bluuebunny/crossref_metadata_2025 huggingface dataset:
Tissue oxygenation and splenic erythropoiesis during chronic hypoxia and hypercapnia
Authors: Streeter R. G. , Pepelko W. E. , Cain S. M.
Published: December 2017

Tissue (gas pocket) oxygen levels and erythropoietic activity were monitored in groups of rats chronically exposed to hypoxia (70 Torr PIO2), hypercapnia (60 Torr PICO2), or a combination of the two conditions. Arterial gas tensions and pH were also measured. Overall condition of the animals was assessed by comparison of growth rates with pair-fed controls. Hypoxic-hypercapnic pocket PO2 values (24–40 Torr) were similar to normoxic-normocapnic values (28–37 Torr), but greater than in hypoxia-normocapnia, and less than in normoxia-hypercapnia. Erythropoietic activity during hypoxia-hypercapnia ceased and the rats had a growth rate significantly below that of other groups. While chronic CO2 does increase tissue (pocket) oxygenation to near normal levels, probably due to increased ventilation and subsequently PaO2, the hypoxic-hypercapnic rats evidenced greater detrimental effects than did rats in hypoxic or hypercapnic environments.
Moment analysis of multibreath lung washout
Authors: Saidel G. M. , Salmon R. B. , Chester E. H.
Published: December 2017

A moment analysis of multibreath nitrogen washout has been developed to provide a sensitive, quantitative measure that characterizes the inhomogeneity of pulmonary ventilation. To test the analysis scheme, we studied 5 normal subjects and 16 subjects with obstructive lung disease who performed each washout test at constant tidal volume and frequency. Subjects executed the wahout test 3–4 times at different tidal volumes (0.5–1.5 liters) and frequencies (10–30/min). Plotting washout data as dimensionless end-tidal nitrogen concentration versus the cumulative expired volume normalized by the functional residual capacity (CEV/FRC) renders the washout curves of each individual almost superposab le despite changes in breathing frequency and tidal volume from test to test. The dimensionless washout curve is treated as a distribution from which the normalized first (M1/Mo) and second (M2/Mo) moments are obtained. These parameters clearly display diagnostic clustering for various disease states. With respect to the normal subjects, the magnitude of M1/Mo was 26% greater for asthmatics, 38% greater for bronchitics, and 52% greater for emphysematics. This moment analysis provides an objective, quantitative assessment of the extent of ventilation inhomogeneities without specification of a lung model
A microindentation technique to measure rheological properties of the vascular intima
Authors: Gow B. S. , Vaishnav R. N.
Published: December 2017

A microindentor was developed to measure the depth of indentation of the intimal surface of arterial tissue loaded by flat-ended, cylindrical probes. The depth of indentation depended on the initial stretch of the tissue which required a rigid support (plaster of Paris) beneath the adventitial surface. Probe tips used ranged from 550-mum down to 65-mum diameter while loads ranged from 800 to 15 mg. The depth of indentation was markedly time dependent; that obtained 30 s after loading (variation of 30) was reproducible and served as a useful parameter of viscoelasticity of the aortic intima and supporting tissues of dog and man. The mean variation of 30 (0.19-mm diam tip, 120-mg load), obtained from longitudinal series of indentations of nine dog aortas, ranged from 40.8 to 68.8 mum while coefficient of variation in these series ranged from 4.8 to 15.9%. Intimal pads were found to have greater resistance to identation than adjacent tissue; likewise the tissue on the dorsal, intimal surface of the aorta had lower variation of 30 values compared with the rest of the intima. Lipid-filled intimal regions were about twice as complaint as macroscopically spared areas. The technique should prove useful in understanding the microrheological response of the blood vascular interface to hydrodynamic stresses.
A system to regulate aortic pressure in the rat
Authors: Smith D. M.
Published: December 2017

A servo-controlled aortic clamp has been designed and used for the first time in the anesthetized rat to control femoral arterial pressure. An electrical schematic is given and details of the mechanical clamp used to compress the abdominal aorta are shown. The system has a long-term (30 min) mean pressure control of plus or minus 2 mmHg although some 1–2 s transients of plus or minus 3 mm may occur. It responds to a desired step change in pressure in less than 2 s. The system allows accurate and convenient control of aortic pressure and minimizes the technical difficulties encountered when one attempts similar control by manual means. It therefore facilitates investigation of the effect of transient or steady-state changes in arterial pressure on organ function, e.g., autoregulation of renal blood flow and glomerular filtration rate.
Permanent cannulation of the hepatic portal vein in rats
Authors: Sable-Amplis R. , Abadie D.
Published: December 2017

A technique is described for chronic cannulation of the hepatic portal vein in rats. The T-shaped cannula is made in the laboratory from polyethylene tubing. Implantation of the cannula allows injection or blood withdrawal in a small laboratory animal which is unanesthetized and unrestrained. Simultaneous implantation of intracardotid and intraportal cannulas permits comparisons of blood composition in order to study the role of the liver or intestinal absorption.
Negative arterial-mixed expired PC02 gradient during acute and chronic hypercapnia
Authors: Jennings D. B. , Chen C. C.
Published: December 2017

