bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of energy metabolism from respiratory functions alone
Authors: Bursztein S. , Saphar P. , Glaser P. , Taitelman U. , de Myttenaere S. , Nedey R.
Published: December 2017

To monitor variations of energy metabolism on-line a system which accurately measures VO2 and VCO2 is described. The calculation of the energy metabolism usually requires knowledge of nitrogen production. This paper presents a formula that allows calculation on-line on the energy metabolism with a maximum relative error of 4% as function of VO2 and VCO2 only. Some experimental results in normal subjects are presented.
Depression of serotonin clearance by rat lungs during oxygen exposure
Authors: Block E. R. , Fisher A. B.
Published: December 2017

The effect of oxygen (O2) exposure on the ability of the isolated, perfused rat lung to clear serotonin (5-hydroxytryptamine, 5-HT) from the perfusate was evaluated in normal or vitamin E-deficient Sprague-Dawley rats. Rats were exposed to 100% O2 at 1 ATA for 4–48 h. Lungs were subsequently isolated, artificially ventilated, and perfused in a recirculating system with Krebs-Ringer bicarbonate solution, pH 7.4 containing 3% bovine serum albumin and 0.25 muM [14C] 5-HT. 5HT clearance was calculated from the disappearance rate of [ 14C] 5-HT from the perfusate. In normal rats exposed to 100% O2, there was a progressive reduction in the clearance of 5-HT with increasing duration of O2 exposure. Compared to lungs from air-exposed controls, clearance was depressed 20% (P less than 0.01) after 18 h, 22% (P less than 0.01) after 24 h, and 35% (P less than 0.001) after 48 h. With vitamin E-deficient rats, the reduction in 5-HT clearance occurred after a shorter exposure time and was of greater magnitude than in rats on a normal diet. Depression of 5HT clearance by the lungs is an early alteration of lung function fue to hyperoxia and is potentiated by vitamin E deficiency. The most likely mechanism for the depression of 5-HT clearance is interference with the transport properties of lung endothelium.
Variations in evaporation and body temperatures during sleep in man
Authors: Henane R. , Buguet A. , Roussel B. , Bittel J.
Published: December 2017

The thermal balance in man was investigated during nocturnal sleep in neutral and warm environments (from 32 to 39.5 degrees C, 45%rh). Changes of body temperatures and skin evaporation were continuously monitored throughout the whole night. In neutral conditions (32 and 34 degrees C) body temperature and skin evaporation decreased during the night, following the circadian rhythm deltaT sk = -0.34 degrees C; deltaT re = -0.52 degrees C;deltaE = -12 W-m-2. In warm conditions, body temperatures and evaporation remained steady. Marked fluctuations of body temperatures and evaporation occurred synchronously with the rapid eye movement (REM) periods. Each REM period induced phasic increase of Tsk reaching +2 degrees C in some cases, with a cessation of evaporation. Tre showed upward and downward rhythmical waves synchronously with REM sleep occurrence. The nocturnal variations of thermal balance were characterized by two rhythms: a basal circadian rhythm and superimposed on it a rhythm conditioned by occurrence of REM sleep every 80–90 min. The phasic changes of body temperatures and evaporation only appeared with REM's. The results suggest that the nervous integrative function conditioning the patterns of sleep, conditions also the phasic cyclic changes of thermoregulatory function.
Fluid and electrolyte shifts in women during +Gz acceleration after 15 days' bed rest
Authors: Greenleaf J. E. , Stinnett H. O. , Davis G. L. , Kollias J. , Bernauer E. M.
Published: December 2017

Twelve women (23–34 yr), comprising a bed-rest (BR) group of eight subjects and an ambulatory (AMB) group of four subjects, were centrifuged after 14 days of ambulatory control (C),after 15 days of a 17-day BR period, and on the third day of recovery (R). Venous blood was taken before and after the third +3.0 G acceleration run (1.8 G/min). Relative to (C), the +Gz tolerance after BR was reduced -49.0% (P less than 0.05) in the BR group and -38.7% (NS) in the AMB group; during (R) the BR group regained up to 89.4% and the AMB group up to 87.1% of their (C) tolerances. In each of the three test periods, the shifts in plasma Na, Cl, PO4, and osmotic contents, which accompanied +Gz, followed the outward shift of plasma volume (PV). The correlation of the shift of PV during acceleration with the +Gz tolerance was 0.72 (P less than 0.01). During acceleration, the PV and electrolyte loss for both groups after BR was about half the loss of (C) and (R). Compared with (C) and (R) values, potassium shifts were variable but the mean corpuscular volume and mean corpuscular Hb contents and concentrations were unchanged during all +Gz runs; The results indicate that: 1) the higher the (C) + Gz tolerance, the greater the tolerance decline due to BR; 2) relative confinement and reduced activity contribute as much to the reduction in tolerance as does the horizontal body position during BR; 3) bed-rest deconditioning has no effect on the erythrocyte volume during +3.0 Gz; and 4) about one-half the loss in tolerance after BR can be attributed to PV and electrolyte shifts.
Influence of fasting on the lung
Authors: Gail D. B. , Massaro G. D. , Massaro D.
Published: December 2017

