bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of airway resistance with a volume displacement body plethysmograph
Authors: Jaeger M. J. , Otis A. B.
Published: December 2017

Airway resistance was measured with a volume displacement body plethysmograph in 40 normal subjects breathing at their spontaneous breathing rate. The measurements are based on a method designed by DuBois et al. which was modified in order to extend its applicability. The subjects were rebreathing from a bag containing gas at approximately BTPS conditions. Possible errors in conditioning the gas in the bag were corrected mathematically. The values of airway resistance obtained (1.26 ± .39 cm H2O/liter-1 sec) agree with those published by DuBois et al. and other authors using his technique. The measurements were found to correlate with results obtained on the same subjects with related techniques. The paper also includes measurements of lung tissue viscous resistance and inertance of the gas in the airways.

respiratory mechanics; mechanics of breathing; airway inertance; lung tissue viscance

Submitted on November 22, 1963
Temperature in the external auditory meatus as an index of central temperature changes
Authors: Cooper K. E. , Cranston W. I. , Snell E. S.
Published: December 2017

The temperature of the wall of the external auditory meatus has been investigated. Changes in ear temperature reflect changes of sublingual temperature quite accurately and are well correlated with cutaneous vasomotor responses induced by body heating. The temperature of the external auditory meatus is little affected by reflex vasomotor changes. It is easily measured without discomfort or danger and provides a valid indication of temperature changes at the central receptors. There is a considerable temperature gradient down the wall of the meatus so that absolute temperature levels are probably not of value.

ear temperature in man; central temperature regulation in man

Submitted on February 24, 1964
Effect of cardiac denervation on the maximal capacity for exercise in the racing greyhound
Authors: Donald David E. , Milburn Sidney E. , Shepherd John T.
Published: December 2017

Ten consecutive time trials were run at 2-day intervals by six racing greyhounds over a 5/16-mile track. Cardiac denervation was then performed on four dogs, and a sham operation that included removal of the pericardium was performed on two dogs. After cardiac denervation, one dog died and another was rejected from the study because of a massive intrathoracic hemorrhage. The time trials were repeated with the addition of telemetry of the heart rate in the four survivors. There was no significant difference between mean preoperative and postoperative race times in the control group. The mean postoperative running speeds of 33.6 and 33.3 mph in the denervated group, although representing a significant slowing of 1.1 and of 2.1 mph, respectively, from preoperative values, indicate the adequate manner in which the denervated heart meets the circulatory demands of maximal running effort.

cardiac output; heart rate and exercise

Submitted on March 11, 1964
Limitations to prediction of maximal oxygen intake
Authors: Rowell Loring B. , Taylor Henry L. , Wang Yang
Published: December 2017

The predictability of maximal O2 intake (max Vo2) was studied in four groups of normal men, 18–24 years of age. Prediction of max Vo2 was made from pulse rate and Vo2 at a single submaximal workload at an ambient temperature of 78 F by use of the nomogram of Åstrand and Ryhming (1954) and underestimated actual max Vo2 by 27 ± 7% and 14 ± 7% in a sedentary group, before and after 2frac12–3 months of physical training, and by 5.6 ȁ 4% in a group of ten endurance athletes. Accuracy of prediction in all groups varied with approximation of pulse rate to 128 beats/min at 50% of max Vo2. Nonspecific stresses increased predictive errors in all groups. Constants b (slope) and A (intercept) in the regression equation Vo2 = bP – A (where P is pulse rate), were determined from Vo2 and pulse measured at four submaximal workloads requiring 13–28 ml O2/kg min. Prediction of max Vo2 by extrapolation of the slope to maximal pulse rate resulted in underestimation of 700–800 ml O2/min. Removal of 14% of circulating hemoglobin decreased max Vo2 by 4% but there was no change in pulse rates or predicted max Vo2. The relationship of RQ to V22 during work provided no reliable basis for prediction of max Vo2.

exercise pulse rate, oxygen intake, relationship; pulse rate, oxygen intake relationship in exercise; metabolic rate, maximal aerobic prediction of; aerobic metabolic rate, maximal, prediction of; phlebotomy, effect on maximal oxygen intake, pulse rate; blood loss, effect on maximal oxygen intake, pulse rate; training, effect on maximal oxygen intake, pulse rates; physical conditioning, effect on maximal oxygen intake, pulse rates

Submitted on October 4, 1963
Basal metabolism and respiration in men living at 5,800 m (19,000 ft)
Authors: Gill M. B. , Pugh L. G. C. E.
Published: December 2017

Respiratory determinations were carried out on eight members of the Himalayan Scientific and Mountaineering Expedition 1960—1961 and three Sherpas during a prolonged stay at 5,800 m (19,000 ft). Ventilation and oxygen uptake were similar in both groups, although the Sherpas were smaller men. The Sherpas had lower alveolar ventilation, higher PaCOCO2 and lower PaOO2 values than the scientists. Among six of the scientists mean basal metabolic rate was 10% above the mean value predicted from sea-level standards. There was no increase in the two others, who did not acclimatize. The mean basal metabolic rate in the three Sherpas was +21%. The findings were not explained by the extra O2 cost of increased breathing, changes in body composition, or exposure to cold, although this may have been a factor in the Sherpas. The results were similar to recent South American data on residents at 4,540 m (14,900 ft). It was concluded that acclimatization to great altitudes in man is associated with increase in basal metabolism, but there is insufficient evidence as to whether this is a response to hypoxia or other environmental factors.

