bluuebunny/crossref_metadata_2025 huggingface dataset:
A method of recording from single muscle fibers or motor units in human skeletal muscle
Authors: Pierce Donald S. , Wagman Irving H.
Published: December 2017

It is possible to record single muscle fiber and single motor unit potentials with a tungsten microelectrode inserted percutaneously (without discomfort) into human muscle. Potentials averaging 10–12 mv, 2–4 msec in duration, have been recorded from such muscles as the gastrocnemius and pectoralis major. Firing of the motor units can be followed almost to a maximum isometric contraction without the action potentials being lost in a mass of other motor unit potentials. A technique has also been developed whereby the position of a microelectrode in a human muscle during isometric contraction can be controlled by means of a micromanipulator. The possibility of inserting hard metal microelectrodes into human skeletal muscle percutaneously and positioning them with a micromanipulator substantially widens the range of the experimental work that can be carried on to elucidate the electrophysiological phenomena concerned in human skeletal muscle contraction.

intramuscular tungsten microelectrode; isotonic and isometric contraction measurement

Submitted on August 2, 1963
Relationship of pulmonary arterial and venous pressure to diffusing capacity
Authors: Lawson W. H. , Duke Helen N. , Hyde Richard W. , Forster Robert E.
Published: December 2017

Single-breath carbon monoxide diffusing capacity (DlCO) was determined in ten isolated perfused cat lungs at 37 C during a) forward (arterial) perfusion through the pulmonary artery and b) reverse (venous) perfusion through the left atrium. Blood flow, inflow and outflow pressure, lung volume, and transpulmonary ventilating pressure were approximately equal in a and b, but in all ten lungs DlCO was greater in b than a. In five lungs during forward (arterial) perfusion blood flow was increased from a mean of 62–180 ml/min while left atrial outflow pressure was maintained about zero mm Hg. At the higher blood flow DlCO was not significantly changed although vascular resistance decreased a mean of 34% and arterial pressure increased a mean of 98%. We conclude that a) transmural pressure in the pulmonary veins is more important than that in the arteries in determining the size of the capillary bed as measured by DlCO, and b) the size of the capillary bed and total vascular resistance can vary independently. When pulmonary edema occurred in five lungs DlCO did not change significantly.

pulmonary capillary bed size; pulmonary edema and lung diffusing capacity; pulmonary blood flow and lung diffusing capacity

Submitted on February 11, 1963
Location and mechanism of airway constriction after barium sulfate microembolism
Authors: Nadel J. A. , Colebatch H. J. H. , Olsen C. R.
Published: December 2017

Injection of barium sulfate microemboli into the right side of the heart of paralyzed, artificially ventilated cats increased pulmonary resistance, decreased pulmonary compliance and functional residual capacity, and increased end-expiratory transpulmonary pressure and anatomic dead space. These effects could be due to constriction of terminal respiratory units without significant narrowing of the large airways, which may actually enlarge. Anatomic studies, performed after rapid freezing of the lungs in the open thorax, showed that the principal site of constriction was the alveolar ducts. Intravenous isoproterenol partially or completely prevented the changes following microembolism, suggesting that they were due to smooth muscle contraction. Vagotomy, injection of heparin or atropine or guanethedine, or inhalation of 6% carbon dioxide did not prevent the changes; prior injections of 48/80 decreased the changes. These studies suggest that the embolism-induced changes depend on histamine release. The varied manifestations of barium sulfate microembolism, including the shift of ventilation to the unaffected areas, atelectasis of embolized areas, anoxemia, and abnormal breathing pattern may depend on the presence and extent of contraction of peripheral respiratory units induced by liberation of histamine.

terminal airway constriction; histamine release; lung compliance; pulmonary resistance; airway anatomy; alveolar duct; muscle

Submitted on August 30, 1963
Factors affecting regional distribution of ventilation and perfusion in the lung
Authors: Bryan A. C. , Bentivoglio L. G. , Beerel F. , MacLeish H. , Zidulka A. , Bates D. V.
Published: December 2017

Regional distribution of ventilation and perfusion in the lung has been studied using Xe133 in normal subjects. In 31 subjects seated upright at rest the previous findings of a gradient of ventilation and perfusion distribution from apex to base of the lung, have been confirmed. The results agree well with those obtained using C15O2. In seven normal subjects lying supine, the V/Q distribution from apex to base of the lung is much more uniform, though a perfusion gradient can be shown to exist from front to back. Five normal subjects exercising on a bicycle ergometer in the upright posture were found to have a proportionately much greater blood flow through the upper zone of the lung than when in the same position at rest. One study during induced syncope on standing indicated that this state is accompanied by a progressive decrease in perfusion to the upper zones of the lung. No change in distribution occurred breathing 100% oxygen.

xenon 133; posture; exercise; syncope; oxygen

Submitted on August 30, 1963
Pulmonary gas exchange during induction of pulmonary edema in anesthetized dogs
Authors: Said Sami I. , Longacher Joseph W. , Davis Ronald K. , Banerjee Chandra M. , Davis William M. , Wooddell W. Jeff
Published: December 2017