We examined the following in fed rats and in rats fasted for 72 h: 1) the dipalmitoyl lecithin (DPL) content of lung lavage fluid and of the remaining lung tissue, 2) descending air and saline pressure-volume curves of excised lungs, and 3) the volume density of granular pneumocyte lamellar bodies. Lung tissue DPL was decreased by 27% and lavage DPL was decreased by 40% in lungs of fasted rats. The decreased lung DPL content was associated with a 20% decrease in the volume density of lamellar bodies of granular pneumocytes. In spite of the decrease in lavage DPL content, air pressure-volume curves of excised lungs were the same as curves of lungs of fed rats. Saline pressure-volume curves of excised lungs were also the same in fed and fasted rats. The amount of lavage DPL obtained from both fed (1.1 +/- 0.1 mg, n=6) and fasted (0.7 +/- 0.1 mg, n=7) rats exceeded the theoretical minimum amount of DPL (0.5 mg) required for a monomolecular film to cover the alveolar surface of the rat at functional residual capacity. If we assume that lavage DPL represents mainly DPL lining the alveolus (surface film and hypophase) the data suggest that there is an alveolar reserve of DPL above that amount needed to maintain normal alveolar stability.
Experimental study of convective heat transfer coefficient for the human body in water
Authors: Boutelier C. , Bougues L. , Timbal J.
Published: December 2017

The steady-state convective heat transfer coefficient in water has been determined by partitional calorimetry for 17 nude subjects. Four water velocities were investigated: 0, 0.05, 0.10, and 0.25 m-s-1; and the water temperature ranged from 33.7 to 18 degrees C. In still water, hc varied from 43 W-m-2-degrees C-1 in thermoneutral conditions and a shivering rate less than 90 W-m-2 to 54 W-m-2-degrees C-1 in cold water with a shiver rate greater than 110 W-m-2. The equation, hc=0.09 (Gr-Pr)0.275, give a good approximation of this coefficient. In stirred water and for the same limits of shivering, hc can be expressed as a power function of the velocity: hc = 272.9 v0.5 and hc = 497.1 v0.65, respectively. These equations show that the flow is laminar in thermoneutral conditions and intermediate between laminar and turbulent in cold water. A study of the influence of skinfold on the magnitude of hc shows that higher values of this coefficient were obtained for thin subjects than for fat ones, concomitant with more intense shivering. The utilization of a theoretical physical model for computations of hc gave excessively high values because such methods do not embody the body shape factor and reduction of water flow adjacent to the skin.
Ouabain-sensitive liver and diaphragm respiration in cold-acclimated hamster
Authors: Horwitz B. A. , Eaton M.
Published: December 2017

The in vitro respiratory rates of liver and diaphragm from hamsters were compared before and after prolonged cold exposure (5 degrees C, 3–4 wk). In the presence or absence of glucose, respiratory rates were elevated in both tissues from the cold-acclimated hamsters, and these cold-induced increases were significantly reduced by ouabain. This ouabain inhibition is consistent with the hypothesis that cold exposure of these rodents stimulates the energy demands of the Na+/K+ transport system in liver and diaphragm, with these demands providing a driving force, at least in part, for respiration and accompanying cellular thermogenesis.
Cardiac responses to moderate training in rats
Authors: Codini M. A. , Yipintsoi T. , Scheuer J.
Published: December 2017

Left ventricular (LV) performance was studied in 30 rats conditioned by swimming and in 27 sedentary controls. Hearts were studied in the open chest both during sinus rhythm and during atrial pacing. Afterload was increased by occlusion of the aorta. Sinus rates were 328 beats/min in sedentary and 300 in conditioned animals (P less than 0.01). During ejection (E), peak left ventricular systolic pressure (PLVSP) and maximum LV dP/dt were significantly higher in conditioned than in sedentary animals. When data from hearts matched for similar heart rates were compared, increased LV performance was still seen during aortic obstruction in conditioned animals. Performance at pacing rates up to 400 beats/min was similar in hearts from conditioned and sedentary animals. At pacing rates above 400 beats/min cardiac performance was less in sedentary than in the conditioned animals. These data illustrate that although base-line cardiac performance may be the same in rats conditioned by a moderate swimming program and in sedentary animals, cardiac reserve is improved by the swimming program.
Interaction of lung volume and chemical drive on respiratory muscle EMG and respiratory timing
Authors: Kelsen S. G. , Altose M. D. , Cherniack N. S.
Published: December 2017

The effect of increased FRC on the change in respiratory muscle electrical activity (EMG) and the duration of inspiration (Ti) and expiration (Te) produced by increases in chemical drive (i.e., progressive hypercapnia and isocapnic hypoxia) was assessed in 15 anesthetized, spontaneously breathing dogs. FRC was raised by applying continuous positive pressure (4 and 8 cmH2O) to the airway. Progressive hypercapnia and hypoxia were produced by rebreathing techniques. At any PCO2 or PO2, increases in FRC decreased diaphragm EMG (D); increased abdominal muscle EMG (AB); and prolonged Te without affecting Ti. The effect of increased FRC on D, AB, and Te diminished as PCO2 increased or PO2 decreased. The effect of sustained increases in lung volume in the absence of phasic changes was assessed by performing airway occlusion for a single inspiration during rebreathing at both control and increased FRC. The effects of increases in FRC were present during airway occlusion but were eliminated by vagotomy. We conclude, therefore, that tonic vagal stimulation produced by increases in FRC modified the change in respiratory muscle electrical activity and timing produced by increasing chemical drive.
Phagocytosis: quantification of rates and intercellular heterogeneity
Authors: Kavet R. I. , Brain J. D.
Published: December 2017