In resting conscious dogs physiological dead space was calculated using the Bohr equation and measurements of arterial and mixed expired carbon dioxide tension. Whenever dogs inhaled carbon dioxide mixtures (5–10%) that had normal or low oxygen concentrations, the calculated dead space became negative. This paradox was based on the fact that the mixed expired carbon dioxide tension in resting hypercapnic dogs. Under these circumstances carbon dioxide was produced from the lung as measured by gas analyses and blood analyses. By the lung as measured by gas analyses and blood analyses. By reasoning this implies that “alveolar” carbon dioxide tension was higher than pulmonary venous carbon dioxide tension. The negative carbon dioxide gradient persisted at 14 days of chronic hypercapnia and reverted to normal within 10 min of breathing air after chronic hypercapnia. These findings suggest that the exchange of carbon dioxide in the lung cannot be explained solely on the basis of passive diffusion.
Rabbit's ear in cold acclimation studied on the change in ear temperature
Authors: Harada E. , Kanno T.
Published: December 2017

The role of the rabbit's ear in cold acclimation was studied by varying the temperature of a climatic room in the range from -10 to +30 degrees C; The skin temperature in a nonanesthetized rabbit's ear showed a characteristic response to changes in ambient temperatures; plotting the ear temperature against the ambient temperature yielded an S-shaped curve. The mean ambient temperature corresponding to the inflection point on the S-shaped curve shifted significantly from about 13 degrees C to about 8 degrees C after cold acclimated of a group fed for 7 wk at -10 degrees C. The shift of the S-shaped curve after cold acclimation may not be due to the change in the norepinephrine sensitivity of the vascular beds of the ear: the effect of norepinephrine on the pressure-flow curve in the isolated rabbit's ear was almost unchanged between the control and the cold-acclimated groups. It is proposed that the shift of the inflection point gives a qualitative index of the acclimated state of the rabbit at a particular temperature.
Correlation between skeletal calcium mass and muscle mass in man
Authors: Ellis J. K. , Cohn S. H.
Published: December 2017

The measurements of total body potassium (TBK) and calcium (TBCa) were made on 317 subjects by the techniques of whole-body counting and total-body neutron activation analysis (TBNAA), respectively. The TBK/TBCa ratios are constant for normals over the age range studied. The males have more cellular mass (TBK) per unit skeletal mass (TBCa) than the females, as indicated by their respective TBK/TBCa ratios, 0.122 +/- 0.008 (1 SD), and 0.100 +/- 0.007 (1 SD). In general, patients with various metabolic disorders tend to follow the physiological trend found in the normals. In a number of metabolic disorders, the loss of TBK was usually approximately 60% of that of the TBCa when expressed in terms of the predicted normal values. This suggests that the mechanism causing the loss of calcium in physiological and altered metabolic states simultaneously involves both the skeleton and its associated musculature.
Body temperatures during menopausal hot flashes
Authors: Molnar G. W.
Published: December 2017

Body temperatures during hot flashes were measured in a menopausal woman. Internal temperatures fell after each flash; lowest: rectal, 35.6 degrees C; vaginal, 35.6 degrees C; tympanic, 35.2 degrees C. Where sweating occurred, the skin temperature fell during the flash and rose after it. Finger and toe temperatures always showed a sharp rise at the onset of a flash with a slower fall after the flash. Only the cheeks showed additional temperature rises; maximum, 0.7 degrees C. The heart accelerated 13% at the onset of the flash but slowed immediately thereafter. The flash interval was sharply demarcated by undulations in the ECG baseline. There was never any premonitory sign of the imminence of a flash. A central excitatory state seemed to build up, perhaps by the accumulation of a chemical compound, but not of heat, which was explosively dischargedmthe thermal distress was probably evoked by vascular warming in the cheeks. Dabbing the malar prominences with cold water brought prompt relief.
Influence of starvation on the lung: effect on glucose and palmitate utilization
Authors: Rhoades R. A.
Published: December 2017

The relative utilization of [U-14C]glucose and [1–14C]palmitate was examined in lung slices of male Long Evans hooded rats fed ad libitum and starved for 72 h. Food deprivation (72-h fast) significantly decreased [U-14C]flucose oxidation and incorporation into lung lipids. Glucose incorporation into phospholipid-fatty acid (53%) was, in proportion, more markedly reduced than into phospholipid-gluceride glycerol (33%), suggesting that glucose was being conserved for the formation of alpha-glycerol phosphate. (1–14C) palmitate utilization following fasting showed a significant 40% increase in oxidation, and a significant 16% increase in phospholipids, indicating preferential utilization of fatty acids over glucose. Phospholipid fatty acid composition, surface tension measurements and volume-pressure curves were not affected by fasting. Khe data indicate that glucose and palmitate metabolism are interrelated, and that the relative utilization of these substrates is changed to maintain essential lung lipids during an altered physiologic state.
A simple method to improve the precision and accuracy of gas-phase oxygen electrodes
Authors: Wennberg I. A.
Published: December 2017

The precision and accuracy of the measurements using an oxygen gas-phase electrode thermostabilized in an ice bath were evaluated. The precision found was comparable with that obtained with the paramagnetic method and with Scholander analysis. The accuracy was comparable with that of the paramagnetic method.
Lung oxygen consumption and mitochondria of alveolar epithelial and endothelial cells
Authors: Massaro G. D. , Gail D. B. , Massaro D.
Published: December 2017

