Estrous cycle variations of food and water intake in rats in the heat
Authors: Attah M. Y. , Besch E. L.
Published: December 2017

Effects of heat and estrous cycle on food and water intake and on the kinetics of water metabolism were studied in Holtzmann rats, 12 adult females per group. The animals were housed individually in metabolic cages, in series, in a controlled-environment room at (24.5 degrees C) followed by two experimental temperatures (29.2 degrees C and 34.0 degrees C). In all cases relative humidity was 50% and the photoperiod 12L:12D (L = 0600--1800 h). Intake of food and water, available ad libitum, were measured and recorded daily for at least five consecutive estrous cycle (about 25 days). Water turnover was measured using tritiated water. The results indicate that the experimental conditions constituted stressful environments for the rats. Their corticosterone levels were significantly (P less than 0.01) elevated and a relative lymphopenia and neutrophilia (P less than 0.01) were observed. Additionally, food intake was decreased and water intake increased, both significantly (P less than 0.01). Body water turnover was increased (P less than 0.01) while body water pool size and the biological half-life for 3H2O were reduced. However, the cyclic variation of food and water intake and its relationhsip to the estrous cycle were unchanged.
Oxygen consumption and ventilation of dogs during passive and active exercise
Authors: Russo A. K. , Tarasantchi J. , Griggio M. A.
Published: December 2017

A comparison was made between the influence of passive and active exercise on the energy metabolism (EM) and respiratory parameters (RP) of dogs: respiratory minute volume and ventilatory equivalent for O2. Passive exercise was performed in 24 dogs, anesthetized with pentobarbital sodium and morphine or ketamine hydrochloride and pentobarbital sodium, by moving the four limbs at constant frequencies of 25, 45, or 80 movements/min before and after curarization. Active exercise was induced in 35 animals by electric stimulation of the quadriceps and triceps muscles or of the distal ends of femoral and radial nerves at the same frequencies previously indicated. Values obtained for EM and RP during passive exercise were not significantly different from those obtained during resting conditions; active exercise caused a significant increase which was directly proportional to the frequencies of limb movement. Our results indicate that passive muscle movement induces no alteration in O2 consumption and the possible relfexes generated in these experimental conditions were not apparently important on ventilatory control. In active movements, over the range of the frequencies studied, there is a proportional increase in O2 consumption followed by a corresponding increase in ventilation.
Effects of thoracic dorsal rhizotomies on the respiratory pattern in anesthetized cats
Authors: Shannon R.
Published: December 2017

Experiments were conducted to determine if thoracic wall proprioceptor afferents are involved in the modulation of respiratory activity during eupnea. The effects of elimination of thoracic wall afferents (thoracic dorsal rhizotomies (TDR) on tidal volume (VT), frequency (f), inspiratory time (ti) and expiratory time (te) were studied in vagotomized cats anesthetized with diallylbarbituric acid (Dial). Dorsal rhizotomies 1–12 resulted primarily in a decreased VT and ti, and an increased f. Further experiments were performed to determine if these changes in respiratory pattern could be correlated with known reflexes from the middle and lower intercostal muscles, or lungs, via thoracic dorsal roots. Afferents from these sources were eliminated by TDR 5–9, 10–13, and 1–4. TDR 1–4 had no significant effect on the respiratory pattern. TDR 5–9 and TDR 10–13 produced changes similar in direction to TDR 1–12. The results indicate that: a) afferents 1–4 from the upper intercostal muscles and lungs (sympathetic afferents) do not contribute significantly to the control of the spontaneous respiratory rhythm, and b) afferents via the middle thoracic roots, 5–9, and the lower thoracic roots, 10–13, contribute significantly to the rhythm. The results do not completely correlate with known intercostal reflexes, but it is suggested that elimination of intercostal muscle proprioceptor afferents is responsible for the observed effects of thoracic dorsal rhizotomies.
Stress-free equilibrium volume of the lung
Authors: Vawter D. L.
Published: December 2017