We present a method which permits analysis of phagocytic behavior in small samples of macrophages. Both overall phagocytic kinetics and intercellular variability in particle uptake were measured. Macrophages lavaged from Syrian golden hamster lungs were incubated (5 min at 37 degrees C) with 2- to 4-mum plastic particles at 4.6, 6.9, 9.1, and 16.0 X 10(6) part./ml. Harvested macrophages ranged from 0.6 to 4.0 X 10(6) cells per animal. To concentrate the cells and separate them from cell-free substrate after termination of phagocytosis, 30–60% of each flask's contents were centrifuged (400 X g, 20 min) atop a Metrizamide subphase (34% wt/vol, rho = 1.18). Cells were collected from the interface, fixed, and visually scored for number of particles phagocytized. Phagocytic rates followed Michaelis-Menten kinetics with Vmax = 0.63 +/- 0.18 (SEM) part./viable cell per min and Km = 8.5 +/- 2.7 (SEM) X 10(6) part./ml. In every case (23/23 flasks from 6 animals) particle uptake exhibited greater (P less than 0.01) cell-to-cell variability in avidity for substrate than the Poisson distribution would predict from mean number of particles phagocytized per viable cell.
Anodal block of medullated cardiopulmonary vagal afferents in cats
Authors: Thoren P. , Shepherd J. T. , Donald D. E.
Published: December 2017

In anesthetized cats examination was made of the conditions under which the application of DC current to a mixed nerve permits determination of whether a reflex response is mediated by medullated or nonmedullated afferents. The following precautions should be observed. The nerve must be stripped of its sheath and bleeding avoided. The anode should be 6 mm distant from the cathode. The temperature of the mineral oil surrounding the nerve should be 30–32 degrees C to avoid activation of nonmedullated fibers during the block. The major limitation is a time- and frequency-dependent block of nonmedullated fibers which makes the technique suitable only for differentiating between medullated fibers and nonmedullated fibers with low frequency traffic. Observing these criteria, anodal block of the cervical vagus in sino-aortic denervated cats resulted in a mean rise in aortic pressure of 8 Torr; subsequent cold block caused a further mean rise of 30 Torr. Thus 80% of the total increase in aortic pressure could be ascribed to interruption of vagal C-fiber activity.
Alveolar pressure and lung volume as determinants of net transvascular fluid filtration
Authors: Bo G. , Hauge A. , Nicolaysen G.
Published: December 2017

We have investigated the influence of changes in alveolar pressure (PAlv) and in lung volume on the net transvascular fluid filtration rate (FFR). The preparation was isolated, perfused zone III rabbit lungs. In observation periods the outflow pressure was kept constant at a level generally causing net filtration. All pressures were measured relative to atmospheric. FFR was measured by continuous monitoring of preparation weight. Elevation of Palv at constant lung volume caused reversible reductions in FFR, also at constant capillary hydrostatic pressure (Pa-V less than 2 Torr). Increases in lung volume at constant PAlv caused reversible increases in FFR. When both PAlv and Ptp were increased a reduction in FFR was seen in the majority of cases. We conclude that at constant pulmonary arterial pressure, the size and the direction of the influence of positive airway pressure on FFR depend on the relative change in lung volume and in alveolar pressure per se. Under the present experimental conditions a rise in PAlv will be transmitted to interstitial fluid pressure and affect the transvascular fluid balance.
Metabolism of the apoproteins in pulmonary surfactant
Authors: King R. J. , Martin H. , Mitts D. , Holmstrom F. M.
Published: December 2017

Two proteins having nominal molecular weights of 35,000 and 10,000 daltons are found in pulmonary surfactant. Although experiments on their immunological properties suggest that they share antigenic determinants, their metabolic relationship is unknown. To study this question we injected [14C]palmitic acid or L-[3H]leucine into the femoral vein of 59 puppies. We killed the animals 30 min to 68 h after injection and purified surface-active material from the endobronchial lavage fluid. We isolated the 35,000 apoprotein, the 10,000 apoprotein, and the saturated phosphatidylcholines in surfactant and measured their specific activities at various times after injection. We found that the 35,000 apoprotein appears in alveolar surfactant with the same time course as saturated phosphatidylcholine but is cleared more rapidly than is the lipid. The specific activity of the 10,000 apoprotein reaches a maximum after that seen for the 35,000 apoprotein and decays with the same turnover time as that of the lipid. The kinetic data suggest that the 10,000 apoprotein is a metabolic product of the 35,000 apoprotein. They are not consistent with the possibility that the 10,000 apoprotein is an artifact of nonspecific degradation during preparation.
Glucose-induced decrease in glucagon and pinephrine responses to exercise in man
Authors: Galbo H. , Christensen N. J. , Holst J. J.
Published: December 2017

Seven men ran at 60% of individual maximal oxygen uptake to exhaustion during beta-adrenergic blockade with propranolol or without drugs. After propranolol administration the increases during exercise in plasma glucagon and epinephrine concentrations as well as the decrease in plasma glucose concentrations were faster than in control experiments. When euglycemia was maintained by glucose infusion during beta-adrenergic blockade, glucagon and epinephrine responses to exercise, although not abolished, were markedly reduced. The diminution of the exercise-induced decline in glucose concentrations correlated significantly with the diminution of the glucagon as well as the epinephrine responses. Thus decreased glucose concentrations may significantly enhance the secretion of glucagon and epinephrine during prolonged exercise in man. Since the diminution of the glucagon response produced by glucose infusion was not accompanied by significant alterations in the levels of nonesterified fatty acid (NEFA) and glycerol, increased glucagon secretion does not seem to be a major determinant of lipolysis during exercise in man. During glucose infusion, glycogen utilization rates in muscle (n = 4) tended to decrease, whereas carbohydrate combustion rate and concentrations of norepinephrine, insulin, alanine, and lactate were unchanged.
Human tecg changes during prolonged hyperbaric exposures breathing N2-O2 mixtures
Authors: Wilson J. M. , Kligfield P. D. , Adams G. M. , Harvey C. , Schaefer K. E.
Published: December 2017

