bluuebunny/crossref_metadata_2025 huggingface dataset:
Motor control of pulmonary airways studied by nerve stimulation
Authors: Olsen C. R. , Colebatch H. J. H. , Mebel P. E. , Nadel J. A. , Staub N. C.
Published: December 2017

To investigate the motor control of the pulmonary airways we combined electrical stimulation of the cervical efferent vagus nerves of cats and dogs with measurement of pulmonary resistance (Rl) and anatomic dead space (Vd), and with anatomic study of rapidly frozen lungs. Stimulus frequencies between 1 and 12/sec produced almost the full range of Rl responses in eight cats. The major constrictor response to stimulation of one vagus nerve was in the lung of the same side in dogs and cats. A decrease of Vd associated with the increase of Rl in five cats during bilateral vagal stimulation suggested that the Rl change resulted from a generalized or large airway narrowing, rather than a local constriction. In seven cats whose lungs were frozen at end inspiration during unilateral vagal stimulation, the lobar bronchi on the stimulated side were smaller in diameter than comparable bronchi of the other side. In only two of seven cats was there definite constriction of the small cartilaginous and membranous airways of the stimulated side by the criterion of longitudinal mucosal ridges; in two there was slight constriction and in the other three, no change. Respiratory bronchioles and alveolar ducts of frozen sections were not constricted.

pulmonary resistance; vagus nerve distribution; anatomy of pulmonary airways; vagus nerve impulse frequency; sympathetic nerve inhibition

Submitted on May 1, 1964
Heart rate response to held lung volume
Authors: Angelone Alfonso , Coulter Norman A.
Published: December 2017

It has been shown that respiratory sinus arrhythmia correlates fundamentally with lung volume changes. The correlation with thoracic circumference changes is incidental and quantitatively unreliable. Extensive measurements on one subject and limited measurements on four other subjects demonstrate the existence of a systematic relationship between heart rate and lung volume under reasonably static conditions, a high heart rate corresponding to the expiratory position and a low heart rate to the inspiratory position. This relation has been described successfully with an exponential equation.

heart rate and lung volume: exponential relation; heart rate: lung volume dependence; lung volume and thoracic circumference: calibration; respiration and heart rate: static lung volume effect; respiratory sinus arrhythmia: held lung volume and heart rate; sinus arrhythmia: static lung volume dependence; thoracic circumference and lung volume: calibration

Submitted on July 22, 1964
Lung volume for initiation of phonation
Authors: Hoshiko Michael S.
Published: December 2017

The percent of vital capacity at which phonation is normally initiated was investigated. Thirty normal young male and thirty normal young female adults breathed oxygen in a closed circuit respirometer in a standing position. Vital capacity, expiratory reserve, tidal volume for breathing, and phonation volume were determined for each subject. The mean percent of vital capacity at which phonation is normally initiated was found to be 49.7 for males and 50.3 for females. These values approximate end-inspiratory volumes during quiet breathing in the upright posture.

breath stream dynamics; communication; respiratory muscle activity; electromyography; respiration

Submitted on July 13, 1964
Effect of dimercaprol on oxygen toxicity in rats
Authors: Van Tassel Peter V.
Published: December 2017

Six groups of 10 male Holtzman rats were given doses of 10, 25, 40, 50, 75, and 100 mg/kg dimercaprol, respectively. Both times of onset of the first convulsion and survival times of treated animals exposed to 6 atm of oxygen were measured and compared with 50 untreated controls. As the dose of dimercaprol increased to 40 mg/kg, both the time of onset of convulsions and the survival time increased to a maximum, and then decreased with further increase in dosage until they reached control levels at a dose of 100 mg/kg. Other animals were given equivalent doses of the vehicle in which the dimercaprol was dissolved, while still others received an inactive analogue of dimercaprol (glycerol). Neither the vehicle nor the inactive analogue produced the protective effect seen with dimercaprol.

British antilewisite; hyperbaric oxygen

Submitted on August 7, 1964
A rate signal interpreter
Authors: Partridge Lloyd D. , Jones Richard F.
Published: December 2017

A simple, on-the-line device is described for converting an electrical pulse pattern into a continuous voltage output proportional to the instantaneous pulse rate. The special purpose circuit and an analog computer version are both given. Pulse rates varying by 30:1 are adequately measured. Multiple ranges are provided. A special feature is that a falling rate is followed as soon as the current interval exceeds the last completed interval. The circuit is stable and components are not critical.

impulse rate; rate measurement; instrumentation; interval measurement

Submitted on November 16, 1964
Voluntary dehydration in man
Authors: Greenleaf John E. , Sargent Frederick
Published: December 2017