An experimental procedure was developed to measure the stress-free equilibrium volume of intact lobes from the lung of the dog. The procedure eliminates body, gravitational, interfacial, and externally applied forces to study the contribution of the tissue forces. The equilibrium gas volume was found to be 1.74 +/- 0.20 times the tissue volume and was independent of the volume history. This is smaller than the minimal air volume found by others and about one half the functional residual capacity (FRC) volume. The lung was found able to resist compressive loading implying a “finite buckling load” for the aveolar septa. A simple calculation shows the length-to-thickness ratio to be 7.1 at the stress-free equilibrium volume.
Effect of lung inflation and hypoxia on pulmonary arterial blood volume
Authors: Quebbeman E. J. , Dawson C. A.
Published: December 2017

Isolated cat lungs were perfused with constant blood flow. During control conditions (Pa02, 100 Torr), pulmonary artery pressure increased as the lungs were inflated. Hypoxia (Pa02, 22 Torr) increased arterial pressure. However, as the lungs were inflated arterial pressure fell. Thus, the magnitude of the hypoxic pressor response was reduced by inflation. During control conditions, arterial volume (ether bolus method) increased with increasing transpulmonary pressure. Hypoxia decreased arterial volume, and the increase in arterial volume with inflation was somewhat less than that during control conditions. When the influences of vascular and transpulmonary pressures were examined independently by changing one while holding the other constant, increasing transpulmonary pressure increased arterial volume beyond that which could be accounted for by changes in the differences between arterial and pleural pressure. However, this influence of transpulmonary pressure did not appear to be altered by hypoxia. Thus, while hypoxia decreased arterial volume at all levels of lung inflation, it had relatively little effect on the influence of interdependence between the pulmonary arterial bed and the surrounding lung tissue.
High-sensitivity device for continuous measurements of tissue O2 uptake
Authors: Biron R. , Dittmar A.
Published: December 2017

An analysis system for continuous measurements of O2 uptake by rat diaphragm during several hours is described. The tissue was set in a chamber where a medium was flowing at a known and constant flow rate, temperature, and partial pressure of oxygen (PO2). The decrease in PO2 of the medium was measured with a Clark O2 cathode at the outlet of the chamber. To increase the sensitivity of the system and the signal-to-noise ratio of the measurements, a sweeping device was designed. It provided homogenization of the medium in the chamber. The main characteristics of this analysis system are a) a sensitivity of +/-0.2% of the mean PO2 value of the perfused medium, +/-0.8% of the mean O2 uptake of rat diaphragm, b) a linearity of +/-1.75% in the range of 0+/-200 Torr, c) a stability of +/-0.38% of the initial PO2 value, and d) a time constant of 8 min 30 s. This type of system can be used for high-sensitivity measurements of O2 uptake of any tissue after adaptation of the chamber and of the medium flow rate.
Semiautomatic blood pressure monitor utilizing an electronic sphygmomanometer
Authors: Winn R. , Hildebrandt J. R. , Hildebrandt J.
Published: December 2017

A semicontinuous but noninvasive blood pressure monitoring system is described. It consists of a commercial electronic sphygmomanometer which utilizes a microphone under an occluding arm cuff to detect the Korotkoff sounds, a pressure transducer, and a simple gating circuit. The gate passes the cuff pressure signal to a recorder only when a proper Korotkoff sound is detected. The cuff is rapidly inflated to just above the anticipated systolic pressure, then deflated at a steady rate of 2–6 Torr/heartbeat. When diastolic pressure is passed, the cuff is fully deflated momentarily before repeating the cycle. Systolic and diastolic pressures can be recorded up to 3 or 4 times/min. Spurious signals are rejected by the electronics which process the output of the microphone. This allows the use of the system in experiments on exercising man and in environments where unwanted signals exist. The system offers greater versatility than commercial semiautomatic pressure monitors, at less than half the cost.
Mechanisms by which histamine stimulates rapidly adapting receptors in dog lungs
Authors: Vidruk E. H. , Hahn H. L. , Nadel J. A. , Sampson S. R.
Published: December 2017