In an effort to determine whether hyperbaric exposures while breathing N2-O2 mixtures have an effect on cardiac depolarization and repolarization, electrocardiograms of 10 divers participating in four N2-O2 saturation dives were analyzed. In all cases, a decline in heart rate was observed upon compression to saturation depth (20–30%); a slow adaptation and return of heart rate toward normal was observed in those dives where the depth and environmental parameters remained constant. twhenever excursion dives were performed, the heart rate responded by decreasing on deeper excursions and increasing on upward excursions. Hyperbaric bradycardia disappeared after 8 days at pressure during the saturation dives at 50 and 60 feet seawater gauge (fswg), but was still present at this time at 200 fswg. The magnitude of the hyperbaric bradycardia produced by excursion dives following saturation at depth was influenced by the state of adaptation of heart rate. Decompression was uniformly accompanied by a rapid increase in heart rate resulting in a significant elevation in the postdive period. Alterations in myocardial repolarization as evidenced by Q-T interval, ST, and T wave changes were observed. Development of slight right ventricular conduction delay compatible with right ventricular strain was noted in four of the divers during the two deepest dives to 100 and 198 fswg. During the latter dive, progressive decrease in P wave amplitudes and eventual loss of P waves resulting in an apparent nodal rhythm was observed in one diver. Multiple premature ventricular contractions occurred in another diver. These observations, along with the reports by other authors, suggest that the different variables associated with the hyperbaric environment--gas density, pressure, inert gas--have a definite effect on the pacemaker activity of the heart and myocardial depolarization and repolarization.
Hematology, viscosity, and respiratory functions of whole blood of the lesser mouse deer, Tragulus javanicus
Authors: Snyder G. K. , Weathers W. W.
Published: December 2017

Blood samples from the lesser mouse deer were examined for hematology, viscosity, oxygen dissociation curve, and magnitude of the Bohr effect. Red corpuscle dimensions, determined under oil immersion with an ocular micrometer, averaged 2.2 micron while the cell counts averaged 53 million/micronl blood, and the packed cell volume averaged 31.2%. Blood hemoglobin concentration averaged 11.2 g/100 ml and the calculated mean cell hemoglobin concentration was 38 g/100 ml. The relative viscosity of the mouse deer plasma was 1.97 and increased in a nonlinear manner with hematocrit to 100 at 80% packed cell volume. Oxygen-hemoglobin equilibrium curves, determined with a mixing technique at 37 degrees C and 10, 36 and 71 Torr PCO2, have the same configuration observed in blood from mammals in general. The P50 of the mouse deer blood at pH = 7.40 is 34 Torr and the Bohr effect (deltalog P50/deltapH) is -0.483. The mouse deer have blood hematocrits which are well below the hematocrits observed in mammals with larger erythrocytes, but similar to the blood hematocrits observed in other mammals with small erythrocytes. We suggest that the low hematocrit is an adaptation which circumvents the hemodynamic problems associated with a high blood viscosity and that, in the mouse deer, the expected concomitantly low total blood hemoglobin concentration is compensated by a higher than average mean cell hemoglobin concentration.
Glucose loading and dehydration in the camel
Authors: Yagil R. , Berlyne G. M.
Published: December 2017

Five female bedouin camels were subjected to large infusions of glucose, both when water was readily available and following 10 days of water deprivation. When the camels were hydrated the extra glucose was readily given off in the urine with only a slight increase in blood levels. Following dehydration, the blood glucose levels increased greatly while the urinary excretion was limited. Dehydration led to decreased blood insulin levels, while glucose infusion led to increased levels. The data show that the acclimatization of the camel to dehydration is not only a question of long-term adaption to desert conditions but that even following acute nonphysiological stress, i.e., glucosuria, excess loss of body water was prevented.
Effect of high-altitude exposure for 10 days on stroke volume and cardiac output
Authors: Hoon R. S. , Balasubramanian V. , Mathew O. P. , Tiwari S. C. , Sharma S. C. , Chadha K. S.
Published: December 2017

Resting stroke volume and cardiac output of 50 normal healthy sea-level residents (group A) were estimated by the noninvasive technique of electrical impedance plethysmography. They were then airlifted to an altitude of 3,658 m and serial estimations carried out at 0–4 h and 5–8 h and on the 2nd, 3rd, 4th, 5th, and 10th days. The subjects were brought back to sea level and studied for up to 5 days. Thirty permanent residents of high altitude (group B) and sixteen lowlanders temporarily resident at high altitude (group C) were also subjected to similar studies. It was found that resting stroke volume and cardiac output of group A started falling immediately on arrival at high altitude, reached the minimum on the 3rd day and tended to improved on the 4th and 5th day, but showed a secondary fall on the 10th day. The reduction in stroke volume in this group was not fully compensated by tachycardia. On return to sea level the cardiac output normalized immediately, the stroke volume on the 2nd day. At sea level goup A had values similar to group B and at high altitude to group C.
Hemoconcentration during isotonic handgrip exercise
Authors: Ohira Y. , Ito A. , Ikawa S.
Published: December 2017