basal respiration; acclimatized men; high altitude (5,800 m)

Submitted on March 30, 1964
Influence of gravitational forces on function of lower extremity muscles
Authors: Houtz S. J.
Published: December 2017

Action potentials were recorded by surface electrodes from the quadriceps, hamstrings, tibialis anterior, and triceps surae muscle groups as 12 normal adolescents performed a series of changes in posture. Postural movements consisted of sitting, standing, squatting, sit-ups, unilateral standing with contralateral lower extremity exercise, trunk forward bending with knee flexion and extension, and the head stand. Photographs were taken to assist in analyzing change in body position during the activities. The hamstrings and triceps surae resist forces tending to flex the supporting extremity when the trunk or contralateral limb is suspended anteriorly. The quadriceps and tibialis anterior act volitionally or by lengthening contraction to move the body vertically. The muscles participating in an activity and their specific functions are influenced by gravitational forces, the weight and position of various body segments, and the point of contact with the supporting surface.

electromyography; thigh and leg muscles; postural exercises; human male and female

Submitted on February 3, 1964
Modification of thermoregulatory responses to cold by hypnosis
Authors: Kissen Abbott T. , Reifler Clifford B. , Thaler Victor H.
Published: December 2017

The effects of hypnosis on thermoregulatory responses were studied in nonacclimatized acutely cold-exposed men. Forty exposures (4.5 @#X2013;5.0 C) were conducted in an environmental chamber under both hypnosis and nonhypnosis conditions. Five subjects, wearing 1 clo insulation, were cold exposed for 1 hr, four times for each condition, and each subject served as his own control. Variables monitored included mean skin and rectal temperatures, heart and shivering rates, basal skin resistance, and vigilance task performance. In hypnosis, shivering was suppressed, heart rate lowered, and vigilance task performance improved. Basal skin resistance differed in terms of pattern and level, being generally higher under hypnotic conditions. Rectal temperatures were lower despite maintaining skin temperature at the same level as during nonhypnosis conditions. These findings indicate that with the thermal stress imposed and levels of trance achieved, there is a general amelioration of the psychophysiological effects of the stress. The mechanism responsible for this form of “adaptation” remains speculative but is consistent with generalized suppression of sympathetic activity.

thermoregulation; cold exposure; adaptation; sympathetic nerve activity; shivering; basal skin resistance; vigilance task performance

Submitted on March 12, 1964
Reactions to heat of aborigines and Caucasians
Authors: Wyndham C. H. , McPherson R. K. , Munro A.
Published: December 2017

A study was made of the physiological reactions to heat of samples of Australian aborigines and Australian Caucasians in the hot, humid tropics. Their results were then compared with those of unacclimatized and acclimatized Caucasians (South Africa). The Australian shows signs of a partial degree of acclimatization in that his heart rate and rectal temperature are lower and his sweat rate is higher than those of the unacclimatized South African Caucasian. The aborigine presents a less clear picture in that his rectal temperature is lower but his heart rate and sweat rate is the same as the unacclimatized Caucasian. A striking difference between the Caucasians and aborigines in Australia is the much higher sweat rates of the Caucasians. The lower sweat rates of the aborigine might result from the morphological feature of a greater surface area: mass ratio whereby he loses heat by radiation and convection more adequately than the Caucasian and therefore is able to conserve sweat; alternatively, he appears to have a more sensitively adjusted thermoregulatory control channel between rectal temperature and sweat rate.

acclimatization to heat in northern Australia; adaptation to heat of aborigines; Caucasians and aborigines in Australian tropics; heat reactions in the tropics; morphology and adaptation to heat

Submitted on February 28, 1964
Effect of alveolar hypoxia on pulmonary vascular resistance
Authors: Lloyd Thomas C.
Published: December 2017

The responses to graded hypoxia in 58 excised dog lung lobe preparations have been measured during constant perfusion and ventilation. When perfused with blood, alveolar hypoxia always evoked a pressor response, whereas a dilator response always appeared when a synthetic perfusate was used. Hexamethonium, atropine, and brom-lysergic acid diethylamide did not alter the pressor response; Dibenzyline appeared to diminish the response but this may have been due to the reversal of effect of any epinephrine present. A pressor response could also be produced with KCN. The response to alveolar hypoxia was shown to be unrelated to pulmonary arterial blood Po2, but the resistance increase was demonstrated to be in the precapillary vessels. The hypoxic pressor response was transient and easily depressed by a period of severe hypoxia even though pressor drug responses remained unchanged. The possibility of mediation of the arterial narrowing by a reflexlike mechanism is considered.