The stimulant effect of histamine on intrapulmonary rapidly adapting receptors was studied in anesthetized, paralyzed, artificially ventilated dogs, to determine whether it was dependent on contraction of airway smooth muscle. Single- or few-afferent fiber recordings were made from small strands dissected from the otherwise intact vagus nerve. Aerosols of histamine increased both receptor discharge and tracheal pressure (Pt). In 27 experiments, isoproterenol prevented the increase in Pt but not in receptor activity induced by histamine. In another 32 experiments, acetylcholine (ACh) increased Pt to a greater extent than did histamine, whereas histamine increased receptor discharge more than ACh. When given as aerosol directly to the vicinity of the sensory receptor via a fiber bronchoscope, histamine stimulated 12 receptors, whereas ACh and buffer solution did not. Isoproterenol reduced slightly the stimulant effect of locally applied histamine on 8 receptors. We conclude that smooth muscle contraction is not essential for stimulant effects of histamine on rapidly adapting receptors in dog lungs, and that histamine acts directly on the receptors to increase their activity.
Albumin clearance from alveoli: tissue permeation vs. airway displacement
Authors: Meyer E. C. , Ottaviano R. , Higgins J. J.
Published: December 2017

In anesthetized, ventilated dogs, clearance of 2 +/- 0.2 ml alveolar-instilled 1% isosmolar [125I]albumin ([125I]RISA) was separated into bulk airway displacement and transalveolar tissue permeation by the use of collimated external detectors and by sampling of blood and lymph. The detectors were positioned perpendicular to the plane of bronchial drainage, and collimator resolution was characterized by a 50% decrease in count rate for a 5-mm lateral (transbronchial) instillate shift. Detector signals demonstrated no airway shift in 10 dogs studied, the signal decay equaling [125I]RISA absorption determined by lung homogenates. The mean rate constants of [125I]RISA lung clearance and epithelial permeation were 4.08 X 10(-4)-min-1 and 5.48 X 10(-4)-min-1, respectively. The diffusional permeability coefficient of alveolar epithelium for albumin was 4.06 X 10(-9) CM-S-1. Absorbed [125I]RISA was separated into blood and lymph components by collecting lymph from the right lymphatic duct (RLD) and thoracic duct. Mean blood/lymph removal ratio was 6.3/1, and correlated with plasma/RLD lymph steady-state albumin concentration ratios in individual animals. Over a mean observation period of 5.4 h, an average of 12.3% [125I]RISA was cleared from the instilled region. The data suggest that this amount was cleared by permeation; there was little evidence of airway clearance.
Effects of O3 inhalation during exercise on pulmonary function and blood biochemistry
Authors: DeLucia A. J. , Adams W. C.
Published: December 2017

Page 75: A. J. DeLucia and W. C. Adams. “Effects of O3, inhalation during exercise on pulmonary function and blood biochemistry.” Page 79: substitute at the top of the left-hand column: In our experiments, the ratio of O3 dosages would simply be the ratio of Ve exercise/Ve rest. For the mean ventilatory volumes achieved at 25%, 45%, and 65% Vo2 max work loads, the dosage ratios would be 2.6, 4.0, and 6.0 times resting, respectively.
Muscle metabolism and cardiac function of the myopathic hamster following training
Authors: Sembrowich W. L. , Knudson M. B. , Gollnick P. D.
Published: December 2017

The effect of 18 wk of treadmill running on skeletal muscle metabolism and myocardial function of normal and myopathic hamsters was examined. BIO 14.6 hamsters could tolerate an exercise intensity of about 18 m/min for 40 min, 5 days/wk. Further increases in speed or number of bouts per day resulted in a falloff in performance. Normal hamsters could tolerate higher speeds and longer exercise bouts. Exercise did not change the severity of lesions of either the heart or skeletal muscle of the myopathic hamsters. A training effect was evidenced by increased succinate dehydrogenase activity in the soleus muscle. Cardiac function was evaluated as contractility measured from left ventricular pressure curves and expressed as (dP/dt)/kP. The results suggested that cardiac contractility was not as severely depressed in the trained BIO 14.6 strain of hamsters as in nontrained controls. However, (dP/dt)/kP was lower in the trained myopathic animals than in normal hamsters. ATP, CP, and glycogen levels were lower in myopathic hamsters with the lowest values occurring in the trained group. These data demonstrate that the BIO 14.6 strain of hamster can tolerate exercise training and that such training may have a positive effect on cardiac function.
Regional distribution of VA/Q in man at rest and with exercise measured with krypton-81m
Authors: Harf A. , Pratt T. , Hughes J. M.
Published: December 2017