Three healthy males performed an intense isotonic handgrip ergometer exercise to exhaustion (approximately 10 min). Serum water, serum total protein (STP), and hematocrit were determined in the venous blood taken from the brachial veins in both exercised and nonexercised arms before exercise and 10 s, 1, 2, and 3 min after the termination of exercise. Although no sweat was observed, hemoconcentration occurred in both arms. The peak degree of water loss in the nonexercised arm, however, was delayed and lower than that in the exercised arm. Further, three healthy males were exposed to a sauna (76 degrees C) for 20 min to test the effect of sweating on hemoconcentration in the absence of physical movement. Venous blood was withdrawn from the forearm vein before the sauna, after 5 min in the sauna, and at 3 and 30 min during sitting recovery period. No hemoconcentration was observed during the course of the experiment.
Adaptations to endurance training at three intensities of exercise
Authors: Dohm G. L. , Beecher G. R. , Stephenson T. P. , Womack M.
Published: December 2017

This study was undertaken to investigate the influence of exercise intensity (running speed) on a number of alterations that are known to occur with exercise training. Rats were trained on three treadmill running schedules: 20 m/min, 27 m/min, and 35 m/min for 1 h/day. After 6 wk, lean body mass and body fat content were decreased to the same extent in all three trained groups. Thus, exercise appears to lower body fat by some mechanism that is not related to the amount of energy expended during exercise. Heart and adrenal gland weight-to-lean body mass ratios were increased by training. Heart weight-to-lean body mass ratio increased with increasing intensity of exercise but the adrenal weight-to-lean body mass ratio was independent of exercise intensity. Training increased muscle succinate dehydrogenase activity to the same extent in all three trained groups which suggests that the adaptation in respiratory capacity is not altered greatly by the intensity of training.
Supersaturation by counterperfusion and diffusion of gases
Authors: Hills B. A.
Published: December 2017

Gaseous supersaturation can be induced under steady-state conditions when two inert gases are transmitted in opposite directions across any system comprising a diffusion barrier adjacent to a zone of limited convective capacity. This has many implications for bubble formation in vivo and can explain the occurence of symptoms of decompression sickness without decompression.
Effect of physical training on control mechanisms of lipolysis in rat fat cell ghosts
Authors: Shepherd R. E. , Sembrowich W. L. , Green H. E. , Gollnick P. D.
Published: December 2017

Fat cell ghosts and homogenates of fat cells were used to study the influence of training on the regulatory system for lipolysis in adipose tissue of female rats. A training effect was identified from elevated succinate dehydrogenase activities in the soleus and plantaris muscles. Neither basal nor maximal (NaF-stimulated) adenylate cyclase activities per mg protein of fat cell ghosts were altered by training. Fluoride-stimulated adenylate cyclase activity per microgram DNA was lower in the trained than untrained group. Adenylate cyclase activities in response to norepinephrine expressed either on a per mg protein or per microgram DNA basis were lower (P less than 0.05) in fat cell ghosts from trained rats. Phosphodiesterase activity was higher (P less than 0.05) in fat cell ghosts from trained rats for cyclic AMP concentrations of 1–-5.0 micrometer. The apparent Km's of phosphodiesterase were 1.19 and 2.0 micrometer of cyclic AMP for the untrained and trained groups, respectively (P less than 0.05). Protein kinase activity in the supernatant fraction of homogenates of fat cells was unchanged due to training. The overall effect of training was to blunt the system for cyclic AMP production in rat adipocytes. This may explain, at least partially, the lower plasma free fatty acid levels observed in trained compared to untrained persons during submaximal exercise.
Prostaglandin synthesis inhibition restores hypoxic pulmonary vasoconstriction
Authors: Alexander J. M. , Nyby M. D. , Jasberg K. A.
Published: December 2017

Hypoxic pulmonary vasoconstriction in blood-perfused isolated dog lungs progressively diminishes with repeated hypoxic challenges. We investigated the role of prostaglandins in effecting the decay of the hypoxic response by using a double perfusion preparation that could separately perfuse the right and left lungs of a single dog. Degeneration of this response was reversed by the addition of prostaglandin (PG) synthesis inhibitors, aspirin, or indomethacin. Various PG's known to be produced by the lung (PGE1, PGE2, and PGF2alpha), were infused, and only PGE1 abolished hypoxic pulmonary vasoconstriction. Since other workers have shown that lungs can synthesize and release PG's in response to various stimuli, we postulate that PGE1 synthesis in isolated lungs may increase and thereby cause the degeneration of the hypoxic response. The addition of aspirin or indomethacin could inhibit the synthesis of PGE1 and thereby restore hypoxic pulmonary vasoconstriction.
Comparative effects of endoperoxide PGH2 and an analog on the pulmonary vascular bed
Authors: Kadowitz P. J. , Gruetter C. A. , McNamara D. B. , Gorman R. R. , Spannhake E. W. , Hyman A. L.
Published: December 2017