We examined pulmonary gas exchange in 19 anesthetized dogs during the induction of acute pulmonary edema by intravenous infusion of dextran in saline. We monitored pulmonary capillary pressure by a left atrial catheter, and arterial blood Po2 by an indwelling electrode. PaOO2 remained near normal until just before pulmonary edema was grossly apparent, when it fell precipitously; left atrial pressure mounted to a peak and then declined. The apparent “steady-state” DlCO was reduced as much as 61%, but the dominant cause of hypoxemia was an increased venous admixture (shunt flow) on O2 breathing. Since the shunt was reversible by forcible inflation of the lungs, induced pulmonary edema was probably associated with closure of alveolar units.

pulmonary venous admixture (shunt flow) and diffusing capacity; alveolar closure; arterial blood oxygen; tension in vivo; hypoxemia

Submitted on August 14, 1963
Cardiac output in muscular exercise at 5,800 m (19,000 ft)
Authors: Pugh L. G. C. E.
Published: December 2017

Cardiac output during muscular exercise was estimated by the acetylene technique on four members of the Himalayan Scientific and Mountaineering expedition 1960–1961 at sea level and 5,800 m (19,000 ft). The output for a given work intensity at 5,800 m (19,000 ft) was comparable with the output at the same work intensity at sea level, but the maximum output was reduced, the mean value being 16 liters/min, compared with 23 liters/min at sea level. Heart rates during light and moderate exercise were higher than the rates observed at the same work intensity at sea level. The maximum heart rate during exercise was limited to 130–150 beats/min compared with 180–196 beats/min at sea level. The stroke volume at altitude was lower than at sea level at each work rate. On breathing oxygen at sea-level pressure, heart rate for a given work intensity was reduced; but the maximum heart rate increased. Indirect evidence suggested that maximum cardiac output increased but probably not to the sea-level values because of the increased hemoglobin and lower heart rate.

altitude acclimatization; cardiac function, work and altitude; hypoxia and cardiac output

Submitted on July 29, 1963
A bag-in-box system for maintaining gases at body temperature within the body plethysmograph
Authors: Sackner Marvin A. , Feisal Khalil A. , DuBois Arthur B.
Published: December 2017

Measurements of the tissue volume and CO2 dissociation slope of the lungs by a plethysmographic technique require maintenance of the inspired gases at body temperature and saturation with water. For such a purpose, the design of a thermostatically controlled bag-in-box system which introduces negligible dead space between the mouth and bags is described.

apparatus for measurement of pulmonary tissue volume; bag-in-box system with negligible dead space; thermostatically controlled bag-in-box system

Submitted on August 26, 1963
An improved suction electrode for recording from the dog heart in situ
Authors: Churney Leon , Ohshima Hisashi
Published: December 2017

Action potential recordings by suction electrodes are generally small, unstable, and replete with artifacts like afterpotentials and incorrect values of the action potential overshoot. These electrodes record from the surface of the tissue plug imbedded in the electrode opening. This plug was found to have high electrical impedance, which accounts for the undesirable features of the recordings. The improved electrode yields negative-going resting potentials, and action potentials of 70–80 mv, routinely and for periods of 3–4 hr. The value of the overshoot compares with that recorded by glass microelectrodes. Afterpotentials are absent. The improvement results from the fact that the recording wire bypasses the tissue plug and is presumably recording from live, if injured, cells. We corroborate the important finding (B. F. Hoffman et al. Am. J. Physiol. 196: 1297, 1959) that the falling limbs of action potentials recorded simultaneously by suction and microelectrodes are coincident.

cardiac electrophysiology; suction electrodes and microelectrodes

Submitted on December 12, 1963
Plasma and red cell volume after prolonged severe exercise
Authors: Åstrand Per-Olof , Saltin Bengt
Published: December 2017

On six subjects plasma volume (Evans blue space) was determined before and 1 hr after an 85-km race in cross-country skiing. The total water loss during the 5- to 9.5-hr competition was estimated to be 5.9 liters, and at the time of measuring the reduction in body weight was 3.9 kg or 5.5% of the weight. The plasma volume was increased 0.41 or 11% (0.01 > P > 0.001). A similar study was undertaken with measurements of red cell volume (Cr51) on five subjects. The decrease in red cell volume was 0.081 or 3.2%. These findings are discussed in light of the small reduction in aerobic work capacity in combination with a marked decrease in total work output after the race. In five workers in a steel mill (three at a hot bank and two at a smelting furnace) the total water loss during an 8-hr shift in a hot environment was 3.9 liters and the reduction in body weight was 1.1 kg or 1.9% of the weight. The blood volume (I131) was increased by 0.23 liters or 3.5%.

dehydration; blood volume

Submitted on October 16, 1963
Effects of mass loading the respiratory system in man
Authors: Sharp J. T. , Henry J. P. , Sweany S. K. , Meadows W. R. , Pietras R. J.
Published: December 2017

Mass loading of the thorax in four normal conscious subjects and in six anesthetized paralyzed subjects transposed the thoracic volume-pressure curve to higher levels on the pressure axis without greatly affecting the slope of its linear portion. This effect is similar to that produced by forward acceleration and snorkel breathing. Mass loading the lower thorax produced a greater effect than mass loading the upper thorax. Mass loading the abdomen flattened the slope of the linear portion of the thoracic-volume pressure curve both in conscious subjects and in anesthetized paralyzed subjects, the effect resembling that of elastic loading which also flattened the thoracic volume-pressure curve. The shape of the total respiratory static volume-pressure curves in six of ten excessively obese subjects resembled that produced by thoracic mass loading in normal subjects. Five patients with the obesity-hypoventilation syndrome had curves suggesting a combination of elastic and mass loading or alternatively, abdominal mass loading. At any lung volume, the total transrespiratory static pressure is made up of a volume-dependent elastic component and a volume-independent gravitational component. The latter is approximately 5 cm H2O in the supine adult male of normal weight.