Note:

(With the Technical Assistance of Emily McCartney)

direct vascular effects of hypoxia; reflex vasoconstriction tissue hypoxia

Submitted on March 27, 1964
Aerobic and anaerobic work capacity after dehydration
Authors: Saltin Bengt
Published: December 2017

Ten subjects performed standard exercise tests at two submaximal loads and one maximal load before and 90 min after dehydration caused predominantly by 1) a thermal, 2) a metabolic, and 3) a combined thermal and metabolic heat load applied for 2.5@#X2013;4 hr. Each subject interrupted dehydration so that almost the same decrease in body weight was attained in the three situations (1.7@#X2013;4.6 kg). Oxygen uptake, heart rate, and concentration of blood lactate were measured during the exercise. At the submaximal loads there was no change in oxygen uptake after dehydration but the heart rates were significantly higher (mean difference 13 beats/min) and blood lactates were lower (from 0.5 after (1) to 1.6 (2) mmoles/liter). At the maximal load there were no significant changes in oxygen uptake and heart rate but work times decreased markedly (6@#X2013;4 min) as did blood lactates (14.0@#X2013;10.4 mmoles/liter) especially after exercise dehydration.

physical work capacity

Submitted on January 20, 1964
Circulatory response to submaximal and maximal exercise after thermal dehydration
Authors: Saltin Bengt
Published: December 2017

Data on cardiac output and stroke volume are given for four subjects at various levels of muscular work up to the individual's maximum. No significant difference was found between the dye-dilution and the acetylene methods. Three subjects were studied under normal conditions and after dehydration (exposure to heat with a reduction in body weight of up to 5.2%); circulatory data were measured at rest and during exercise at two submaximal and one maximal work load. The decrease in body weight was accompanied by a reduction in plasma volume of up to 25%. After dehydration, the major change in the hemodynamic response to work in a sitting position at the submaximal loads was a decrease in stroke volume and an associated increase in heart rate, so that the cardiac output remained almost unaltered. Both these changes were significantly correlated to the reduction in body weight and plasma volume. When after dehydration the submaximal work load was performed in a supine position, no increase in heart rate was noticed compared with that before dehydration. Dehydration produced no significant change in oxygen uptake, cardiac output, or stroke volume during maximal exercise in a sitting position. However, the maximal work time was much shorter and there was a marked decrease in maximal blood lactate.

comparison dye-dilution-acetylene methods; plasma volume; lactic acid

Submitted on August 12, 1963
Load and local muscular isometric endurance with occluded blood supply
Authors: Start K. B.
Published: December 2017

The isometric endurance of the palmar flexors was measured in 11 subjects who had the blood supply to the forearm occluded by means of a pressure cuff on the upper arm. The endurance load was determined as a percentage of the maximum strength of each muscle group and, in this study, varied from 35 to 85%. Load was graphed against endurance and equations were established for the relation which, under the conditions of high loading in the experiment, appeared to be linear.

contraction metabolism; strength as a predictor of endurance; contraction producing intramuscular vascular occlusion

Submitted on December 30, 1963
Influence of water temperature on oxygen uptake by swimming rats
Authors: Baker Mary Ann , Horvath Steven M.
Published: December 2017

Oxygen uptake and rectal temperature of ten rats forced to swim to exhaustion or for 45 min in cold, hot, and thermoneutral water were measured during swimming. In 20 C water rats swam for 12.6 min and had a final rectal temperature of 26.9 C. In 42 C water the mean swimming time was 14.1 min and the final rectal temperature was 42.6 C. All rats swam for 45 min in water of 37 C, and the final rectal temperature was not different from the preswim temperature. Oxygen uptake during swimming in 37 C water rose and stabilized at a rate of about three times basal in a pattern suggesting that the swimming work was moderate. Animals swimming in cold and hot water were exhausted before their oxygen uptakes stabilized, but the increasing oxygen uptakes during the early parts of these swims were similar to that in neutral water. It appeared that while the metabolic rate was adjusted to the level of work and was not greatly affected by severe changes in body temperature, alterations in body temperature profoundly influenced the duration of work in the hot or cold environments.

exercise and thermal stress; exercise metabolism

Submitted on March 23, 1964
Oxygen used in horizontal and grade walking and running on the treadmill
Authors: Dill D. B.
Published: December 2017

The net oxygen cost of level and grade running was determined in three men-the author and two champion runners. The horizontal costs for the three were in agreement at the lower rates and for the two runners at high rates. A curve enables one to estimate the cost of horizontal walking and running and also of the horizontal component of grade walking and running. With this as a basis the cost of the vertical component in grade walking was found to be 1.53 ml/m·kg for the author and 1.31 ml/m·kg for one of the runners in both walking and running. This latter value and the curve relating the cost of the horizontal component to the rate of walking and running were used to estimate the cost of grade walking and running for seven other champion runners. The estimates checked closely with the observed cost in five. Marathoner DeMar was more efficient and the seventh runner was less efficient than predicted.

champion athletes; work performance; work efficiency; oxygen cost of climbing

Submitted on April 13, 1964
Temperature coefficients for Pco2 and Po2 of blood in vitro
Authors: Nunn J. F. , Bergman N. A. , Bunatyan A. , Coleman A. J.
Published: December 2017

Temperature coefficients of Pco2 and Po2 have been determined experimentally for fresh human blood. Changes in Pco2 over 18 C conformed closely to an exponential change with Pco2 (hot)/Pco2 (cold) equal to 10 to the power of 0.019 x temperature difference. For change of Po2 in fully saturated blood the corresponding value for the exponential constant was 0.0052. In contrast to water, the changes during warming were not significantly different from those during cooling. The exponential constant for oxygen rose with decreasing hemoglobin saturation to 0.032 at 83%.