We examined oxygen consumption by lung slices and measured the volume density of mitochondria of granular pneumocytes, alveolar type I cells, and alveolar capillary endothelial cells in several species. We found that lung oxygen consumption (mu-1 02 times h-1 times mg DNA-1) varies inversely with the log of animal body weight and with the species alveolar diameter and directly with the species respiratory rate. The volume density of granular pneumocyte mitochondria show a direct linear correlation with the lung's oxygen consumption and the species respiratory rate, and an inverse linear correlation with the species alveolar diameter. The volume density of mitochondria in type I alveolar epithelial cells and capillary endothelial cells, considered together, did not differ in the two species studied (mouse and rat). We conclude that there are interspecies differences in oxygen consumption by lung cells and that granular pneumocytes contribute to these differences. We suggest that, at least part of these differences, are related to interspecies differences in surfactant secretory activity.
Effect of ambient temperature on heat production and heat loss in burn patients
Authors: Wilmore D. W. , Mason A. D. , Johnson D. W. , Pruitt B. A.
Published: December 2017

Four controls and eight burned patients with thermal injury ranging from 7 to 84% total body surface were studied in an environmental chamber at 25 and 33 degrees C ambient temperature and a constant vapor pressure during two consecutive 24-h periods. Hypermetabolism was present in the burn patients in both ambient temperatures and core and skin temperatures were consistently higher than in the normal men despite increased evaporative water loss. The higher environmental temperature decreased metabolic rate in patients with large thermal injuries in whom the decrement in dry heat loss produced by higher ambient temperature exceeded the increase of wet heat loss. In patients with burns smaller than 60%, these changes equaled one another and higher environmental temperature exerted no effect on metabolic rate. Core-skin heat conductivity increased with burn size; patients with large burns were characterized by inadequate core-skin insulation when exposed to the cooler environment, necessitating the compensatory increase of metabolic rate. This increase, however, was small and of the order of 5–8 kcal times m-2 times h-1.
Hormonal and electrolyte response to exposure to 17,500 ft
Authors: Frayser R. , Rennie I. D. , Gray G. W. , Houston C. S.
Published: December 2017

Hormone, electrolyte, and body fluid compartment changes were studied in subjects who either spent time at 10,000 ft before flying to 17,500 ft or were premedicated with acetazolamide and flown directly to 17,500 ft. In the former group, at 10,000 ft, renin and aldosterone were not different from control. Cortisol increased significantly from 9.8 to 19.5 mug/100 ml on the third day. At 17,500 ft, renin, aldosterone and cortisol were significantly elevated on day 3 but had returned to control levels by day 5. Sodium and potassium excretion was significantly reduced at both altitudes. Total body water, extracellular and plasma volume were reduced (P less than 0.05) at 17,500 ft. Subjects pretreated with acetazolamide and flown directly to 17,500 ft had significant increases (P less than 0.001) in plasma renin, aldosterone, and cortisol levels during the first 4 days at altitude. On day 1 there was a decrease of 45% in sodium and 38% in potassium excretion. On day 4 there was a decrease of 63% and 51%, respectively. These changes are not associated with the premedication. The initial changes may reflect the immediate response to stress and alkalosis followed by a return to control levels as the body adapts to altitude.
Blood flow during 2-Torr exposures at different decompression rates
Authors: Cooke J. P. , Olson R. M.
Published: December 2017

Central and peripheral blood flow of denitrogenated dogs, measured in the femoral artery and aorta, declined rapidly and ceased within mean times of 28, 35, 70, or 90 s after 1-, 10-, 30-, or 60-s decompressions from 258 Torr to 2 Torr, respectively. Neither arterial nor venous hypoxemia was seen after 1-s decompressions since the hypoxic blood did not reach the aorta. In contrast, arterial and venous O2 saturation levels dropped as low as 12 or 6% following 10- to 60-s decompressions since circulation continued. A severe and transient decerebratelike rigidity and subsequent temporary flaccid paralysis of the hind legs was seen during recovery from decompressions slower than 1 s, whereas only a mild temporary flaccid paralysis was frequently present after 1-s decompression. The more severe responses following 10- to 60-s decompressions are associated with the greater hypoxemia after slow decompressions, indicating tissue hypoxia is more severe when decompression rate is slow.
Static pulmonary compliance in ponies
Authors: Rawlings C. A. , Birnbaum M. L. , Bisgard G. E.
Published: December 2017

Static pulmonary and total compliance during expiration was measured in fifteen healthy anesthetized ponies. Mean body weight of the ponies was 140.6 kg and ranged from 83.6 to 211.4 kg. For the fifteen ponies, mean values and SD were: total compliance (Ct), 168.7 plus or minus 47.2 ml/CMH2O, and mean pulmonary compliance (Cl), 368.4 plus or minus 90.3 ml/cmH2O. Both Ct and Cl were significantly dependent on body weight, calculated surface area, height at the withers, and circumference about the chest. Repeatability of compliance measurement from day to day was confirmed by measuring compliance on consecutive days in four ponies.
Time course of exchanges between red cells and extracellular fluid during CO2 uptake
Authors: Forster R. E. , Crandall E. D.
Published: December 2017