thoracic compliance; total respiratory compliance; gravitational effects on thorax; respiratory compliances in obesity

Submitted on January 6, 1964
Diffusing capacity of the lung in pulmonary emphysema
Authors: Ayres Stephen M. , Buehler Meta E. , Armstrong Ruth G.
Published: December 2017

Steady-state CO and O2 methods for measuring pulmonary diffusing capacity may be affected by abnormal distribution of inspired gas relative to perfusion. These methods frequently fail to separate abnormalities in diffusion from abnormalities in distribution in patients with obstructive emphysema. A rebreathing CO method has been developed which, in theory, is less sensitive to inequalities in distribution. The DlCO by this method in 41 normal subjects averaged 20.8 ± 8.6 ml/min mm Hg and was closely correlated with body size and lung volume. Only 3 of 25 patients with obstructive emphysema had a DlCO less than the 95% confidence level although the mean value for all of the patients (16.8 ml/min mm Hg) was significantly lower than that of the normal group. It is concluded that loss of diffusing surface is not a common cause of oxyhemoglobin desaturation in obstructive emphysema.

diffusion; carbon monoxide; ventilation-to-perfusion; gas chromatography

Submitted on December 27, 1963
Use of a cross-circulation technique in studying respiratory responses to CO2
Authors: Michel C. C. , Kao F. F.
Published: December 2017

The effect of hypercapnia and hypocapnia on ventilation was investigated in cross-circulated dogs in which the recipient dog's head and neck regions were perfused by blood from a donor dog. Hypercapnia of the donor dog was produced by administering CO2-O2-N2 gas mixtures in the inspired air. Hypocapnia was produced by hyperventilating the donor dog with the aid of a respiratory pump. When the donor dog was hyperventilated, the ventilation of the recipient was maintained at or just below its resting level and it was independent of the arterial Pco2 of the donor. The donor dog was apneic when the artificial hyperventilation was suspended and this response was not abolished by vagotomy. Bilateral vagotomy caused an increase in ventilation in the recipient when its head was perfused by hypocapnic blood. Bilateral removal of the carotid receptors did not influence the response to CO2 qualitatively although there was some reduction in the ventilation of the recipient to cephalic hypercapnia. The ventilation of the recipient dog was best correlated to the pH and Pco2 of its cerebrospinal fluid in both hypercapnic and hypocapnic states.

Note:

(With the Technical Assistance of S. S. Mei)

respiration; cerebrospinal fluid; apnea; central chemosensitivity; perfusion techniques; hypocapnia; hypercapnia; regulation of ventilation; chemoreceptors; hyperventilation

Submitted on February 19, 1964
Effect of sweat loss on body fluids
Authors: Kozlowski Stanislaw , Saltin Bengt
Published: December 2017

Six healthy men were studied under normal conditions and after dehydration caused by sweating produced 1) in a sauna at 80 C, 2) by hard muscular work at 18 C, and 3) by mild exercise at room temperature 38 C. The dehydration period lasted for 2.5@#X2013;3.5 hr. Sweat was collected in impermeable plastic bags around the forearm. Body weight, Evans blue space, and apparent inulin space were determined before and about 90 min after the dehydration period. The average decrease in body weight was 3.1 (4.1%), 3.1, and 3.5 kg for 1, 2, and 3, respectively. The reduction in apparent inulin space was 1.4, 0.2 and 1.3 liters, respectively. The decrease in Evans blue space paralleled the reduction in apparent inulin space. In the three conditions no significant differences were found in calculated total loss of electrolytes. Water liberated from combustion of fat and carbohydrates plus water previously stored with glycogen can account for up to 1.1 liters of the intracellular water loss during the hard exercise (2). The additional water loss from the cells is discussed in light of electrolyte shifts.

dehydration; intracellular fluid; extracellular fluid; plasma volume

Submitted on January 20, 1964
Elevation of mean circulatory pressure in dogs with cerebral ischemia-induced hypertension
Authors: Richardson Travis Q. , Fermoso Jóse D.
Published: December 2017

The Cushing reflex was elicited in 12 dogs. After the mean arterial pressures had become elevated, the mean circulatory pressures were measured. Mean circulatory pressure increased from the control of 7 mm Hg up to approximately 2.5 times the control when the mean arterial pressure was elevated to approximately 240 m

Cushing reflex; intracranial compression

Submitted on March 16, 1964
Factors influencing the concentration of expired nitrogen after a breath of oxygen
Authors: Mills R. J. , Harris P.
Published: December 2017

In normal subjects, the change in the concentration of nitrogen in expired alveolar air after a single breath of oxygen has been found to be affected by the presence of a pause at the end of inspiration, by varying rates of expiration, and by variations in the initial volume of air in the lungs. The effects of these different respiratory maneuvers are analyzed in terms of the over-all dilution of the inspired oxygen, of the unequal and asynchronous movements of the chest wall, and of the presence of a distribution of ventilatory time constants. The evidence suggests that there is a greater uniformity of ventilatory time constants at a middle lung volume than at a high or low lung volume.