The effects singly and in combination of heat, exercise, and hypohydration upon voluntary dehydration were studied in four acclimated, physically fit, young men. Voluntary dehydration is the delay in complete rehydration following water loss. Hypohydration refers to the state of decreased water content while the osmotic concentration of the body is maintained. Ad libitum drinking during the heat experiments was 146% greater than it was in the cool experiments. Hypohydration increased drinking 109% over the corresponding hydration experiment, exercise increased water intake 41% over resting. Hypohydration and exercise were less effective than heat in stimulating drinking. During the 4-hr experimental periods, the subjects did not or could not drink enough to compensate for the water lost. Regardless of the magnitude of the water deficit at the beginning of the recovery periods, the rates of rehydration were the same. The more stressful the experiment, the greater the water consumption and, in general, the longer it took to regain the lost water.

water balance; heat; exercise; drinking; hypohydration

Submitted on September 8, 1964
A small electrolytically driven infusion pump
Authors: Baumgarten A. , Curtain C. C.
Published: December 2017

An electrolytically driven infusion pump has been constructed in which the pressure of gas generated by electrolysis is used to propel the infusate at controllable flow rates. The unit has over-all dimensions of 12.5 x 4.0 cm and consists of a chamber containing the electrolyte solution in a polyurethane sponge inserted between platinum electrodes and a chamber containing a mercury battery which serves as the power source. The infusate is contained in 4.5-mm diameter polythene tubing wound about the body of the pump. A small polythene valve inserted between the tubing and an intravenous catheter prevents reflux of blood. The pump has a capacity of up to 25 ml and a flow rate of 0.5—25 ml/hr. It can operate in any position and is designed for use in human subjects and unrestrained animals.

portable infusion pump; self-contained infusion pump; nonmechanical pump

Submitted on November 9, 1964
Hair density, wind speed, and heat loss in mammals
Authors: Tregear R. T.
Published: December 2017

The heat loss from excised pelts of rabbits, horses, and pigs has been measured at various wind speeds. The temperature gradient through the fur was also measured. The thermal insulation of fur is highly dependent on the hair density (i.e., number of hairs/ cm2), and on the wind passing over its surface. If there are less than 1,000 hairs/cm2, an 8-mph wind penetrates deep into the fur, but at higher hair densities an 18-mph wind penetrates only a little way into the fur.

fur insulation; obstruction of wind by hair

Submitted on September 10, 1964
Permanent physiological fistula of the pancreas and other digestive glands
Authors: Pekas Jerome C.
Published: December 2017

A method and equipment are described for the preparation of a permanent-type fistula of the pancreas of animals which do not have a papilla of Vater, as the pig. It accommodates the continuous return of the secretion to the duodenum, thereby eliminating the dehydration, anorexia, and early death so common with a permanent fistula of the pancreas where the total secretion is lost from the animal. The type fistula used is unique in that a sensitive one-way valve was used to prevent the reverse flow of ingesta into the pancreas during intervals of high peristalic pressures in the duodenum. The same method has been used to a limited extent to prepare fistulae of the bile duct and isolated segments of intestine and stomach, and may be used for other physiological shunt experiments.

gastrointestinal; secretions; one-way valve

Submitted on January 16, 1964
A hot-wire microanemometer for measurement of air movements inside clothing
Authors: Krishnaswamy N. , Mani K. V. , Ranganathan S.
Published: December 2017

A hot-wire anemometer has been specially designed and fabricated for the measurement of the wind speed component of the microenvironment inside clothing. A copper-constantan thermocouple has been used for estimation of temperature. The constant-current method is used for measurement of air movement. The sensing element is mounted in a Perspex frame which can be strapped to the human body inside clothing. Speeds in the range 2–280 cm/sec have been measured with the instrument.

anemometer; thermocouple; air velocity inside clothing

Submitted on September 8, 1964
Method for recording ECG's in unanesthetized guinea pigs
Authors: Richtarik Alfred , Woolsey Thomas A. , Valdivia Enrique
Published: December 2017

A device for use in recording ECG's from guinea pigs is described. It is constructed of Plexiglas and consists of a base with four electrodes (separated by plastic ridges) on which the animal stands. The animal's activity is restricted by a removable box, the ends and top of which are adjustable to compensate for variations in animal size. The device permits recording of ECG's in rapid succession from quiet, unanesthetized animals in normal standing posture. Results obtained with the method are reported.

apparatus for guinea pig ECG; time relations guinea pig ECG; normal ECG, guinea pig; factors affecting quality of ECG recordings from guinea pigs