A stopped-flow rapid-reaction apparatus was used to follow the time course of extracellular pH in a human red cell suspension following a sudden increase in PCO2. The extracellular pH change was slow (t1/2 similar to 3.5 s) considering the presence of carbonic anhydrase in the cells. When carbonic anhydrase was added to the extracellular fluid, the half-time was reduced to less than 20 ms. The explanation for these phenomena is that the equilibration of H+ across the red cell membrane is rate-limited by the uncatalyzed reaction CO2 plus H2O formed from H2CO3 outside the cells. A theoretical model was developed which successfully reproduced the experimental results. When the model was used to simulate CO2 exchange in vivo, it was determined that blood PCO2 and pH require long times (greater than 50 s) to approach equilibrium between cells and plasma after leaving an exchange capillary. We conclude that cell-plasma equilibrium may never be reached in vivo, and that in vitro measurements of these quantities may not represent their true values at the site of sampling.
Prediction of survival time of rats in severe heat
Authors: Ohara K. , Furuyama F. , Isobe Y.
Published: December 2017

The response pattern of the rectal temperature of unanesthetized rats exposed to an acute heat in a room of 42.5 degrees C, rh 40% was analyzed in relation to survival time (S), equilibrium rectal temperature (Te), rise in Te from the initial temperature (Delta Te), and the slope of the changes in rectal temperature during the equilibrium period (Gt). A very wide fluctuation of the survival time (from 46.8 to 250.0 min) was observed between individual rats. For prediction of the survival time, following formula was obtained: log(S) = K1 - K2 times log (Te) - K3 times log (Delta Te) + k4 times 10- minus Gt. K1–4 are constants which differ according to sex. The predicted survival time showed highly constant results in individual rats when measured by repeated exposures. The predicted time coincided well with the survival time actually measured, the difference between the two (measured minus predicted) being 2.2 plus or minus 21.7 min (mean plus or minus SD) IN 77 RATS. There was also a significant correlation between the survival time predicted for acute heat exposure and the actual survival time of individual rats when they were exposed to a chronic heat by daily elevation of the rearing room temperature by 1.0 degrees C.
Chronic cannulation for intermittent intravenous fluid administration
Authors: Mostardi R. A. , Worsencroft D. , Stern J. , Vanessen F.
Published: December 2017

A system is described for rapid and effective venous cannulation for long-term administration of fluids in rabbits. This method is completely free of any harness or sling-type apparatus and in no way interferes with the normal mobility of the animal. The animals maintained in this way have participated in programs of tri-weekly administration (2–3 ml/dose) of fluid for as long as 5 mo.
Effects of previous exercise with arms or legs on metabolism and performance in exhaustive exercise
Authors: Karlsson J. , Bonde-Petersen F. , Henriksson J. , Knuttgen H. G.
Published: December 2017

The ability of additional muscles to perform after certain other muscles of the body had been exercised to exhaustion was studied in three male subjects. Exhaustive exercise was performed in two series: series L-A, a bout of leg exercise preceded a bout of arm exercise; series A-L, arm preceded leg (6-min recovery between bouts). Biopsies were taken during the course of each experiment from both the deltoideus and vastus lateralis muscles for determination of ATP, creatine phosphate, lactate, and pyruvate. Exhaustive exercise led to marked elevations in lactate and decreases in ATP and CP in exercised muscle and marked increases in blood lactate concentration. Similar changes, especially in lactate, were observed during and after the first exercise bout in nonexercised muscle. When arm or leg exercise was performed as the second bout, decreases in performance time were observed as compared to performance as the initial bout. It is suggested that the performance potential of muscle is decreased because of internal changes elicited by elevated blood lactate and/or blood H+ concentrations brought about by other muscle groups previously exercised to exhaustion.
Effects of hypoxia and histamine infusion on lung blood volume
Authors: Dawson C. A. , Forrester T. E. , Hamilton L. H.
Published: December 2017

Using an isolated perfused cat lung preparation we examined the effects of hypoxia and histamine infusion on the lung blood volume. Total lung blood volume was determined from the indocyanine green transit time and the ether bolus technique was used to estimate arterial and venous volumes during forward and retrograde perfusion, respectively. Changes in lung total fluid content were determined from changes in the blood volume of the perfusion system. Hypoxia increased perfusion pressure and decreased total fluid and blood volume. Histamine infusion also increased perfusion pressure and decreased blood volume. However, histamine increased total fluid volume, indicating an increase in vascular permeability. Hypoxia decreased arterial and venous volumes, and histamine decreased venous volume. The slopes of the arterial and venous volume/pressure curves were not altered by hypoxia or histamine.
Atropine modification of the pulmonary effects of chemical mediators in the guinea pig
Authors: Drazen J. M. , Austen K. F.
Published: December 2017