The effects of the prostaglandin endoperoxide, PGH2, and a stable endoperoxide analog were compared on the canine pulmonary vascular bed under conditions of controlled blood flow. The analog produced dose-related increases in lobar arterial and small vein pressure when injected into the perfused lobar artery. The increase in resistance in response to the analog was greater during retrograde perfusion than during forward perfusion. These data suggest that the analog increases resistance to flow by constricting pulmonary veins and upstream vessels. The increase in resistance was similar when the lung was perfused with dextran or blood and the response was not different when the lung was ventilated or collapsed. The response was notattenuated by indomethacin, an inhibitor of prostaglandin synthesis. These data suggest that the response to the analog is not related to changes in bronchomotor tone, platelet aggregation, or enhanced prostaglandin synthesis. Although the analog was a potent pressor substance, PGH2 itself produced only small increases in pulmonary vascular resistance. However, PGH2 had greater contractile activity than the analog on isolated helical segments of canine intrapulmonary vein. The present study suggests that endoperoxides may represent an active form of the prostaglandins in the lung but that their effects would be localized in the tissue in which they are formed because of their extremely short biologic half-life.
Effect of transpulmonary and vascular pressures on rate of pulmonary edema formation
Authors: Goldberg H. S. , Mitzner W. , Batra G.
Published: December 2017

The effect of transpulmonary pressure (Ptp) on rate of extravascular fluid accumulation in isolated canine left lower lobes perfused at constant vascular pressures was investigated. Changes in rate of extravascular fluid accumulation were estimated by changes in rate of slow weight gain. Mean inflow pressure (Ppa) was constant at 34 cmH2O. Mean outflow pressure (Ppv) was constant at either 27.2 cmH2O or 13.6 cmH2O. When increasing Ptp is associated with a derecruitment of vascular beds as the lung changes from predominantly zone III toward zone II, or zone I, there is a decrease in rate of weight gain. When increasing Ptp is not associated with a derecruitment of vascular beds, it is impossible on the basis of these experiments to predict the change in rate of weight gain.
Adaptation to short-term respiratory effects of ozone in men exposed repeatedly
Authors: Hackney J. D. , Linn W. S. , Mohler J. G. , Collier C. R.
Published: December 2017

To investigate whether adaptation which modifies some acute effects of ozone (O3) exposure can develop in humans, six male volunteers with respiratory hyperreactivity were exposed in a controlled environment chamber to 0.5 ppm O3 2h/day for 4 successive days under conditions stimulating ambient pollution exposures. One subject showed little measurable response, while five showed function decrement on exposure days 1–3 which was largely reversed by day 4. Symptom responses generally paralleled the physiological responses. These results suggest that at least some humans adapt to O3 exposure at concentrations occurring in severe community air pollution episodes, to the extent that obvious acute respiratory effects are prevented. Other adverse effects of O3 may not be prevented by this adaptation.
Pulsating bubble technique for evaluating pulmonary surfactant
Authors: Enhorning G.
Published: December 2017

Surface tension is determined with an apparatus which records pressure across the surface of a bubble, expanded in the sample liquid and communicating with ambient air. The disposable sample chamber, with a volume of 20 microliter, communicates with a pulsator and a pressure transducer. The volume displacement of the pulsator's moving piston is hydraulically geared down 1,000 times, which gives the pulsator a stroke volume of 0.43 microliter. When this volume is moving into the sample chamber, it causes the bubble radius to change from a maximum of 0.55 mm, accurately measured through a microscope, to a minimum of 0.4 mm. The pulsator speed is usually 20 rpm, but it can be changed from 0.02 to 80 rpm. From the known pressure gradient across bubble surface, and bubble radius, surface tension is calculated with the law of Laplace.
Glucose oxidation during prolonged exercise evaluated with naturally labeled [13C]glucose
Authors: Pirnay F. , Lacroix M. , Mosora F. , Luyckx A. , Lefebvre P.
Published: December 2017

By use of naturally enriched [13C]glucose as metabolic tracer, the utilization of exogenous glucose ingested during muscular exercise was investigated. Four subjects walked on an uphill treadmill for 2 h, and three other for 4 h. The energy expenditure, close to 50% of the individual maximum Vo2,, varied from 1.9 to 2.1 liters of O2/min, while the heart rate ranged between 142 and 165 beats/mm. The subjects who were on a mixed diet and had fasted overnight, were given 100 g of naturally labeled [13C]glucose. Following this intake? the expired CO2 became rapidly enriched in carbon-13. The increase was observed as early as 15 min after the oral intake, and reached a maximum within 1–2 h, when utilization of exogenous glucose varied between 500 and 650 mg/min, representing as much as 55% of the carbohydrate metabolism and 24% of the total energy expenditure.

glucose metabolism; man; mass spectrometry; stable isotopes
Determinants of the prescriptive zone of industrial workers
Authors: Kuhlemeier K. V. , Miller J. M. , Dukes-Dobos F. N. , Jensen R.
Published: December 2017

The prescriptive zone is the range of climates in which man's body temperature is independent of climatic conditions. The environmental temperatures which define the upper limit of the prescriptive zone (ULPZ) at different work rates were determined in 46 clothed, healthy, male industrial workers; some of the men were job acclimated to heat and some were not. They performed a total of 653 work bouts of low, medium, or high intensity in environments ranging from 11 to 35 degrees C corrected effective temperature (CET) (8–37 degrees C wet bulb globe temperature). Heart rates (HR) and rectal temperatures (Tre) were measured after 1 h of work. The ULPZ was calculated from Tre data. HR's showed a similar pattern of response as Tre's except that the inflection point corresponding to the ULPZ occurred at different environmental temperatures at most of the experiment conditions. About one-third of the work bouts were performed in the summer months and the remainder in the winter. The ULPZ decreased with increasing work rates. At high, but not low, work rates, men who were exposed to heat in the performance of their jobs were more heat tolerant than men who were not heat acclimatized. Both groups were found to be more heat tolerant in the summer months than in the winter.
Hematologic responses to carbon monoxide and altitude: a comparative study
Authors: Thomas M. F. , Penney D. G.
Published: December 2017