distribution of ventilation

Submitted on January 27, 1964
Renal clearances at rest and during physical exercise after injection of bacterial pyrogen
Authors: Grimby Gunnar
Published: December 2017

Clearance of inulin (CIn) and para-aminohippuric acid (CPAH), cardiac output, oxygen uptake, and arterial blood pressure were measured in five healthy subjects at rest and during supine exercise on a bicycle ergometer before and after injection of a bacterial pyrogen (purified lipopolysaccharide, Pyrexal). CPAH was 45–145% higher at rest during the flush phase than in the normal condition. The increase in CIn, was less. Cardiac output increased also. The renal fraction of the cardiac output was larger than in the normal condition. During moderate exercise in the flush phase, CPAH decreased from the values before work. This decrease was usually larger than in the normal condition. The pyrogen-induced increase in cardiac output was less during exercise than at rest. A pronounced renal vasoconstriction during exercise is demonstrated even after the injection of bacterial pyrogen.

clearance of inulin and para-aminohippuric acid; cardiac output; extraction ratio

Submitted on May 4, 1964
Construction and use of self-guiding, right heart and pulmonary artery catheter
Authors: Fife William P. , Lee Bae Suk
Published: December 2017

A catheter has been developed which can be easily and rapidly implanted in the right heart or pulmonary artery. Fabricated from Tygon tubing, the catheter contains a thin section located 2 cm from the distal end. This results in a tip which follows the bloodstream without special manipulation. During implantation, its position is monitored by the use of a pressure transducer, thus eliminating the need for fluoroscopy. Since the catheter is self guiding, it may be implanted with ease from such distal locations as the femoral vein. It can be used to inject substances directly into the heart or pulmonary artery or to withdraw blood samples. It also can be used to make pressure recordings from these areas.

cardiac catheter; pulmonary pressure monitoring; right atrium pressure monitoring; right ventricle pressure monitoring; pulmonary artery wedge pressure; blood sampling from pulmonary artery; blood sampling from right ventricle; infusion into right ventricle; infusion into pulmonary artery

Submitted on February 10, 1964
Physical insulation of healthy men and women over 60 years
Authors: Lee Dae Yon , Hong Suk Ki , Lee Pyung Hee
Published: December 2017

Maximal body insulation [ I = (rectal temp. – skin temp.)/rate of skin heat loss] of healthy Korean men and women (17 each) over 60 years of age was determined by a method applied earlier to diving women of Korea (Rennie et al. J. Appl. Physiol. 17: 961, 1962). The critical water temperature was similar for males and females, ranging from 28–33 C. The water temperature at which 50% of subjects shivered was 31.2 C for both groups. This value is identical to that of young Korean men but is significantly higher than that of young Korean women. When a comparison was made at 31 C water, the extent of reduction in rectal temperature was, in the aged group, greater in males than in females, and was also greater in the aged than in the young. However, these differences could be accounted for mostly by the difference in subcutaneous fat thickness. When the values of I were considered as a function of the subcutaneous fat thickness, there was no difference either between old males and females or between the aged and young Korean subjects. This indicates that maximal body insulation due to physical factors does not change as a function of age.

Note:

(With the Technical Assistance of Jin Kyung Kim)

temperature regulation; aging process; subcutaneous fat; cold; shivering threshold

Submitted on January 15, 1964
Rate of lung collapse after airway occlusion on 100% O2 at various ambient pressures
Authors: Robertson William G. , Farhi Leon E.
Published: December 2017

The volume, time, and rate of collapse of the lungs following tracheal occlusion were studied in rats breathing O2 at ambient pressures between 1,520 mm (2 atm) and 190 mm (equivalent to 33,000 ft altitude). Theoretical calculations and experimental data show that 1) the rate of lung collapse is directly related to the O2 uptake and inversely related to the barometric pressure minus the sum of alveolar CO2 and water vapor pressure, and 2) the total time required for producing complete lung collapse is proportional to the lung volume at the time of occlusion and to the barometric pressure minus the sum of alveolar CO2 and water vapor pressure and inversely proportional to the O2 uptake. In both these relationships, lung volume is expressed at BTPS, while the O2 uptake is at STPD. The collapse time, with the lungs occluded at functional residual capacity dropped from 22.6 sec at sea level to 3.5 sec at 190 mm Hg. The rate of collapse was found to remain essentially constant during any experiment, as could be predicted from the analysis of the factors involved. The time required for collapse, in any species, at any lung volume and Vo2, can be determined with a nomogram.

atelectasis; altitude; oxygen breathing; gas resorption; O2 stores

Submitted on July 7, 1964
Effects of overhydration on man's physiological responses to work in the heat
Authors: Moroff Saul V. , Bass David E.
Published: December 2017