The actions of histamine, slow-reacting substance of anaphylaxis (SRS-A), Bradykinin, and prostaglandin F2alpha on pulmonary mechanics in the unanesthetized guinea pig were separated into direct and secondary cholinergic airway effects on the basis of alteration of their actions by atropine. The effects of SRS-A (500 and 3,000 units/kg) on compliance were not significantly altered by atropine, while the effects of bradykinin (3.0 and 30 mug/kg) on compliance were decreased only at 3.0 mug/kg by atropine. The effects of both of these agents on resistance were decreased by atropine, suggesting that SRS-A and bradykinin act directly on the peripheral airways and by secondary cholinergic mechanisms on both central and peripheral airways. The effects of histamine (3.0 mug/kg) on both compliance and resistance were abolished by atropine, suggesting an action mainly via cholinergic pathways; while at a higher dose, 9.0 mug/kg, there was both a direct and a cholinergic action. The effects observed 20 sec after the administration of prostaglandin F2alpha (PGF2alpha) were not altered by atropine suggesting a direct action on airways, while both the compliance and resistance changes observed 3–8 min after PGF2alpha were abolished by atropine suggesting that the latter effects were mediated solely by cholinergic mechanisms.
Blunted hypoxic pulmonary vasoconstriction by increased lung vascular pressures
Authors: Benumof J. L. , Wahrenbrock E. A.
Published: December 2017

We tested the hypothesis that increased pressures within the lung vessels would inhibit hypoxic pulmonary vasoconstriction at all levels of alveolar CO2 tension. Selective hypoxia of the left lower lobe of the lung in open chested dogs caused the electromagnetically measured blood flow to the lobe to decrease 51 plus or minus 4 (SE) percent and its vascular resistance to increase 132 plus or minus 13 percent. Pressure and blood flow in the main pulmonary artery and left atrial pressure did not change during the hypoxic response. Stepwise increments in left artrial and pulmonary arterial pressures induced either by inflating a left atrial balloon or infusing dextran, progressively diminished the vasoconstrictive response to hypoxia. The response was usually abolished when left atrial pressure reached 25 mmHg. For all vascular pressures, hypoxic vasoconstriction was blunted by hypocapnic alkalosis but not enhanced by hypercapnia. We conclude that the redistribution of blood flow away from an hypoxic lobe of the lung to lobes with high Po2 was greatly attenuated by increasing pressures within lung vessels or by inducing respiratory alkalosis.
Comparison of physiological responses of women and men to isometric exercise
Authors: Petrofsky J. S. , Burse R. L. , Lind A. R.
Published: December 2017

The volunteers for this study were 83 women, aged 19–65 yr, drawn from several different occupations. Three minutes after exerting maximal handgrip strength (MVC) each subject held a tension of 40 percent MVC to fatigue. Blood pressures and heart rates were measured before, during, and after the endurance of contraction. Age was associated with a reduction of strength of the women, whereas their endurance at 40 percent at 40 per cent MVC increased. There was evidence that menopause enhanced those age effects for strength and endurance. At rest, age was associated with a decreased heart rate. As expected, the heart rates of all the women increased during the endurance contraction. But that increase was greater for the younger than for the older women, thereby exaggerating the difference due to age already seen at rest. Systolic blood pressure at rest was higher with age and, in a similar manner, that relationship was also exaggerated throughout the isometric contraction. Diastolic blood pressure, however, was not changed with age at rest, and although the diastolic pressure increased during the isometric exercise, the rate of increase was unaffected by age. The results obtained are compared with those from a similarly large number of men examined in identical circumstances.
A simple module for on-line computation of stroke volume and cardiac output
Authors: Pinardi G. , Sainz A. , Santiago E.
Published: December 2017

An easily constructed, low-priced, simple, and reliable module to obtain stroke volume and cardiac output by analog integration of aortic blood flow velocity signals is described. Rapid data analysis of physiologic and pharmacologic cardiovascular responses in dogs is greatly facilitated by on line computation of these parameters.
Preparation for repeated study of left ventricular function in the conscious dog
Authors: Beazell J. , Garner D. , Laks M. M.
Published: December 2017

A method is presented for a relatively simple nontraumatic chronic left heart catheter preparation for the study of left ventricular hemodynamics in the conscious dog. In 30 dogs an 8 Fr Cordis catheter was modified and implanted into the left ventricle via the right atrial septum. Transseptal catheterization was performed without significant morbidity and mortality. Left ventricular cineangiograms and pressures and cardiac outputs have been repeatedly performed on fully conscious dogs with no apparent discomfort displayed by the dog.
Cerebral hemodynamics following internal maxillary artery ligation in the goat
Authors: Miletich D. J. , Ivankovic A. D. , Albrecht R. F. , Toyooka E. T.
Published: December 2017

Changes in cerebral and extracerebral blood flow in the goat after ligation of the internal maxillary artery and deliberate thrombosis of the extracerebral arteries (buccinator, ethmoidal, and ophthalmic) with thrombin were compared to changes seen in animals after internal maxillary artery ligation only and in normal animals where no surgical manipulations were performed. Blood flow was measured by injecting 51-Cr-labeled microspheres into the internal maxillary artery via a catheter placed into the temporal artery. Analysis of the radioactivity in extracerebral and intracerebral tissues indicated that when the internal maxillary artery is ligated and the extracerebral arteries are thrombosed, virtually all of the blood flow from the carotid artery is destined from the brain. However, if only the internal maxillary artery is ligated nearly one-fourth of the blood flow from the maxillary travels to extra-cerebral tissues. In normal animals, it was determined that only one-fourth of the blood flow in the internal maxillary is destined for the cerebral circulation. Results from this study indicate that if the former method is employed an accurate measure of cerebral blood flow is possible without the complications of extra-cerebral flow. If the latter technique is used care must be taken in evaluating cerebral blood flow since a large component of extra-cerebral blood flow is present.
Suppression of ADH during water immersion in normal man
Authors: Epstein M. , Pins D. S. , Miller M.
Published: December 2017