Groups of 40- and 90-day-old rats were exposed to 500 ppm CO (HbCO=31–43%) and simulated altitude (15,000 ft). Resulting hematologic changes were monitored after 1 day, 1 wk, 3–4 wk, and 9–11 wk of exposure. The two treatments resulted in similar changes in hemoglobin (Hb) and hematocrit ratio (Hct) in the young rats, while in the older group there were several small, but significant differences in these parameters. Mean corpuscular hemoglobin concentration (MCHC) fell 12.4–15.1% during the 1st wk of exposure in all groups except the young altitude rats, which remained at the control value. The former groups returned to control levels by the 3rd to 4th wk of exposure. Red cell 2,3-diphosphoglycerate (2,3-DPG) increased 21.6–26.1% above control during 3–4 wk of altitude exposure, but later (9–11 wk) returned toward control levels. CO exposure resulted in a sharp decrease in 2,3-DPG after 1 day of exposure only in the young rats. 2,3-DPG level progressively decreased with age in control rats. The effects of CO and altitude although similar in several respects (i.e., Hb, Hct, MCHC) differ with regard to red cell 2,3-DPG.
Aspects of on-line digital integration of pulmonary gas transfer
Authors: Bernard T. E.
Published: December 2017

Digital computers are often used in work physiology to find pulmonary gas transfer on a breath-by-breath basis. A measurement procedure was simulated to determine the effects of sample rate, signal noise levels, and numerical filters on the digital calculations. The results indicated that a trapezoidal rule integration at a sample rate of 30 Hz with no numerical filter can provide satisfactory data. The flow rate and concentration signals should not be out of phase by more than 25 ms. The simple computational procedures give accurate results while minimizing the memory requirements and computation time.
Role of conducting airways in partial separation of inhaled gas mixtures
Authors: Horsfield K. , Davies A. , Cumming G.
Published: December 2017

A positive (hollow) cast of the bronchial tree was made from a pig's lung. Gas mixtures containing sulfur hexafluoride (SF6) and helium (He), and SF6 and argon (Ar), were blown down the cast at two different flows, the cast having first been filled with air. Gas was sampled by a mass spectrometer probe from 1-mm-diam branches situated on short, medium, and long pathways. The front of the SF6 appeared in advance of the fronts of the He and the Ar. This relative advancement was greater a) with the SF6/He mixture than with the SF6/Ar mixture; b) at slower flows; and c) on longer pathways. With reverse flow up the cast using SF6/He there was little differences between the arrival times of the two gas fronts at either flow. These results could be explained by the effects of Taylor dispersion on gases having different diffusion coefficients.
Wave-speed limitation on expiratory flow-a unifying concept
Authors: Dawson S. V. , Elliott E. A.
Published: December 2017

The mechanism limiting forced expiratory flow is explained on the basis that a local flow velocity reaches the local speed of wave propagation at a point, called the choke point, in intrathoracic airways. This theoretical approach to the “waterfall effect” leads to selection of the analogy of constricted open-channel flow to apply to the elastic network of airway tubes. Quantitative results are derived for the case of negligible friction by use of the Bernoulli principle. Shapes predicted for the maximum-flow static recoil curves depend only upon the nature of the pressure-area curve at the choke point in the case of negligible friction; and the magnitude of the critical rate of flow depends on reference values of cross-sectional area and elastic modulus at the choke point, on gas density, and on the static recoil pressure. The present theoretical results are used to interpret previous experiments, but quantitative applicability is limited because of frictional effects and lack of knowledge of choke point conditions.
A digital computer technique for analyzing respiratory muscle EMG's
Authors: Bruce E. N. , Goldman M. D. , Mead J.
Published: December 2017

A method is described for extracting from the electromyograms of respiratory muscles a continuous signal which has primarily the periodicity of respiratory pressure and flow wave forms. The EMG is first band-pass-filtered from 50 to 500 Hz, then digitized, full-wave rectified, passed through a nonlinear voltage window to reduce noise (particularly ECG) artifacts, then low-pass filtered with a digital continuous, or moving, averager. An average wave form corresponding to one respiratory cycle is produced by ensemble averaging of the wave forms from several consecutive breaths. Diaphragmatic electromyograms from a human and from a rabbit are processed in this manner, and the effect on the processed wave forms of changes in inspired CO2 and of a change in end-expiratory lung volume are demonstrated.
An analog approach to measuring O2 uptake on-line
Authors: Cain S. M. , Donald T. C.
Published: December 2017

An analog circuit has been designed to provide a solution to the Haldane transformation that yields true O2 fraction. Incoming signals proportional to fractional concentration of CO2 and O2 in mixed expired gas are utilized in the circuit and the results are multiplied by a value proportional to ventilation. The final products are analog signals proportional to O2 uptake and CO2 output. The system is applicable to the anesthetized and paralyzed animal kept at a known constant ventilation. The final products are analog signals proportional to O2 uptake and CO2 output. The system is applicable to the anesthetized and paralyzed animal kept at a known constant ventilation. Diagrams of the circuit and expired gas collection and analysis arrangements are provided.
Anti-G suit effect of cardiovascular dynamic changes due to +GZ stress
Authors: Peterson D. F. , Bishop V. S. , Erickson H. H.
Published: December 2017