The question was asked whether men could work in the heat with less physiological strain if they drank water in excess of expected fluid losses than if they merely replaced their losses as they worked. Thirty volunteer soldiers walked on 2 successive days for 90 min at 3.5 mph on a level treadmill, at a temperature of 120/80 F dry bulb/ wet bulb. Each man drank 2,000 ml water before the walk on one day and no water before the walk on the other; 1,200 ml were drunk during the walk on both days. Overhydration resulted in significantly lower rectal temperatures and pulse rates and significantly higher sweat rates than did the control state. Two matched groups of six men each were then acclimatized to heat by daily 100-min walks under the conditions described above. One group was overhydrated during each day of the acclimatizing period; the other was not. Overhydration did not affect the pattern of acclimatization to heat; conversely, ac climatization to heat did not alter the above-described acute response to overhydration. The hypothesis that overhydration is beneficial to men working in the heat was supported by this study.

body temperature regulation; exercise; heat acclimatization; pulse rate; rectal temperature; sweat rate; hot, dry climate

Submitted on June 15, 1964
Heat reactions of male and female Caucasians
Authors: Wyndham C. H. , Morrison J. F. , Williams C. G.
Published: December 2017

Thirty male and twenty-six female Caucasians were tested at work levels of 1.0 liters O2 consumption in 90 F wet-bulb temperature, 93 F dry-bulb temperature, and 80 ft/min air velocity for comparative heat reactions in the unacclimatized state. The females had more severe physiological and psychological reactions. Rectal temperatures of 104 F and heart rates of 180 beat/min were reached more rapidly than in the male. The females sweated less and their oxygen consumptions were lower than those of the males. Ten males and four females were then acclimatized to the same extent at the same work rate in 93 F wet-bulb temperature. At the end of the period their reactions were closely similar, although the females responded slower to the acclimatization procedure. Both groups ended with heart rates of 140 beat/min and rectal temperatures of 102 F. The females, however, continued to sweat less. In a retest at 90 F wet-bulb temperature, both groups had heart rates of 130–140 beat/min and rectal temperatures of 101 F. Females still sweated less. The results demonstrate the fact that females react more severely on exposure to severe heat and work conditions. Once acclimatized, however, the temperature and circulatory reactions of both sexes are closely similar, but the females sweat less than males.

acclimatization of Caucasians to heat; Caucasians—acclimatization to heat; sex differences—heat reactions; physiological reactions to heat

Submitted on September 14, 1964
Preacclimatization of men to heat by training
Authors: Piwonka R. W. , Robinson Sid , Gay V. L. , Manalis R. S.
Published: December 2017

During April 1963, five distance runners from the Indiana University track team and one champion swimmer performed 85-min walks on a treadmill at 5.6 km/hr up a 5.6% grade in a hot environment (40 C DB, 25% relative humidity). Although none had been exposed to the heat since the preceding summer, the runners made responses typical of heat-acclimatized men. Untrained subjects exposed to the same stresses and the swimmer failed to regulate body temperature effectively. Although sweat rate was less in the runners than in the untrained men, it was 2.4 times greater per degree rise of rectal temperature for the runners. The runners produced 8% less metabolic heat per square meter of body surface than did the untrained men, and they also had much higher tissue heat conductance values. The swimmer's difficulty in adjusting to the heat stress was largely due to his relatively high metabolic cost in walking on the treadmill. It is thought that the preacclimatized state of the trained men probably resulted from the daily elevations of central temperature in their strenuous workouts during the preceding months.

acclimatization to heat; heat stress; hyperthermia; sweat rate; metabolic rate; tissue heat conductance; temperature regulation

Submitted on June 11, 1964
Hepatic clearance of indocyanine green in man under thermal and exercise stresses
Authors: Rowell Loring B. , Blackmon John R. , Martin Richard H. , Mazzarella John A. , Bruce Robert A.
Published: December 2017

At 78 and 110 F hepatic clearance of indocyanine green (ICG), O2 intake, heart rate, blood lactate, and rectal temperature were measure on nine men unacclimatized to heat during treadmill exercise, requiring 45–95% of maximal O2 intake (max Vo2). Percentage of resting ICG clearance was inversely proportional to percentage of maximal O2 intake at 78 F (ggr = -0.78) and 110 F (ggr = -0.81). Clearance of ICG was 20% less at 110 F than at 78 F at all metabolic rates above 26% of maximal Vo2. Measurements of hepatic blood flow in three men at 110 F validate these estimates of percentage decrements in hepatic blood flow. Submaximal and maximal Vo2 and maximal heart rates were unaltered by heat, but maximal heart rates were reached during submaximal work at 110 F. Decreased work capacity at 110 F was unrelated to rectal temperature or blood lactate; the latter was unaffected by temperature. The liver and the kidneys may divert to the skin sufficient blood to obviate the need for additional increments in cardiac output during work at high temperature. Maximal decrements in hepatic blood flow at lower work intensities may contribute to diminished work capacity at 110 F.

hepatic blood flow during exercise; lactic acid and heat stress; rectal temperature; heart rate and temperature; maximal o2 intake, influence of temperature; temperature redistribution of blood flow; work capacity, effect of heat

Submitted on October 30, 1964
Stability of cerebrospinal fluid pH in chronic acid-base disturbances in blood
Authors: Mitchell R. A. , Carman C. T. , Severinghaus J. W. , Richardson B. W. , Singer M. M. , Shnider S.
Published: December 2017