Since previous studies from this laboratory have demonstrated that the redistribution of blood volume and concomitant relative central hypervolemia induced by water immersion to the neck causes a profound natriuresis and a suppression of the renin-aldosterone system, it was of interest to assess whether the diuresis induced by immersion was mediated by an analogous inhibition of ADH. The effects of water immersion on renal water handling and urinary ADH excretion were assessed in 10 normal male subjects studied following 14 h of overnight dehydration on two occasions, control and immersion. The conditions of seated posture and time of day were identical. During control ADH persisted at or above prestudy values. Immersion resulted in a progressive decrease in ADH excretion from 80.1 plus or minus 7 (SEM) to 37.3 plus or minus 6.3 muU/min (P smaller than 0.025). Cessation of immersion was associated with a marked increase in ADH from 37.3 +/- 6.3 muU/min to 176.6 +/- 72.6 muU/min during the recovery hour (P smaller than 0.05). Concomitant with these changes urine osmolality decreased significantly beginning as early as the initial hour of immersion from 1044 +/- 36 to 542 +/- 66 mosmol/kg H2O during the final hour of immersion (P smaller than 0.001). Recovery was associated with a significant mean increase in Uosm of 190 +/- 40 mosmol/kg H2O over the final hour of immersion (P smaller than 0.001). The suppression of ADH occurred without concomitant changes in plasma tonicity. These studies are consistent with the suggestion that in hydrated subjects undergoing immersion suppression of ADH release contributes to the enhanced free water clearance, which has been previously documented.
Nitrogen and bolus closing volumes: differences after histamine-induced bronchoconstriction
Authors: Benson M. K. , Newberg L. A. , Jones J. G.
Published: December 2017

Studies in normal subjects have shown that there is little difference in the size of the closing volume when measured by either the nitrogen methods or a bolus method. In this study we have examined the changes in closing volume following histamine-induced bronchoconstriction. In five normal subjects histamine resulted in a reduction in the vital capacity, an increase in the residual volume, and an increase in the airway resistance. The size of the closing volume measured by a bolus method increased after induced bronchoconstriction (0.52 +/- 0.15 1 to 0.74 +/- 0.17 1). With the nitrogen method the closing volume became smaller (0.51 +/- 0.19 1 to 0.17 +/- 0.17 1). Similar differences between the two methods are demonstrated in patients with asthma. The suggested explanation for these differences lies in the different methods used to establish a concentration gradient of gas in the lung. If there is “air trapping” the nitrogen method may fail to establish a concentration gradient.
Distribution of ventilation-perfusion ratios in dogs with normal and abnormal lungs
Authors: Wagner P. D. , Laravuso R. B. , Goldzimmer E. , Naumann P. F. , West J. B.
Published: December 2017

We have recently described a new method for measuring distributions of ventilation-perfusion ratios (VA/Q) based on inert gas elimination. Here we report the initial application of the method in normal dogs and in dogs with pulmonary embolism, pulmonary edema, and pneumonia. Characteristic distributions appropriate to the known effects of each lesion were observed. Comparison with traditional indices of gas exchange revealed that the arterial PO2 calculated from the distributions agreed well with measured values, as did the shunts indicated by the method and by the arterial PO2 while breathing 100 per cent 02. Also the Bohr dead space closely matched the dispersion of ventilation in realtion to VA/Q. Assumptions made in the method were critically evaluated and appear justified. These include the existence of a steady state of gas exchange, an alveolar-end-capillary diffusion equilibration, and the fact that all of the observered VA/Q inequality occurs between gas exchange units in parallel. However, theoretical analysis suggests that the method can detect failure of diffusion equilbration across the blood-gas barrier should it exist. These results suggest that the method is well-suited to clinical investigation of patients with pulmonary disease.
Demonstration of airway closure in man
Authors: Engel L. A. , Grassino A. , Anthonisen N. R.
Published: December 2017

After partial equilibration of the lung with a N2O gas mixture absorption of N2O by the pulmonary circulation results in a flow of gas into the lungs during breath holding. A bolus of 133Xe introduced at the mouth at the beginning of the breath hold is carried in by the gas flow and distributed according to regional perfusion. In three subjects, breath holding at FRC, apex-to-base distribution of a 133Xe bolud delivered by N2O absorption (Xecar) was similar to that of a bolus injected intravenously (Xeiv). Near RV however, much less of Xecar penetrated into dependent zones than expected from the distribution of Xeiv. In fact, distribution of Xecar did not differ from that of a slowly inhaled bolus. Correction for Compton scatter in the chest wall, measured in one subject, accounted only in part for the radioactivity recorded over dependent lung regions. The findings indicate that near RV some but not all of the dependent airways must be closed. Furthermore, the distribution of airway closure completely accounts for the distribution of a bolus inhaled from RV.
A blood pressure-regulating device for inducing hemorrhagic shock
Authors: Culpepper R. D. , Culpepper R. L. , Turner M. D.
Published: December 2017