The regional distribution of ventilation-perfusion ratio (VA/Q) in the lung was obtained from the continuous inhalation and infusion of 81mKr. With this short half-life isotope (13 s) serial measurements were made in six young normal subjects during spontaneous breathing, with minimal radiation exposure. At rest in the upright position the apical zone had a high VA/Q, but over the lower two thirds VA/Q distribution was relatively homogeneous. There was a slight increase towards the base. During exercise at 50 and 100 W the distribution became more uniform but there was more obvious than at rest. These distributions are consistent with a zone of reduced basal blood flow (zone IV) which becomes more marked on exercise. Apical blood flow was followed during the transition from rest to exercise and recovery. There was a large (40–150%) increase within 30 s of starting to pedal at 50 W, but little change thereafter.
Effects of prostaglandin F2alpha on lung mechanics in nonasthmatic and asthmatic subjects
Authors: Brown R. , Ingram R. H. , McFadden E. R.
Published: December 2017

Prostaglandins have been implicated as secondary pharmacologic mediators in allergic bronchial asthma. We have studied the effects of the intravenous infusion of prostaglandin F2alpha (PGF2alpha) on pulmonary mechanics in nonasthmatic and asthmatic volunteers. Before and during the infusion, measurements were made of total lung capacity and its subdivisions, static deflational transpulmonary pressure-volume relationships (PV), and maximal expiratory flow-volume curves with air and after a washing of an 80% helium-20% oxygen mixture. In both groups, PGF2alpha caused significant decreases in vital capacity and maximal flow and increases in residual volume. There were not significant differences between groups in either the absolute magnitude or the percent change in the variables, a result which may have been due to the similarity of the pulmonary mechanics in both groups prior to infusion. Changes in density dependence were bidirectional in both groups, indicating that relative contributions of large and small airways to flow limitation changed differently among individuals. The single between-group difference in responses noted was a leftward shift of the PV curve in the asthmatics, suggesting recoil of the lung which occurs in asthma.
Selected brain amino acids and ammonium during chronic hypercapnia in conscious rats
Authors: Weyne J. , Van Leuven F. , Kazemi H. , Leusen I.
Published: December 2017

Glutamic, aspartic, and gamma-aminobutyric acid (GABA), glutamine, and ammonium were measured in the brains of unanesthetized normocapnic and hypercapnic (10% CO2; 5 min to 3 wk) rats. Hypercapnia increased glutamine and GABA and decreased glutamic and aspartic acids. Changes occurred within 1 h and were maintained during the observation period of 3 wk. On return to normocapnia amino acid concentrations were almost normal after 1 h. Based on the time course it is concluded that intracerebral hypercapnia is more likely the stimulus for change than acidosis. Ammonium content was unchanged for at least 1 h after the onset of hypercapnia but increased thereafter. Experiments in which glutamine synthesis by brain was impeded by inhibiting the enzyme glutamine synthetase favor the hypothesis that the rise of ammonium content in hypercapnia is initially not seen because of increased glutamine synthesis. The changes observed may have a role in metabolic pH homeostasis of brain tissue and may also be relevant to the modified brain excitability in hypercapnia.
Continuous distributions of specific ventilation recovered from inert gas washout
Authors: Lewis S. M. , Evans J. W. , Jalowayski A. A.
Published: December 2017