In chronic acid-base disturbances, CSF pH was generally within the normal limits (7.30–7.36 units, being the range including two standard deviations of 12 normal subjects). The mean values of CSF and arterial pHH, respectively, were: 1) metabolic alkalosis, 7.337 and 7.523; 2) metabolic acidosis, 7.315 and 7.350; 3) respiratory alkalosis, 7.336 and 7.485; and 4) respiratory acidosis (untreated), 7.314 and 7.382. Other investigators report similar values. The constancy of CSF pH cannot be explained by a poorly permeable blood-CSF barrier in chronic metabolic acidosis and alkalosis, nor can it be explained by respiratory compensation. It cannot be explained by renal compensation in respiratory alkalosis (high altitude for 8 days), although it may be explained by renal compensation in respiratory acidosis. The former three states suggest that active transport regulation of CSF pH is a function of the blood-CSF barrier. Since CSF pH is constant, so also must that portion of the respiratory drive originating in the superficial medullary respiratory chemoreceptors be constant. Ventilation changes in chronic acid-base disturbances thus may result from changes in the activity of peripheral chemoreceptors, in response to changes in arterial pH, arterial PO2, and possibly in neuromuscular receptors.

regulation of respiration; medullary respiratory; chemoreceptors; peripheral chemoreceptors; metabolic acidosis and alkalosis; respiratory acidosis and alkalosis; active transport; blood-brain barrier; pregnancy

Submitted on July 27, 1964
Electrode size and tissue pO2 measurement in rats exposed to air or high pressure oxygen
Authors: Jamieson Dana , Van Den Brenk H. A. S.
Published: December 2017

A comparison has been made of values of pO2 recorded in several rat tissues with 60-μ or 330-μ flexible gold electrodes. Although qualitatively both sizes of electrodes give similar results, the quantitative values of pO2differ. Such large differences as are found in some cases between electrodes varying only in physical dimensions are thought to reflect the amount of trauma caused in the tissue under investigation due to electrode insertion. Errors in pO2 estimations due to tissue damage are considered to outweigh any other errors such as those due to electrode calibration. Soft, highly vascular tissues, such as liver, kidney, and spleen, which show macroscopic bruising over quite a large area when electrodes are inserted, show the greatest difference in estimations of the pO2 value. Recordings of tissue pO2 were made while animals breathed air and when compressed to 4 or 5 atm in pure oxygen, and the pattern of response of tissue pO2 to such exposure of the animal to high pressures of oxygen is described.

values of pO2; flexible electrodes; tissue damage; compressed in pure oxygen

Submitted on July 24, 1964
Cholesterol metabolism. II. Quantitative measurement of cholesterol absorption
Authors: Bloomfield Daniel K.
Published: December 2017

A simple physiological method for quantitative study of cholesterol absorption is presented. The method uses the fecal bile acid tracer of dietary cholesterol-4-C14 as an index of cholesterol that has been absorbed, metabolized, and re-excreted. Since the fecal bile acid-to-sterol excretion ratio for rats on any specific diet is constant and can be measured, endogenous excretion of sterol can be calculated from bile acid values. Nonabsorbed sterol is the difference between total fecal sterol and endogenously excreted sterol. Although the method is described in rats, it is independent of species and is probably suitable for human use.

endogenous sterol excretion; fecal bile acids and steroids

Submitted on August 20, 1964
Hemodynamic study of myocardial heat transfer
Authors: Bleakley Paul L. , Reynolds Ernest W. , Yu Paul N.
Published: December 2017

The temperature difference (Tg) across the wall of the left ventricle has been studied in the dog by percutaneous left ventricular puncture. The temperature is higher in the epicardial layer than in the endocardial layer. A difference ranging from 0.20 to 0.70 C was found in all experiments. The TG was found to be stable over a long period of time and was not altered by infusion of isoproterenol or norepinephrine despite significant hemodynamic changes. On the other hand, the TG was reduced markedly when acute anemia or hypoxia was induced. The results with hyperoxia were inconsistent, although the TG was increased in half of the dogs studied. The magnitude of the TG is probably due to the effects and counteractions of many factors. These may include uneven heat production in different layers of the heart, insulation of the pericardium and chest wall, and rate of heat removal by the coronary blood flow and by left ventricular cavitary blood flow. In these experiments the fall in TG associated with anemia and hypoxia is assumed to be due to increased heat removal by the disproportionately increased coronary blood flow.

anemia; hypoxia; coronary blood flow; left ventricular heat production; left ventricular puncture

Submitted on August 3, 1964
Mechanism and pharmacology of shock due to rattlesnake venom in sheep
Authors: Halmagyi D. F. J. , Starzecki B. , Horner G. J.
Published: December 2017

Acute hypotension produced by the intravenous injection of 20 μg/kg of rattlesnake (Crotalus atrox) venom in sheep was spontaneously restored within frac12—2 hr (crotalin collapse). Slow continuous intravenous infusion of larger doses of crotalin produced a fall in cardiac output and systemic arterial pressure, hemoconcentration, and hypoventilation. This condition could only be reversed by therapeutic intervention and was termed “crotalin shock.” Administration of antivenin in crotalin shock proved to be ineffective. Intravenous dextran infusion restored cardiac output and accentuated respiratory depression. Administration of steroids in conventional therapeutic doses resulted in a rise in systemic arterial pressure and alveolar ventilation with little change in blood flow. Simultaneous administration of dextran and corticosteroids gave better results than either material used alone. Continuous intravenous infusion of isoproterenol improved alveolar ventilation and restored spontaneous breathing in some cases of crotalin-induced respiratory arrest.