An instrument for producing closely controlled and repeatable hemorrhagic shock in laboratory animals is described. A Sarns roller pump, controlled by an electronic device, is used to pump blood in and out of the animal at a constant rate. Photoelectric cells are used to sense pressure changes and depending on their configuration, the pump runs forward or backward or stops. Pressures are accurately maintained, bleeding and reinfusion rates are controlled, and a record of bleeding patterns is provided.
Effect of altered G levels on deposition of particulates in the human respiratory tract
Authors: Hoffman R. A. , Billingham J.
Published: December 2017

The primary mode of depositon of particles in the respiratory tract in the size range 0.5–10 mum diam (unit density) is sedimentation. The rate of sedimentation is directly proportional to the velocity of settling of the particle. Therefore, the total deposition of particles in the respiratory tract as well as the region of deposition is affected by changes in gravity. Human subjects were exposed to aerosols of 2.02-mum-diam polyvinyltoluene particles at 0, 0.5, 1.0, and 2.0 G. Total deposition was measured at each G level. Results indicate an almost linear increase in total deposition with increasing G levels over the range studied. The deposition measured at 1 G was less than reported in earlier experiments and the deposition at levels less than 1 G was less than had been calculated by Muir and Beeckmans. These data show that although sedimentation plays the major role in depostion of 2.02 mum particles, it is less than previously described.
Synergistic relationship of temperature, air, velocity, and mercury in the chicken
Authors: Thaxton P. , Yonushonis W. P. , Baughman G. R.
Published: December 2017

Juvenile chickens that had previously received mercuric chloride intramuscularly were subjected to an acute exposure of high ambient temperature in the presence or absence of a 140 mpm air velocity. This level of mercury did not retard growth of affect the resting body temperature. However, following heating the birds experienced a greater hyperthermia than similarly heated controls and consequently thermal death occurred earlier. When a high air velocity was maintained during heating the hyperthermic condition was further amplified, as was the event of thermal death. It is concluded that a synergistic relationship exists between mercury, when administered at a nontoxic level, and the climatic factors of temperature and air velocity.
Mean myoglobin oxygen tension during exercise at maximal oxygen uptake
Authors: Clark B. J. , Coburn R. F.
Published: December 2017

Changes in intracellular Po2 in myoglobin containing skeletal muscle during exercise were estimated in normal nonathlete subjects from measurements of shifts of CO between blood and muscle under conditions where the total body CO stores remained constant. Exercise was performed on a bicycle ergometer. In 1.5–2 and 6–7 min runs at Vo2 max with the subject breathing 21% O2, mean MbCO/HbCO increased 146 +/- 7 and 163 +/- 11% of resting values, respectively (P less than 0.05). With the subjects breathing 13–14% O2, in 1.5–2 and 6–7 min runs, Vo2 max fell an average of 4.3 +/- 5.1% and 12.0 +/- 5.2%, respectively, and mean MbCO/HbCO increased to 233 +/- 18% and 210 +/- 52% of resting value, respectively (P less than 0.05). These findings suggest that mean myoglobin Po2 fell during exercise at Vo2 max, with the subjects breathing 21% O2 and the decrease in mean myoglobin Po2 was greater with the subject breathing 13–14% O2. There was considerable variability in different subjects and in some, the data were not consistent with intracellular O2 availability limiting aerobic metabolism. The data support a postulate that there are several limiting factors for the aerobic capacity, including intracellular O2 availability.
Estimation of body fat in rats by whole-body counting
Authors: Pommer A. M. , Lakshmanan F. L.
Published: December 2017

A method for determining body fat in vivo in rats by whole-body counting of 40K is described. The technique utilizes a Nuclear Chicago Corporation TOBOR system with 5-in thallium-activated sodium iodide crystals. To test the method a regression equation was developed using the 40K counts and body weight of young adult rats weighing 333–788 g; the results were compared with those obtained from the gravimetric determination of fat in the carcass. The correlation coefficient between the two methods was 0.945.
Continuous spectrophotometric measurements of arteriovenous oxygen difference
Authors: Shepherd A. P. , Sutherland J. C. , Wilson A. F.
Published: December 2017

A relatively inexpensive dual-beam optical absorbance monitor was tested and adapted to measure arterio-enous oxygen difference ((a - v)delta O2). Since the molar extinction coefficients of oxy- and deoxyhemoglobin are markedly different at 660 nm, the difference in optical density between arterial and venous blood, as measured by the absorbance monitor, was shown to be linearly related to (a - v)delta02. When appropriate cuvettes (optical path length = 0.5 mm) were used, the instrument's 90% response time (4.4 s) was sufficiently rapid for most physiological applications such as Fick determinations of the rate of an organ's oxygen consumption. The theoretical basis of this spectrophotometric (a - v)deltaO2 measurement and sources of error are discussed in detail.
An in vitro inhibitor of Na-K-ATPase present in an adenosinetriphosphate preparation
Authors: Charney A. N. , Silva P. , Epstein F. H.
Published: December 2017

An in vitro inhibitor of Na-K-ATPase was discovered in a commonly used preparation of ATP made by the Sigma Chemical Company, St. Louis, Mo. (Sigma grade ATP). As measured by a reliable and widely used assay system in which phosphate liberation in measured colorimetrically, Na-K-ATPase activity in the rat kidney, small intestine and colon was about 50% lower then Sigma grade ATP was used as substrate as compared to another Sigma Chemical Company product II ATP. Mg-ATPase and adenylate cyclase assays were unaffected by substituting Sigma grade for grade II ATP. The inhibitor of Na-K-ATPase could not be identified. Sigma grade ATP probably should not be used when measuring the activity of Na-K-ATPase in the rat kidney, small intestine, or colon.
Lung water volume at rest and exercise in dogs
Authors: Marshall B. E. , Soma L. R. , Neufeld G. R.
Published: December 2017