blood carbon dioxide tension; blood oxygen tension; polarography; temperature correction factors for blood

Submitted on March 11, 1964
Immediate respiratory response to sudden cooling of the skin
Authors: Keatinge W. R. , Nadel J. A.
Published: December 2017

Showers at 25 C and below increased ventilation in man and respiration often could not be controlled voluntarily during showers at near 0 C. The increase took place within seconds and was accompanied by an increase in arterial pO2. The response could be obtained from high decerebrate cats and is believed to be a reflex initiated by cold receptors in the skin and mediated at midbrain level. The chest and abdomen were the most sensitive areas in man, but chilling any large area on the trunk or limbs caused some increase in ventilation. Although the showers caused an inspiratory shift in respiration and a sensation of difficulty in breathing, they caused little increase in airway resistance and no decrease in pulmonary compliance.

respiration; reflex; cold showers

Submitted on May 15, 1964
Distribution of blood flow and the pressure-flow relations of the whole lung
Authors: West J. B. , Dollery C. T.
Published: December 2017

Effects of changes in pulmonary arterial (Pa), venous (Pv), and alveolar (Pa) pressures on the over-all pressure-blood flow relations of an isolated dog lung have been re-examined. In the preparation used, the distribution of blood flow was predictable from previous measurements with radioactive gases. The results showed that the pressure-flow relations of the whole lung were greatly affected by the distribution of blood flow within it. For example, the pulmonary vascular resistance (PVR) of the lung depended on whether all the lung was perfused with blood or not, and thus whether there was an unperfused zone at the top of the lung where Pa was less than Pa ( zone 1). Again the pressure-flow relations of the lung were shown to depend on how much of the lung had a Pv less than Pa ( zone 2), and how much had a Pv which exceeded Pa ( zone 3). The effects on PVR of changing Pv or Pa could be explained on this basis. No evidence of a critical closing pressure in the vessels of the expanded lung was found. It was concluded that although the over-all pressure-flow relations of the whole lung were complicated, the flow through individual vessels could be accounted for by the simple mechanical effects of pressures inside and outside the vessels.

hydrostatic effect; pulmonary vascular resistance; Starling resistor; vascular waterfall; critical closing pressure

Submitted on May 4, 1964
Physical work capacity of college women
Authors: Michael Ernest D. , Horvath Steven M.
Published: December 2017

Maximal exercise tolerance tests were given to 30 female subjects 17-22 years old. The test consisted of exercising 1 min at a work load of 300 kpm/min and increasing the work load 150 kpm/min each minute until the subject could no longer exercise. The maximal heart rate level averaged 184 beat/min with a range between 170 and 202 beat/min. The average maximal Vo2 was 1.78 liter/min or 29.8 ml/kg per min. The submaximal ventilatory measurements were similar for all subjects while the heart rate levels at the submaximal work loads differentiated the subjects when grouped according to maximal work-load capacities. Prediction of maximal work capacity could not be made for individuals from any single submaximal measurement. There was .56 correlation between body weight and maximal work capacity with only a .32 relationship between maximal Vo2 and Vo2 per kilogram body weight.

exercise tolerance of women; cardiorespiratory function of women during exercise; submaximal cardiorespiratory response; maximal cardiorespiratory measurements of women; response to maximal exercise; prediction of exercise tolerance

Submitted on May 5, 1964
Sudomotor and vasomotor responses to changing environmental temperature
Authors: McCook R. D. , Wurster R. D. , Randall W. C.
Published: December 2017

Male subjects clad only in shorts were exposed in a climate chamber to a slowly rising ambient temperature while sweating, cutaneous volume pulses, and skin, tympanic membrane, and oral temperatures were simultaneously recorded. Mean skin temperature was continuously computed electronically. After sweating and vasodilatation had become well established, the copper screen bed on which the subject reclined was rapidly moved from the hot chamber into another, 20–30 C cooler. The onset of neither sweating nor vasodilatation could be accurately correlated with tympanic membrane temperature since the latter was observed to be either increasing, unchanged, or even falling during the period of recruitment. In some experiments, vasodilatation preceded sweating, while in others, it followed. When the subject was rapidly moved from the hot environment to the cold, sweating promptly stopped on all of the test areas, and profound vasoconstriction appeared on the palm. Nonpalmer areas, however, showed little or no immediate change in the amplitude of the volume pulses. Mean skin temperature invariably started to fall, but only by a few tenths of a degree when cessation of sweating and palmar constriction occurred. Tympanic membrane temperature during the same period continued to rise for 1–3 min, and thus seemed unrelated to either vasomotor or sudomotor control under these circumstances.

sweating; cutaneous vasomotor responses; cutaneous vasodilatation; cutaneous vasoconstriction; tympanic membrane temperatures; mean skin temperatures; nervous control of sweating; nervous control of cutaneous vascular responses; bradykinin and sweating; bradykinin and vasodilatation

Submitted on August 13, 1965
Effects of core temperature upon duration of hibernation of Citellus lateralis
Authors: Twente John W. , Twente Janet A.
Published: December 2017