dextran; ventilation; steroids; antivenin; isoproterenol; respiratory failure; hemoconcentration

Submitted on September 29, 1964
Skin temperature and cutaneous pain during warm water immersion
Authors: Hardy J. D. , Stolwijk J. A. J. , Hammel H. T. , Murgatroyd D.
Published: December 2017

Measurements of skin temperature were made during the sudden immersion of the skin of human subjects in water baths at 36–41 C and related to the reports of pain elicited during the first few seconds of immersion. Within 0.5 sec, the skin temperature rose to bath temperature and remained at this level during the 10–15 sec of immersion, pain was reported at 37–41 C occurring 1–5 sec after the start of the immersion and adapting in 2–6 sec. Calculation of the subcutaneous temperature and thermal gradients indicate maximal thermal gradients in superficial skin layers during the first 0.1–0.2 sec of immersion (60 C/mm) decreasing rapidly during the first 5 sec to 6 C/mm. Analysis of the transient pain indicated that it could be considered as the more sensitive “phasic” response of the pain ending of which the “static” unadapting response occurs at skin temperatures of 43–46 C. Several alternative explanations including subcutaneous thermal gradients, vasomotor reactions, and thermochemical changes in the nerve membrane were considered as possible explanations. The last most likely possibility requires a second-order kinetic system of three capacities with highly temperature-sensitive reaction velocities to account for both the phasic and static components of the pain.

thermal pain; transient pain; thermal gradients; protein destruction rates; mathematical model; adaptation of pain

Submitted on September 2, 1964
Decompression sickness following repeated breath-hold dives
Authors: Paulev P.
Published: December 2017

A report is given of a case of apparent decompression sickness after repetitive breath-hold dives to depths of 50–66 ft (15–20 m). Three similar cases in Norwegian Navy escape-training-tank instructors are also discussed. A parallel is drawn between the Scandinavian cases and the“pearl diver disease”(taravana), found in the Tuamotu Archipelago in the South Pacific. Symptoms and signs in these conditions are consistent with the diagnosis of decompression sickness. It is emphasized that in such cases immediate recompression is the treatment of choice. Consideration of various depths and patterns of breath-hold diving in terms of nitrogen uptake and elimination permits the relative risk of decompression sickness to be predicted with the help of decompression tables.

skin diving; recompression; repetitive diving; nitrogen uptake; taravana; nitrogen elimination

Submitted on September 25, 1964
Analysis of ventilatory response to CO2 during hypoxia in dogs
Authors: Honda Y. , Natsui T. , Hasumura N.
Published: December 2017

The response of the respiratory apparatus to CO2 during acute oxygen want was investigated in anesthetized dogs. The ratio of elevated ventilation to unit increase of PaCOCO2 in hypoxia to that in normoxia (SR) was taken as a measure of interaction between hypoxia and hypercapnia. Furthermore, the separate effect on ventilation by PaCOCO2 (DeltaAVR/DeltaPco2) and [H+] (DeltaAVR/DeltaH) during hypoxic hypercapnia was evaluated. a) SR increased in the presence of mild anoxia (80–50 mm Hg of PaOO2), then decreased in severe anoxia (less than 50 mm Hg of PaOO2). b) DeltaAVR/DeltaPco2 showed a higher value than the normoxia level in mild hypoxia (80–55 mm Hg of PaOO2), then progressively decreased with a further development of anoxia. c) DeltaAVR/DeltaH started increasing at about 70 mm Hg of PaOO2, then increased as the PaOO2 decreased, and reached about four times the normal at 30–40 mm Hg of PaOO2. The marked difference between isolated Pco2 and [H+] effect on ventilation in severe hypoxia suggested different areas and actions in the respiratory system of both chemical agents.

separate effect of [H+] and Pco2 on ventilation

Submitted on September 3, 1964
Effects of atelectasis on pulmonary surfactant and quasi-static lung mechanics
Authors: Levine Bernard E. , Johnson Rudolph P.
Published: December 2017

The effects of unilateral atelectasis on pulmonary surfactant activity and lung mechanics have been studied in rabbits. Total left lung collapse was produced by pneumothorax and maintained from 90 min to 8 days. Quasi-static pressure-volume relationships were determined with air and saline after varying intervals. Surface activity of minced lung extracts and of dried foam obtained by tracheal washings was measured on a surface balance. A marked decrease in lung inflatability progressing with duration of collapse was noted during air and saline pressure-volume studies. However, deflation characteristics of all atelectatic lungs were normal. Extracts from minced, in vitro reinflated atelectatic lung showed a variable but significant loss of surface activity compared to the right (normal) lung of the same animal. However, highly surface-active material could be demonstrated in the collapsed lungs by the more efficient extraction procedure of tracheal foaming. Correlation exists therefore between normal volume stability of alveoli after initial inflation and presence of surfactant activity in atelectatic lungs.

pressure-volume relationships; rabbit lung surface activity

Submitted on July 27, 1964
Stroke volume in conscious dogs; effect of respiration, posture, and vascular occlusion
Authors: Hoffman Julien I. E. , Guz Abraham , Charlier Andre A. , Wilcken D. E. L.
Published: December 2017