Lightly anesthetized dogs underwent 1-min exposure to +Gz acceleration without and with a bladder-type anti-G suit. Prior chronic instrumentation permitted through evaluation of cardiac dynamics. During +3 Gz acceleration all recorded dynamic variables were lowered and transient tachycardia occurred. After acceleration ceases, all pressures and dP/dt exceeded control levels. Inflation of the anti-G suit during +3 Gz eliminated the dramatic effects observed during and after acceleration stress. During +6 Gz with the anti-G suit inflated, arterial pressure and dP/dt were maintained whereas left ventricular end-diastolic pressure and total peripheral resistance were much elevated and heart rate was lower. At the onset of G stress, internal diameter of the heart always fell transiently. Otherwise, diameter was not significantly affected by any of the experimental conditions. The results suggest that the anti-G suit maintains perfusion pressure at high sustained G; however, with the anti-G suit inflated at +6 Gz, central venous pressure is dramatically elevated and heart rate depressed. Thus, beneficial effects which provide tolerance to high G are accompanied by potentially detrimental effects.
Effects of increased plasma fatty acids on glycogen utilization and endurance
Authors: Hickson R. C. , Rennie M. J. , Conlee R. K. , Winder W. W. , Holloszy J. O.
Published: December 2017

The purpose of this study was to test the hypothesis that increased availability of fatty acids could increase endurance by slowing the rate of glycogen depletion. Rats were given corn oil by stomach tube, and 3 h later an injection of heparin was given to raise their plasma free fatty acids (FFA). The rats with raised FFA were able to run approximately 1 h longer than otherwise comparable control animals before becoming exhausted (181 +/- 8 vs. 118 +/- 8 min, P less than 0.001). At the point of exhaustion, both groups were hypoglycemic and had low muscle glycogen concentrations. The fall in blood glucose occurred less rapidly in the animals with raised FFA; these rats also had significantly higher blood glycerol and beta-hydroxybutyrate concentrations than the controls. Glycogen concencentration decreased less rapidly in all three types of skeletal muscle and in liver in the animals with raised FFA than in the controls. We conclude that increased availability of fatty acids delays the development of exhaustion in rats subjected to prolonged running. It appears likely that the carbohydrate-sparing effect of fatty acids is largely responsible for the increase in endurance.
Metabolism in rat lung tissue slices: technical factors
Authors: O'Neil J. J. , Sanford R. L. , Wasserman S. , Tierney D. F.
Published: December 2017

We compared several sets of conditions used to estimate metabolism in rat lung slices. 14CO2 production from [14C]glucose, oxygen consumption, lactate production, and glucose consumption were used as measures of metabolic activity. The calculated results differed when we used 1) different techniques for estimating tissue weight, 2) tissue slices of 0.3-, 0.5-, 0.7-, and 1.0-mm thickness, 3) 95% air or 95% oxygen with 5% CO2 4) a delay after slice preparation and 4 degrees C and room temperature or periods of anoxia before incubation, 5) shaking rates of 60, 90, 120, or 150/min, 6) phosphate or bicarbonate buffers. Conditions of maximal activity were found using 95% O2 with 1.0-mm tissue slices, shaking at 120/min in phosphate buffer without periods of hypoxia or undue delays before incubation. Tissue weight should be obtained without exposure to aqueous solutions or dehydration by contact with cotton gauze or filter paper.
Longitudinal distribution of vascular resistance in the lung
Authors: Grimm D. J. , Linehan J. H. , Dawson C. A.
Published: December 2017

We have modified the low-viscosity bolus technique for determining the longitudinal distribution of pulmonary vascular resistance. A bolus of saline was introduced into the pulmonary artery of an isolated cat lung. As this low-viscosity bolus passed through the lung, a fall in inflow pressure was recorded which had a characteristic shape depending on the changing shape and position of the low-viscosity bolus and the longitudinal distribution of resistance. The shape and position of the bolus within the lung at a given time were calculated using the change in viscosity of the blood measured as the bolus entered the pulmonary artery and as it emerged from the left atrium. Assuming that the hemodynamic resistance of a small segment of the vasculature is proportional to the product of the viscosity and its geometric factor, we employed a sequential-pattern search technique to calculate the “best” longitudinal distribution of the geometric factor, compatible with the position and dispersion of the bolus at any time and the arterial pressure curve.
Thermoregulatory responses during competitive marathon running
Authors: Maron M. B. , Wagner J. A. , Horvath S. M.
Published: December 2017

Page 909: M. B. Maron, J. A. Wagner, and S. M. Horvath. “Thermoregulatory responses during competitive marathon running.” In three places TR (black globe, radiant temperature) should be substituted for Tre. Page 910: at the bottom of the left-hand column, substitute ... R was calculated from the Stefan-Boltzmann equation

(See PDF)

And in the fourth and fifth lines from the top of the right-hand column, substitute... and Tdb was used as an approximation of TR.... Page 911: in the seventeenth line from the top of the right-hand column, substitute.... The use of Tdb as an approximation of TR should not influence the results greatly....