Continuous recordings of core temperatures by permanent thermocouples in 31 golden-mantled ground squirrels (Citellus lateralis) during the hibernating season indicate: 1) hibernating periods persisted longer at lower core temperatures, periods averaged approximately twice as long at 2 as at 11 C; 2) the duration of hibernating periods was relatively constant and predictable for individuals at given temperatures; 3) when two core temperatures were experienced during a single hibernating period and the time spent at each temperature expressed as a per cent of the predicted duration for each temperature, the sum of these percentages approximated 100%; and 4) less stimulus was required to evoke arousal as a hibernating period progressed. Based upon the time-temperature relationship, increased irritability as periods progressed and individual consistency, the termination of hibernating periods (arousal) was thought to be a triggering of the autonomic nervous system by an accumulation or depletion of factors exceeding the limits of the hibernating homeostasis.

ground squirrel; arousal; hibernation induction; irritability; partial arousal; stimulus to arousal; homeostasis; thermocouple, permanent implantation

Submitted on July 9, 1964
Aerobic work capacity in young Norwegian men and women
Authors: Hermansen Lars , Andersen K. Lange
Published: December 2017

This paper deals with the problem of assessing the range of variability in work capacity of young adult Norwegians. Successful male athletes average 4.8 liter/ min or 71 ml/min per kg body weight in maximal oxygen uptake, versus 3.2 liter/min or 44 ml/min per kg body weight for a group of sedentary living men. Female athletes average 3.3 liter/min or 55 ml/min per kg body weight, compared to 2.3 liter/min or 38 ml/min per kg body weight for sedentary women. Oxygen cost of bicycling at submaximal work rates was the same in athletes and nonathletes, but with a clear sex difference, the females possessing a better work efficiency. The linear relationship between heart rate and oxygen uptake becomes curved in the least fit subjects (the sedentary women) when the exercise loads approach the maximal niveau. The maximal heart rate was found lower in athletically trained subjects. The exercise-induced hyperventilation takes place at an oxygen uptake corresponding to 70–80% of the capacity, this being the same in both sexes and uninfluenced by athletics.

maximal O2 uptake

Submitted on March 23, 1964
Pressure-flow relationships in the ascending aorta and femoral artery of man
Authors: Patel Dali J. , Greenfield Joseph C. , Austen W. Gerald , Morrow Andrew G. , Fry Donald L.
Published: December 2017

Using a Kolin-Kado electromagnetic flowmeter and a 20-gauge needle connected to a Statham transducer, instantaneous blood flow and pressure were measured in the ascending aorta of 3 patients and in the common femoral artery of 11 patients. From the data obtained in the ascending aorta the peak blood flow, cardiac output, peak power, and stroke work were calculated. Harmonic analysis of the pressure and flow curves was carried out and the hydraulic input impedance series was calculated for each subject. The constant term (peripheral vascular resistance) was found to be about 12 times as large as the largest time-dependent impedance term. Similar analysis of the femoral artery data indicated: 1) the moduli of the hydraulic input impedance series dropped with frequency from an initially high constant term, and then varied slightly with frequency thereafter; and 2) the vascular resistance decreased to 75% of the control value during reactive hyperemia and increased to 232% of the control value following norepinephrine administration.

hydraulic input impedance

Submitted on June 4, 1964
Ventilation of liquid by the fetal lamb during asphyxia
Authors: Howatt W. F. , Humphreys P. W. , Normand I. C. S. , Strang L. B.
Published: December 2017

Experiments were performed on fetal lambs, exteriorized by cesarean section, to study the ventilation of liquid during and after periods of umbilical cord occlusion. It was found that during and after the occlusion, the fetal lamb made strong ventilatory efforts with pleural pressures up to -68 cm H2O, which resulted in the displacement of volumes up to 17 ml in a single gasp. The total amount of liquid ventilated during cord occlusion was less than during the ensuing recovery period, when episodes of regular breathing at frequencies up to 30/min occurred. The ventilation of liquid was limited mechanically by a high flow resistance and inertance. Estimates of the amount of mixing likely to take place between inspired liquid and lung liquid were made by the injection and withdrawal of aliquots of 0.9% NaCl containing tracer amounts of I131-labeled albumen. Although the amount of each injected sample which mixed with lung liquid was rather small, it could be estimated that the large number of breaths which occurred during recovery from asphyxia could cause significant washout of lung liquid.

initiation of ventilation; amniotic fluid; fetal lung

Submitted on August 3, 1964
Catecholamines in plasma and urine at high altitude
Authors: Cunningham W. L. , Becker E. J. , Kreuzer F.
Published: December 2017

The concentration of free epinephrine and norepinephrine in plasma and 24-hr urine samples, collected from members of the Dutch Monte Rosa expedition (July 1963) was investigated during 17 days at various altitudes up to 4,560 m. The results indicate that the levels of both plasma and urine catecholamines were elevated during the expedition, the plasma levels reaching a maximum towards the end of the 12 days sojourn at 4,560 m. In general there was a twofold increase in total catecholamine concentration in the samples collected at high altitude as compared to control values at sea level. This difference was due to a significant increase in the norepinephrine concentration; there was little change in epinephrine level.

epinephrine and norepinephrine; sympathoadrenal activity

Submitted on September 2, 1964
Splanchnic metabolism in exercising man
Authors: Rowell Loring B. , Masoro Edward J. , Spencer Michael J.
Published: December 2017