Right and left ventricular stroke volumes were measured beat by beat in tranquil, conscious, healthy dogs by electromagnetic flowmeter transducers implanted around the roots of the aorta and main pulmonary artery. The onset and time courses of stroke volume changes of each ventricle differed in response to respiration, passive change of posture, application and release of positive pressure, and occlusion of the inferior cava; the two ventricles were always out of phase and balance, and only appeared to be in phase when changes of heart rate dominated the picture. The immediate response to these events was probably determined by alterations in systemic venous return which changed end-diastolic fiber length and so altered stroke volume by the Frank-Starling mechanism. Changes of vagal tone might have played a small part by altering atrial contractility but sympathetic activity did not seem to be involved. The initial backflow in the pulmonary artery was taken as an index of the level of pulmonary vascular impedance and increased only when the transpulmonary pressure increased.

ventricular stroke volume; electromagnetic flowmeter; Frank-Starling mechanism; autonomic tone; backflow pulmonary vascular impedance

Submitted on December 3, 1964
Pulmonary diffusing capacity in man during immersion in water
Authors: Guyatt A. R. , Newman Faith , Cinkotai F. F. , Palmer J. I. , Thomson M. L.
Published: December 2017

During immersion in water to the neck, seven seated resting normal subjects showed, without exception in 14 trials, an increase in diffusing capacity of the lung (DlCO) which averaged 16.2 ± 0.79 sd % of the control (unimmersed) values (P < 0.001). At an intermediate depth of immersion at which the calculated hydrostatic pressure (gauge) was approximately halved, the rise in DlCO was also halved. The hemodynamic readjustment to external pressure was completed within a few minutes, since no further change in DlCO occurred during continuous immersion to the neck for as long as 90 min. Immersion produced a rise in “permeability” of the lung (Kco) which was on the average 5.8% greater than that in DlCO. In three subjects the pulmonary capillary blood volume (Vc) rose on the average 47% at the deeper level of immersion, suggesting that, as in the pressure suit, the rise in DlCO was due to pulmonary vascular engorgement.

pulmonary vascular engorgement

Submitted on July 6, 1964
Circulatory and respiratory effects of whole-body vibration in anesthetized dogs
Authors: Hood William B. , Higgins Lawrence S.
Published: December 2017

Effects of whole body x-axis sinusoidal vibration were studied in 27 anesthetized dogs. At a vibratory frequency of 10 cycles/sec and at levels of peak acceleration greater than 0.3 g, increases in the accelerative force of vibration were accompanied by increases in mean arterial blood pressure, heart rate, cardiac output, oxygen consumption, central blood volume, and minute volume of ventilation. Peripheral vascular resistance decreased under the same conditions. At 6 cycles/sec similar results were obtained, the only significant differences being in blood pressure and heart rate response. In three animals curare partially blocked the increase in oxygen consumption during vibration. Reserpine had no effect in two other animals. These studies suggest that the circulatory responses observed during whole-body vibration are due to muscular exercise.

vibration physiology; acceleration physiology; biomechanics; vibration and exercise; curare and vibration response; reserpine and vibration response

Submitted on February 1, 1965
Relation between changes of rib cage circumference and lung volume
Authors: Agostoni Emilio , Mognoni Piero , Torri Giorgio , Saracino Franco
Published: December 2017

The static relation between lung volume and rib cage circumference has been determined over the vital capacity range in standing, sitting, and supine position. The average change of circumference over the expiratory reserve volume in the three positions was, respectively, 20.7, 30.5, and 26.5% of the total change. The patterns of the volume-circumference curves have been discussed in terms of the different mechanical features of the rib cage and of the abdomen-diaphragm according to the lung volume and the position. The volume displacement of the rib cage, DeltaVrc, and of the abdomen-diaphragm, DeltaV(ab + di), at different lung volumes, have been calculated by a geometrical approach. These results agreed with determinations of DeltaV(ab + di) over the tidal volume range obtained by immobilizing the rib cage at resting volume. Over the expiratory reserve volume, DeltaVrc, in the three positions, was, respectively, 18.9, 27.8, and 40.7% of the lung volume change; over the vital capacity, DeltaVrc was, respectively, 39.6, 37.1, and 41.1.

effect of position and lung volume on the rib cage circumference; volume displacement of the rib cage and of the abdomen-diaphragm

Submitted on September 14, 1964
Pulmonary compliance and nonelastic resistance during treadmill exercise
Authors: Chiang S. T. , Steigbigel Neal H. , Lyons Harold A.
Published: December 2017

Trans-pulmonary pressure, respiratory flow, and tidal volume of seven normal subjects were measured at rest and during treadmill exercise on the level at a speed of 1.5 mph. Pulmonary compliance remained unchanged during exercise. Nonelastic resistance showed an insignificant increase (0.9—1.4 cm H2O per liter per sec). Examination of other parameters which may affect compliance were made. Functional residual capacity decreased 120—200 ml during exercise, tidal volume doubled, and respiratory frequency increased 43.5%, yet none of these factors affected the lung compliance. The phenomenon of “second wind” was experienced by four of the subjects, and nothing was observed to explain its occurrence during exercise.

exercise second wind; change in functional residual capacity during exercise; effect of functional residual capacity on compliance; effect of tidal volume on compliance during exercise; effect of respiratory frequency on compliance

Submitted on January 15, 1965