Submitted on October 21, 1964
An electromyographic electrode designed for identification of recording sites
Authors: Hart Benjamin L. , Kitchell Ralph L.
Published: December 2017

An electromyographic needle electrode was designed so that a marking substance could be injected through the electrode into the recording site. This made it possible to identify the recording site, in the muscle, at the termination of the experiment when a postmortem examination was performed. Colored petrolatum or mineral oil was used as a biologically inert marking substance. Some of the recording sites were readily located as long as 130 days after injection.

perineal muscles; electrode location

Submitted on October 22, 1964
A student laboratory exercise illustrating active transport across the small intestine
Authors: Wilson T. Hastings , DeCarlo Angela
Published: December 2017

A 7-year experience with student laboratory exercises dealing with intestinal transport in vitro is described. A single experiment which has evolved from trial and error in the student laboratory is given in detail. Everted sacs of small intestine from the golden hamster are incubated in flasks containing bicarbonate-saline with 10 mm glucose and 2 mm d- or l-tyrosine. Glucose and l-tyrosine are transported across the intestinal wall against concentration gradients; d-tyrosine is not, illustrating the stereospecificity of the amino acid transport system. A second experiment which illustrates the stimulation of vitamin B12 absorption by gastric intrinsic factor is briefly recorded. The student interest aroused and the high degree of satisfactory results make such experiments useful additions to the repertoire of student laboratory exercises in physiology.

intestinal transport; amino acid transport; B12 transport

Submitted on November 12, 1964
Respiratory oxygen debt and excess lactate in man
Authors: Thomas H. Duke , Gaos Carlos , Vaughan C. Wayne
Published: December 2017

The relationship between the respiratory oxygen debt and excess lactate, change in lactate, and change in lactate/pyruvate ratio was examined in 48 experiments in 13 patients and in 13 normal volunteers. The subjects exercised for either 4- or 10-min periods. The recovery period varied from 17 to 45 min. Methods of analysis of lactate and pyruvate were colorimetric in 18 experiments, enzymatic in 20 experiments, and both in 10 experiments. The correlation coefficients between respiratory oxygen debt and excess lactate, delta lactate, and change in lactate/pyruvate ratio were 0.83, 0.87, and 0.85, respectively, in the colorimetric determinations. The enzymatic group showed somewhat poorer coefficients of correlation for these same variables: 0.76, 0.77, and 0.83, respectively. However, none of these relationships were one-to-one, and the correlation coefficients were poor for all of these variables in both series when they were subdivided into two groups based on whether the respiratory oxygen debt was greater or less than 2.2 liters/m2.

excess lactate oxygen equivalents; change in lactate pyruvate; lactate/pyruvate ratio

Submitted on June 15, 1964
Changes in the aerobic capacity and body composition in obese boys after reduction
Authors: Šprynarová ŠtĚpánka , Pařízková Jana
Published: December 2017

Seven obese boys submitted themselves to a 7-week regimen of dietary restriction and regular exercise. Measurements were made at the beginning and end of the period. A significant drop in body weight was achieved by reduction of adipose tissue and also of lean body mass (LBM). The ratio of LBM to body weight increased. These changes were associated with significant drop of maximum oxygen consumption. The increase of the Vo2 max per kilogram of body weight and the drop of the Vo2 max per kilogram of LBM were not significant. Between the decrease of LBM and the drop of Vo2 max there exists a significant negative relationship; and between the decrease of LBM and the rise of the Vo2 max per kilogram of body weight, a significant positive relationship. The decrease of Vo2 max in these boys was not considered due to deteriorated circulatory or respiratory function but to changes in body composition.

maximum O2 consumption; body weight reduction; lean body mass

Submitted on February 17, 1964
A search for a pulsatile component in pulmonary capillary blood volume
Authors: Fowler K. T. , Maloney J. E.
Published: December 2017

An examination was made of externally detected radioactivity over the thorax of two human subjects after the infusion of red cells labeled with Cr51. An electronic gating technique was used which enabled the mean counting rate to be determined over various preselected time intervals within the cardiac cycle and a comparison made between the rates which obtained during each quarter of this. When counting over the heart the rates were 20—30% greater in diastole than in systole. When counting over rib 2 or rib 4 on the right side no significant variation in count rate could be detected. From this it was deduced that pulmonary parenchymal blood volume in these regions did not vary by more than ± 10% within the cardiac cycle. It was concluded that within the erect lung a proportion of closed capillaries exists in the upper zone, and that the distensibility of the small vessels is insufficient to explain the large vertical inequality of blood flow observed experimentally.