Using a single injection of indocyanine green dye, estimated hepatic plasma and blood flow were determined in six normal young males during the 30th to 60th min of exercise requiring 10–12 kcal/min (2.04– 2.49 liters O2 per min). Subjects were fasted 15–18 hours. During hepatic flow measurements four determinations of splanchnic A-V differences of triglyceride (TG), free fatty acid (FFA), phospholipid (PL), ketone bodies, and glucose were made from radial arterial and hepatic venous sampling sites. Splanchnic A-V concentration differences for TG and PL varied randomly with time from positive to negative values indicating no net production whereas FFA was uniformly taken up by splanchnic organs at an average rate of 64 μm/min. Average splanchnic ketone body production was 20 mg/min and glucose production averaged 295 mg/min. Complete oxidation by skeletal muscle of lipid substrate released by splanchnic organs could account for less than 5% of total caloric expenditure; glucose production accounted for an average of 10.4%. One to two determinations of splanchnic A-V lactate, CO2, and O2 concentrations in four men indicated continued uptake of lactate (average 50 mg/min) during exercise with RQ values approaching zero.

lipid metabolism; exercise, hepatic blood flow, and metabolism; energy metabolism

Submitted on January 15, 1965
Influence of age and sex on exercise cardiac output
Authors: Becklake Margaret R. , Frank H. , Dagenais G. R. , Ostiguy G. L. , Guzman Carole A.
Published: December 2017

Exercise cardiac output has been measured by an indirect Fick technique in 94 normal subjects (48 men and 46 women) whose ages ranged from 20 to 85 years. With increasing age, exercise cardiac output was found to be greater despite no such trend in oxygen uptake; in consequence, exercise arteriovenous oxygen difference decreased with age. These trends were seen in both sexes, though the age effects were apparent a decade earlier in men. In addition, in men the heart rate was lower and stroke volume higher with increasing age. By contrast, no age effect on exercise pulse rate was noted in women. When the sexes were compared, exercise cardiac output was higher in women of the younger two decades (20 to 39 years), a difference which was not apparent in subsequent decades.

sex differences in exercise cardiac output; age differences in exercise cardiac output; stroke volume during exercise; oxygen pulse during exercise

Submitted on January 13, 1965
Pressure-flow relations of human blood in hollow fibers at low flow rates
Authors: Merrill E. W. , Benis A. M. , Gilliland E. R. , Sherwood T. K. , Salzman E. W.
Published: December 2017

Suspensions of human red cells in citrated plasma, in Ringer solution, and in Ringer solution containing albumin were passed through straight and curved glass and plastic hollow fibers (diameter range, 100–1,000 μ). Pressure-flow relations were measured over the pressure range of 0.1– 800 mm water, corresponding to a shear stress range of 0.01– 80 dynes/cm2. The suspensions were tested simultaneously in a rotational viscometer. It was found that red cell suspensions exhibit a yield shear stress only if the plasma protein fibrinogen is present. Experimental pressure-flow data in hollow fibers were in excellent agreement with rotational viscometer measurements and with analytical predictions based on the assumptions that blood flows as a homogeneous continuum and that the velocity at the wall is zero. Effects of tube surface characteristics and curvature on the pressure drop-flow rate relation were not discernible.

microcirculation models; model blood flow; yield stress of blood; capillary blood flow and viscometry; fibrinogen and blood flow in hollow fibers; non-Newtonian flow of blood in hollow fibers

Submitted on July 20, 1964
Contribution of thebesian veins to the physiologic shunt in anesthetized man
Authors: Ravin Mark B. , Epstein Robert M. , Malm James R.
Published: December 2017

The purpose of the present study is to quantitate the contribution of the thebesian veins to the total physiologic shunt in anesthetized man. The subjects were adults, free of septal defects, who were undergoing a variety of open-heart procedures for the correction of diseased valves. The studies were completed following thoracotomy but prior to the placement of catheters. Subjects were anesthetized, intubated, and ventilated with a constant-volume respirator. Prior to blood sampling 100% oxygen was administered for at least 3 min. Samples were simultaneously drawn from the left atrium and the aorta and analyzed for Po2 with a microelectrode which had been calibrated with tonometered blood. Only studies in which aortic Po2 exceeded 150 mm Hg were accepted. Pco2 and pH were also measured. From the difference in Po2 between left atrium and aorta the contribution of left ventricular thebesian veins to the physiologic shunt was calculated using a modification of the shunt equation. Values found ranged from 0.12 to 0.43% of the aortic flow. Mixed thebesian oxygen content was assumed to be 6 vol % in this calculation, but the value chosen can be shown not to be critical.

physiologic shunt; A-a difference

Submitted on November 30, 1964
A comparison of ventricular weights and geometry in newborn, young, and adult mammals
Authors: Lee J. C. , Taylor F. N. , Downing S. E.
Published: December 2017