We describe a new technique for recovering continuous distributions of ventilation (V) as a function of tidal ventilation/volume ratio (V/V0) from the nitrogen washout. The analysis yields a continuous distribution of V as a function of V/V0 represented as fractional ventilations of 50 compartments plus dead space. The procedure was verified by recovering known distributions from data to which noise had been added. Using an apparatus to control the subject's tidal volume and FRC, mixed expired N2 data gave the following results: a) the distributions of young, normal subjects were narrow and unimodal with a mean ln standard deviation of 0.56 plus or minus 0.13; b) those of subjects over age 40 were broader (ln SD 0.86 plus or minus 0.19) with more poorly ventilated units; c) patients with pulmonary disease of all descriptions showed enlarged dead space; d) patients with cystic fibrosis showed multimodal distributions with the bulk of the ventilation going to overventilated units; and e) patients with obstructive lung diseases fell into several classes, three of which are illustrated. These results suggest that our approach is well suited for clinical investigation.
Distribution oand pharmacological release of histamine in canine lung in vivo
Authors: Nisam M. R. , Zbinden A. , Chesrown S. , Barnett D. , Gold W. M.
Published: December 2017

We have examined the physiological effects of stored mediators released from airways by compound 48/80 aerosols in anesthetized dogs. In 13 dogs, both mast cell numbers and tissue histamine were related inversely to bronchial internal diameter (P less than 0.0001). Compound 48/80 aerosols degranulated mast cells and decreased histamine content (-29.0 +/- 10.0%; mean +/- SE) in 5–10 mm bronchi, but not in 3–4 mm bronchi or lung parenchyma. This was associated with increased plasma histamine (31.8 +/- 18.4 ng/ml), increased airflow resistance (Rrs: + 452 +/- 257%), decreased lung compliance (-28 +/- 10%), and decreased arterial blood pressure (-41 +/- 6.5%) at 2 min. The increased Rrs was reversed by beta-adrenergic agonists, indicating it was caused by bronchial smooth muscle contraction; prevented by chlorpheniramine, indicating it was caused by histamine action on H1-receptors; and augmented and prolonged by propranolol, suggesting that histamine triggered sympathetic mechanisms which modulated the effect of 48/80. This experimental approach permits the study of mechanisms in vivo which may be involved in the sequence of reactions initiated by antigen-IgE interaction. However, the latter involve not only stored mediators, but also unstored mediators, neural reflexes, and complex cellular interactions.
Quantitative changes in permeability of rat lung epithelium in lung edema
Authors: Gardiner T. H.
Published: December 2017

The pulmonary absorption of 14C-labeled urea, mannitol, inulin, and dextran was measured in vivo in anesthetized rats with alpha-naphthylthiourea (ANTU)-induced (5 mg/kg, ip) lung edema. At 1 h after ANTU treatment, the absorption of mannitol was significantly increased; in 4-h ANTU-treated animals, the absorption of urea was unchanged, whereas the absorption of mannitol, inulin and dextran was increased markedly compared to controls. Although disappearance of each solute from control lungs could be described by a single, first-order rate, absorption time curves for mannitol and inulin showed at least two components in edematous lungs: a fast component(s) and a slower, first-order component; fast-component rates for the two saccharides appeared to be similar; the slow-component rate for each compound was not significantly different from its control rate. The results suggest that fast-component absorption in ANTU-treated rats represents a fraction of instilled solute which entered damaged areas of lung where the porosity of the absorbing membranes was markedly increased, whereas slow-component absorption occurred from normal areas of lung.
Acute dehydration: body water distribution in acclimated and nonacclimated Psammomys obesus
Authors: Horowitz M. , Samueloff S. , Adler J. H.
Published: December 2017