Lung water volume was measured in dogs killed at rest and during maximal exercise. There was no significant difference between them. It is concluded that pulmonary interstitial edema does not occur during exercise.
Prediction of body composition in habitually active middle-aged men
Authors: Lewis S. , Haskell W. L. , Klein H. , Halpern J. , Wood P. D.
Published: December 2017

In 45 physically active men (ages 35–67 yr) who underwent hydrostatic weighing to determine body composition, multiple regression equations were developed for the prediction of body density (D), lean body weight (LBW), fat body weight (FBW), and % fat using selected anthropometric measurements. The prediction accuracy for these parameters using several previously generated anthropometric regression equations was also determined. With equations developed from the present data a substantially higher correlation was obtained between measured and predicted LBW (r = 0.95) than between measured and predicted D (r = 0.85), FBW (r = 0.88), or % fat (r = 0.84). When previously developed equations were applied to the present sample, correlations between measured and predicted values were considerably lower (4–42%) than in the original studies; this reduction was least in the case of LBW. Analysis of previous data indicated that in selected populations total body weight can account for a relatively large fraction of the variance in LBW. LBW may be estimated quite accurately (r greater than or equal to 0.90) in physically active men with one of several regression equations which include total body weight as an independent variable.
Effects of equivalent sea-level and altitude training on VO2max and running performance
Authors: Adams W. C. , Bernauer E. M. , Dill D. B. , Bomar J. B.
Published: December 2017

Twelve middle-distance runners, each having recently completed a competitive track season, were divided into two groups matched for maximal oxygen uptake (VO2max), 2-mile run time and age. Group 1 trained for 3 wk at Davis, PB = 760 mmHg, running 19.3 km/day at 75% of sea-level (SL) VO2max, while group 2 trained an equivalent distance at the same relative intensity at the US Air Force Academy (AFA), PB = 586 mmHg. The groups then exchanged sites and followed a training program of similar intensity to the group preceding it for an additional 3 wk. Periodic near exhaustive VO2max treadmill tests and 2-mile competitive time trials were completed. Initial 2-mile times at the AFA were 7.2% slower than SL control. Both groups demonstrated improved performance in the second trial at the AFA (chi = 2.0%), but mean postaltitude performance was unchanged from SL control. VO2max at the AFA was reduced initially 17.4% from SL control, but increased 2.6% after 20 days. However, postaltitude VO2max was 2.8% below SL control. It is concluded that there is no potentiating effect of hard endurance training at 2,300-m over equivalently severe SL training on SL VO2max or 2-mile performance time in already well conditioned middle-distance runners.
Effects of hyperoxic gas mixtures on energy metabolism during prolonged work
Authors: Wilson B. A. , Welch H. G. , Liles J. N.
Published: December 2017

These experiments were designed to study selected respiratory and metabolic responses to exercise in hyperoxia. Four subjects were examined during 30-min bicycle ergometer rides at both 40% and 80% of their aerobic maximum. The VO2 was significantly increased at both work levels breathing 60% O2 versus 21% O2, while VCO2 showed no significant change during the 40% exercise tests but was significantly decreased during the 80% intensity rides. The average increase in the volume of O2 taken up during 30 min of hyperoxic exercise, compared with normoxia, was 3.3 liters at the 40% exercise level and 5.6 liters at the 80% level. Neither the magnitude of the O2 nor the CO2 storage calculated for the exercise bouts could explain these increases. Steady-state criteria for the gas stores were established by the stable values of PETCO2, VO2, VCO2, and VI from minute 6 through 30 at both work levels. R values decreased during the hyperoxic tests suggesting the possibility of a shift toward increased fatty acid metabolism.
Cardiac norepinephrine stores and chronotropic reflex response after thoracotomy
Authors: Schelbert H. R. , Pavelec R. S. , Sandoval S. , Covell J. W.
Published: December 2017

Although alterations in cardiac reflex activity, as well as in cardiac norepinephrine stores, have been shown following thoracic operations, the physiological relationship between these alterations has not been investigated. Cardiac norepinephrine stores were examined in 17 normal dogs, and in 16 dogs 1–6 wk after a right thoracotomy. The heart rate response to induced arterial hypotension (mean decrease 17–20 mmHg) prior to and following surgery was also examined in 10 dogs. A significant depression in right atrial norepinephrine stores from normal levels of 1.95 +/- 0.13 mug/g to 1.30 +/- 0.25 mug/g (33%) (P less than 0.05) was observed during the first wk following surgery. During the same period the heart rate response to a fall of 17–20 mmHg systolic arterial pressure was clearly reduced from 52.8 +/- 6.9 beats/min to 17.0 +/- 4.8 beats/min (67.8%; P less than 0.05). Right atrial norepinephrine stores at the time of the initial operation and when reflex responses were most markedly depressed demonstrated that the decrease in norepinephrine stores was paralleled by attenuation of the chronotropic response to hypotension.