The weight of individual anatomic segments of the heart and calculated left ventricular chamber volumes have been studied in the hearts of 214 normal mammals of seven species (sheep, swine, dogs, cats, rabbits, guinea pigs, and rats). Comparisons have been made between newborn, young, and adult age groups. In addition, the heart weight-to-body weight ratio, percentage of right ventricular free wall weight in relation to left ventricular free wall weight (RVF/LVF), the relationship between calculated ventricular volume and weight and the left ventricular major minor axis ratios were examined in each age range. Heart weight (HW) in relation to body weight (BW) was greater in the newborn than adult in all species except the dog. HW/BW was twice as great in the adult dog as other species. In newborns RVF/LVF ranged from 55 percent in rats to 100 percent in puppies. Less species variation was present in adult hearts. Species with a more spherical adult LV configuration demonstrated a greater chamber mass-to-volume ratio. This may be attributable to greater wall tension.
Flow and age dependence of airway closure and dynamic compliance
Authors: Begin R. , Renzetti A. D. , Bigler A. H. , Watanabe S.
Published: December 2017

The influence of expiratory flow rate and age on the results of measurement of closing volume (CV) of the lung have been studied by a nitrogen single-breath method in 66 asymptomatic lifetime nonsmoking normal subjects between 20 and 82 yr of age. Normal was defined as having values for spirometric measurements within a 95% tolerance interval of reported predicted normal mean values. For the CV determination, inspiratory flow rate was held constant at 0.51/s and studies were carried out at expiratory flow rates of 0.25, 0.5, 1.0, and 1.5 1/s. Our results show that CV expressed as a percentage of vital capacity (VC) and the slope of the alveolar plateau increases with increasing flow rate and age. Dynamic compliance (Cdyn) at frequencies corresponding to peak flow rates of 0.5 and 1.5 1/s was also measured and correlated well with the CV results. Frequency dependence of compliance with aging was demonstrated. Nine smokers with normal spirometric measurements and abnormal CV %VC were also studied. Since the results of Cdyn measurement differentiated only two-thirds of the smokers from the normal population, we suggest that the CV method is probably more sensitive than the Cdyn method for the detection of small airway obstruction.
Longitudinal studies of aging in 37 men
Authors: Robinson S. , Dill D. B. , Tzankoff S. P. , Wagner J. A. , Robinson R. D.
Published: December 2017

The physiological adjustments of the men to both aerobic (5.6 km/h, up 9% grade), and maximal treadmill work were first determined when they were healthy college students, ages 18–22 yr. They were restudied at ages 40–44, and again at ages 49–53 yr. In the aerobic walk VO2 increased in proportion to weight gain, but efficiency did not change with age. The men who had gained most weight showed the greatest elevations of heart rate, blood lactate and “ventilatory equivalent,” and reductions of the “O2 pulse” in the walk. At age 50 mean “O2 pulse” in exhausting work had declined 13%, even though mean maximal heart rate had declined 15 beats/min from values observed in youth. At ages 40–44 yr mean VO2 max had declined 25% to values 12% lower than mean values reported in 1938 for men of this age. Eight of the men imporved an average of 11% in VO2 max between ages 40–44 and 49–53 yr; mean VO2 max of the others continued to decline with age. The five men who improved most had increased their participation in vigorous activities (tennis, squash, skiing, jogging, etc.) and had quit or reduced their smoking.
Inherited susceptibility of cattle to high-altitude pulmonary hypertension
Authors: Will D. H. , Hicks J. L. , Card C. S. , Alexander A. F.
Published: December 2017

This study examines the hypothesis that susceptibility of cattle to high-altitude pulmonary hypertension and heart failure (high mountain disease) is genetically transmitted. Eight offspring of cattle recovered from high mountain disease were considered “susceptible.” Eleven offspring of healthy cattle residing at high altitude were considered “resistant.” At the resident altitude of 1,524 m, 10-day-old susceptible calves had higher pulmonary arterial pressures than did resistant calves (34 vs.21 mmHg), but at 90 days of age the pressures for the two groups were similar (26 vs. 24 mmHg). After 64 days of exposure to an altitude of 3,048 m, the susceptible calves (87 +/- 7 (SE) vs. 40 +/- 3 mmHg). By 124 days at 3,048 m, all susceptible but none of the resistant calves had developed heart failure. The results indicated that susceptibility to pulmonary hypertension at high altitude was inherited. Susceptible cattle may provide a useful model of human hypoxic pulmonary hypertension.
Renal response to secretin
Authors: Viteri A. L. , Poppell J. W. , Lasater J. M. , Dyck W. P.
Published: December 2017

The effect of Jorpes secretin on the urinary volume, pH, and excretion of sodium, potassium, chloride, bicarbonate, titratable acidity, ammonia and phosphate was studied in five healthy male volunteers with and without simultaneous aspiration of duodenal fluids. A three- to fourfold increase in urinary volume and sodium excretion occurred within the first 30 min after secretin injection and this was accompanied by a significant rise in urinary pH in each instance. Urinary bicarbonate excretion increased from 55 plus or minus 13 to 395 plus or minus 33 mueq/30 min after secretin injection. Aspiration of alkaline duodenal contents was accompanied by an even greater postsecretin increase in urinary bicarbonate excretion. No significant changes in arterial pH or blood gases were detected throughout the study. These observations are compatible with a direct effect of secretin upon the renal tubular reabsorption of water, bicarbonate, and other ions, and could account for the transient alterations in urinary pH occurring in response to a meal.
Autonomic nervous system and adaptation to cold in man
Authors: LeBlanc J. , Dulac S. , Cote J. , Girard B.
Published: December 2017