Body water distribution after “acute dehydration” treatment (37 degrees C) was studied in Psammonys obesus before and after acclimation at 34 +/- 1 degrees C for 16–18 days. Determinations of water compartment volumes were performed on anaesthetized (thiopental sodium) nephrectomized animals. Plasma volume (PV) and extracellular volume (ECV) were measured by T-1824 and [14C]inulin, respectively. Total body water was determined after desiccating the animals. Albumin outflux was calculated from the half-life (T1/2) of T-1824 and total plasma albumin mass. Nonacclimated animals conserved PV as long as dehydration did not exceed 10–11% loss of body wt. This conservation was at the expense of ECV and was associated with diminished albumin outflux (T1/2 T-1824 approached infinity). With increased dehydration PV retention failed and a resumption of albumin outflux occurred. Acclimation resulted in diminished albumin outflux in both control and dehydrated animals (T1/2 T-1824 approached infinity). Most of the water lost during dehydration was of intracellular origin. It was concluded that reduction in permeability of the capillary bed during dehydration and acclimatization plays an important role in PV and ECV regulation.
Computerized measurement of pulmonary conductance and elastic recoil
Authors: Colebatch H. J. , Nail B. S. , Ng C. K.
Published: December 2017

A system devloped for on-line measurement of transpulmonary pressure, gas flow at the mouth, change in expired volume and plethysmograph volume uses a minicomputer to control a multiplexed analog to digital converter. The computer identified samples as static or dynamic values by monitoring a voltage activating a solenoid valve, used to close the airway. Analysis of these samples by other task-specific programs yielded the static deflation pressure-volume (PV) curve, the conductance-recoil pressure, GL-Pst(L), relationship and the maximum expiratory flow-volume (MEFV) curve; the MEF-Pst(L) curve and conductance upstream from the equal pressure point were derived. The PV relationship was represented by a fourth-order polynomial and the GL-Pst(L) relationship by linear regression. In 11 subjects the results obtained using on-line data collection, compared with manual analysis of oscillograph recordings, showed small differences in static compliance and in the maximum Pst(L); but overall the two methods showed excellent agreement. Besides advantages of speed and objectivity, this system facilitates a more rigorous analytical treatment of elastic recoil and conductance.
Respiratory flow integrator with improved stability
Authors: Deno N. S. , Barlett H. L. , Buskirk E. R.
Published: December 2017

A circuit was designed for integrating respiratory flow signals over time to produce volume signals. The circuit involves a simple integrator and three compensation subcircuits which control integrator drift caused by ambient temperature changes, flow signal base-line errors, and random signal errors. A functional unit built according to the circuit design requires initial adjustment, but no further adjustment before or during sustained use. Integration errors are typically less than 1%. The only flow signal requirements are that they be bidirectional and within the human physiological frequency range.
Physiological and biophysical limits to work in the heat for clothed men and women
Authors: Kamon E. , Avellini B. , Krajewski J.
Published: December 2017

Heat-acclimated, lightly clothed men and women (four of each) walked on a treadmill at 25% and 43% VO2 max, respectively, (M =194 W.m-2), under seven air temperatures (Ta) ranging from 36 to 52 degrees C. Each experiment involved 1 h of fixed and a 2nd h of progressively increasing ambient vapor pressure (Pa). The relative steady state of rectal temperature (Tre), mean skin temperature (Tsk), and heart rate (HR) reached in the 1st h were forced upward during the 2nd h by the rising Pa. The critical air vapor pressure (Pcrit) was identified by the Tre point of inflection for each Ta. One man did not fully reach steady state, but inflection could be determined for his physiological responses. The mean values of all points of inflection were calculated for Tre, Tsk, and HR. Significant sex difference in HR was found only by excluding the results of the one man. Tre and Tsk showed no significant difference between men and women. The coefficient for evaporative heat transfer (he), which could be derived using the Pcrit for the low Ta range, was 14.5 +/- 2.2 W.m-1 Torr-1.
Servo control of end-tidal CO2 in paralyzed animals
Authors: Smith D. M. , Mercer R. R. , Eldridge F. L.
Published: December 2017