The responses to cold hand test (blood pressure increase and tachycardia) and to a cold face test (blood pressure increase and bradycardia) were used to study the role of the autonomic nevrous system in cold adaptation in humans. The Eskimos (men, women, children) were shown to have a very weak sympathetic response to cold but the vagal response (bradycardia) was identical to that of white people. A group of mailmen from Quebec city living outdoors approximately 30 h/wk throughout the year was also studied. A significant decline in the cold pressor response and an enhanced bradycardia (cold face test) were observed at the end of the winter. Similarly the fall in skin temperature of the cheek was not as pronounced when the measurements were made in May compared to those made in October. A group of soldiers was also studied before and after an Arctic expedition. It was found that the bradycardia of the cold face test was also more pronounced after sojourning in the cold. These results indicate that repeated exposures to severe cold in men activate some adaptive mechanisms characterized by a diminution of the sympathetic response and a concomitant enhancement of the vagal activation normally observed when the extremities and the face are exposed to cold.
Effects of dry air and subsequent humidification on tracheal mucous velocity in dogs
Authors: Hirsch J. A. , Tokayer J. L. , Robinson M. J. , Sackner M. A.
Published: December 2017

The impairment of mucociliary transport by dry air breathing and the restoration of function with subsequent humidification of inspired air were investigated in anesthetized dogs. Tracheal mucous velocity was measured by a cinebronchofiberscopic technique. The breathing of dry air through an uncuffed endotracheal tube produced almost complete cessation of the flow of tracheal mucus after 3 h. Subsequent breathing of air at 38 degrees C with 100% relative humidity restored tracheal mucous velocity to control values by the end of and additional 3 h. Histologic examination of the trachea at the end of the 3-h dry air breathing period revealed focal areas of sloughing of the ciliated epithelium and submucosal inflammation. Although morphometry was not employed, the inflammatory changes appeared to have progressed during 3 h of breathing fully humidified air subsequent to the dry air breathing period. These findings were consistent with previous reports that the inflammatory response to injury of the tracheobronchial mucosa might be delayed and that the mucociliary transport system has a great deal of functional reserve. We found that an artificial heat and moisture exchanger placed on the proximal end of an endotracheal tube partially protects against the suppression of tracheal mucous velocity caused by dry air breathing.
Alternative method for measurement of arterial pressure in the rabbit
Authors: Morizono T. , Johnstone B. M. , Lulich C.
Published: December 2017

By using an electrical impedance plethysmorgraph and a pressure applicator to a rabbit's earlobe artery, it became possible to monitor the blood pressure for periods of several months. A study of the correlations of the blood pressure from carotid and ear was also made at varied blood pressures under different conditions which showed excellent correlations. This method could effectively replace the encannulation technique for monitoring rabbit's blood pressure in chronic experiments.
Blood viscosity and cardiac output in acute experimental anemia
Authors: Fowler N. O. , Holmes J. C.
Published: December 2017

The significance of blood viscosity alterations during anemia was evaluated in dogs under morphine-chloralose anesthesia. In group I, anemia (mean hematocrit 18.1 +/- 1.3 vol %) was produced by exchange transfusion with clinical dextran (avg mol wt 70,000). In group II, anemia was produced (mean hematocrit 19.9 +/- 0.88 vol %) with 500,000 molecular weight dextran, thus preventing the decrease in blood viscosity in group I. The cardiac output increase in group I (93.4%) with low-viscosity anemia was significantly greater than in group II (43.3%) with unchanged blood viscosity. Group III animals were transfused with a clinical dextran-red cell mixture, and group IV animals received a 500,000 mol wt dextran-red cell mixture. In group III, blood viscosity and cardiac output did not change. In group IV, blood viscosity rose and cardiac output fell significantly. The results suggest that a change in blood viscosity exerts a significant effect upon cardiac output, especially during acute dextran-exchange anemia.
Heat tolerance of exercising lean and obese prepubertal boys
Authors: Haymes E. M. , McCormick R. J. , Buskirk E. R.
Published: December 2017

Seven lean and five obese boys, aged 9–12 yr, exercised in four environments: 21.1, 26.7, 29.4, and 32.2 degrees C Teff. Subjects walked on a treadmill at 4.8 km/h, 5% grade for three 20-min exercise bouts separated by 5-min rest periods. Rectal temperature (Tre), skin temperature (Tsk), heart rate (HR), sweat rate, and oxygen uptake (VO2) were measured periodically throughout the session. Lean boys had lower Tre and HR than obese boys in each of the environments. Increases in Tre were significantly greater for the obese at 26.7 and 29.4 degrees C Teff. No significant differences in Tsk and sweat rate (g-m-2-h-1) were observed between lean and obese boys. Obese boys had significantly lower oxygen consumptions per kg but worked at a significantly higher percentage of VO2max than lean boys when performing submaximal work. Responses of the obese boys to exercise in the heat were similar to those of heavy prepubertal girls studied previously, except that the boys were more tolerant of exercise at 32.2 degrees C Teff than the girls. Lean boys had lower HR than lean girls in each environment, but lower Tre only at 32.2 degrees C Teff.