We are reporting an electronic circuit which uses the peak end-tidal CO2 signal from a rapid infrared CO2 analyzer to vary the motor rate of a fixed volume respirator. It contains variable gain and a lag compensation network which permits critical damping to prevent oscillation. The CO2 analyzer, circuitry, and respirator are connected in a closed-loop servo system that allows automatic control of the CO2 level. The system's gain and performance are such that it can accommodate large changes of CO2 return to the lungs with no more than +/- 0.5 Torr carbon dioxide pressure (PCO2) error signal. It has proved useful in experiments on neural respiratory control in paralyzed animals where it is desired to keep PCO2 constant despite changes in cardiac output and venous and CO2 return to the lungs, and to monitor the approximate magnitude of these changes.
Effect of altitude on dietary-induced thermogenesis at rest and during light exercise in man
Authors: Stock M. J. , Norgan N. G. , Ferro-Luzzi A. , Evans E.
Published: December 2017

Measurements of metabolic rate and the thermic response (specific dynamic action) of a 400-kcal liquid meal were made in six subjects at rest and during light exercise. The tests were conducted before (LA1) and after (LA2) a 3-wk sojourn (HA1, HA2, HA3) at 3,650 m on the Monte Rosa. Fasting metabolic rate at rest increased inittally and then fell, as did fasting and fed exercising metabolic rates. The fall in metabolic rates, but not the initial increases, can be ascribed to the change in body weight. Resting thermic responses at altitude were only slightly lower than normal, although peak values were significantly depressed at HA2 (P less than 0.05). The mean exercising thermic response was also significantly lower at HA2 (P less than 0.05) but recovered in HA3 and LA2. In the time taken for thermic responses to decrease and recover there were interindividual differences that were best explained by the previous altitude experience of the subjects. The possibility of a cardiovascular shift during hypoxic exercise causing depression of postprandial metabolism is discussed.
Oxygen consumption during constant-load exercise
Authors: Hagberg J. M. , Mullin J. P. , Nagle F. J.
Published: December 2017

Previous investigators have reported that oxygen consumption (VO2) continues to rise after the initial 2- to 3-min transient period of exercise when work exceeds approximately 60% of VO2 max. The purpose of this investigation was to examine the possible causes of this slow rise in VO2. Eighteen subjects exercised for 20 min at 65% and at 80% of VO2 max on the bicycle ergometer. VO2, ventilation (VE), and respiratory exchange ratio were monitored by a continuous computer-based system. Blood lactate concentration and rectal temperatures were measured at 2- to 3-min intervals during the exercise. VO2 increased significantly from the 5th to 20th min of exercise in 81% of the tests at both levels of work intensity. The magnitude of the rise was not different for the two work loads. No evidence was found to support the lactacid explanation proposed for this rise. Increased temperature could account for 30% of the rise; the estimated cost of increased VE could account for 30 and 81% of the rise at the two work loads. The sum of these factors could account for 60 and 111% of the rise in VO2 at the 65 and 80% of VO2 max work loads.
A comparison of exercise responses in stairclimbing and cycling
Authors: Oldenburg F. A. , McCormack D. W. , Morse J. L. , Jones N. L.
Published: December 2017

A free-paced 14.8-m stairclimb was compared to cycle ergometry at equivalent power outputs in six normal subjects. Heart rate (HR), inspiratory flow (VI) andd oxygen saturation in arterial blood (Sao2) were analyzed continuously, carbon dioxide output (Vco2) and oxygen consumption (Vo2) for the duration of exercise, and rebreathing mixed venous carbon dioxide pressure (Pvco2), capillary blood gases, and lactates at the completion of exercise. The average power output was 1,394 kpm/min sustained for 54.8 s. The HR and Vo2 responses were not significantly different between the two forms of exercise. VI was 20.3% less stairclimbing (P smaller than 0.005). A fall in Sao2 of 31.1% +/- 2.7) occurred in stairclimbing compared to 1.2% (+/- 2.1) in cycle ergometry. Differences in Sao2 between stairclimbing and cycling correlated with differences in VI (r = 0.80); falls in Sao2 could be prevented by overbreathing during stairclimbing or induced by controlled underbreathing during cycling. Vco2 and postexercise lactate levels were less stairclimbing (P smaller than 0.005 and P smaller than 0.01), as were Pvco2 measurements. The findings are consistent with a lower CO2 flow to the lung during stairclimbing than in cycling, which results in a lower alveolar ventilation and a consequent fall in Sao2.