pulmonary circulation; parenchymal blood volume; pulsations in volume; distensibility of small vessels

Submitted on August 17, 1964
Relationship between chest wall and pulmonary compliance and age
Authors: Mittman Charles , Edelman Norman H. , Norris Arthur H. , Shock Nathan W.
Published: December 2017

Chest wall and pulmonary compliance were measured in 42 normal males aged 24—78 years. Measurements were made using the static method and the positive-pressure breathing method of Heaf and Prime. Chest wall compliance decreased significantly with age. Pulmonary compliance measured at functional residual capacity was similar in old and young subjects. As lung volume increased pulmonary compliance decreased more in the young than in the old. The latter age difference may result from a loss of lung elastic recoil in the elderly or may be due totally to the age difference in chest wall compliance. The observed age differences in lung compartment volumes can largely be accounted for by the decrease in chest wall compliance.

aging; chest wall compliance; lung compliance; static measurement of compliance; positive-pressure measurement of compliance; lung volumes; residual volume

Submitted on July 17, 1964
Effect of accelerative forces on avian embryogenesis
Authors: Besch E. L. , Smith A. H. , Goren S.
Published: December 2017

Fertile avian eggs from the domestic fowl and the Japan quail showed a measurable loss of weight and a reduction atchability when exposed to varying intensities of centrifugal force for 10 min. Both of these effects are proportional to intensity of the applied force. Coturnix (Japanese quail) chicks hatched from eggs exposed to centrifugal forces prior to incubation displayed no growth rate differences from those chicks from control eggs. Impact force necessary to cause failure of embryo development is in excess of shell failure stress. The effect of subacute acceleration and impact deceleration is not manifested in the same manner in embryonated as in fertile eggs.

mechanical force; impact deceleration; centrifugal force; avian eggs; hatchability; embryo development

Submitted on December 31, 1964
Effect of exercise on the cerebral circulation and metabolism
Authors: Zobl Eldred G. , Talmers Frederick N. , Christensen Raymond C. , Baer Lesem J.
Published: December 2017

Cerebral hemodynamics and metabolism were studied in 13 normal patients and 14 hypertensive patients at rest and during vigorous physical exercise. Cerebral blood flow was determined by the nitrous oxide method. The cerebral vascular resistance in normal and hypertensive patients remained remarkably constant during exercise despite a marked reduction in total peripheral resistance. Cerebral blood flow was relatively unaffected by the marked increase in cardiac output and the cerebral metabolism did not share in the increased total body metabolism. During vigorous physical exercise the brain behaved as a steady-state organ.

cerebral resistance; cerebral blood flow; cerebral oxygen consumption; exercise

Submitted on February 4, 1965
Mammalian ventricular function during submersion asphyxia
Authors: Ferrante F. L. , Opdyke D. F.
Published: December 2017

Page 569 : the sentence beginning on line 12, column 2, should read: The diving mammal deserves complete study, then, because he may well exhibit the ideal response to acute hypoxia when the source of oxygen is severely restricted as during submergence asphyxia.
Water flux across the rat jejunum and ileum
Authors: Berger Eugene Y. , Pecikyan Rene , Kanzaki Grace
Published: December 2017

The flux of tritiated water from mucosa to serosa and from serosa to mucosa was measured across the rat ileum and rat jejunum in an in vitro perfusion system. The rate at which the specific activity of tritiated water decreased with time was an almost linear logarithmic function in the ileal serosal bath, whereas under identical conditions the rate of decrease was plainly curvilinear in the jejunal serosal bath. In comparing the first 40 min to the subsequent 60–100 min, the flux from mucosa to serosa across the ileum increased by 6.7 ± 5.6% in 12 comparisons, while the flux across the jejunum decreased by 21.O ± 9.9% in 7 comparisons. These observations illustrate the pitfall in determining flux rates based on a single determination at the beginning and end of an observation period. They illustrate the necessity of setting experimental conditions to be able to obtain intervening determinations to have some assurance that flux has not changed during the period of measurement.

tritiated water flux
Resistance or conductance? Compliance or elastance?
Authors: Clément J. , van de Woestijne K. P.
Published: December 2017

Page 437: J. Clément and K. P. van de Woestijne. “Resistance or conductance? Compliance or elastance?” Page 438: variance of R′ should read : By definition, the variance s2 of R′ is E (R′ – Rhorbar')2 or E(R′)2 – Rhorbar'2. Equation 2 becomes:

(See PDF)

Equation 4 is then:

(See PDF)

or, since δV/V ≪ 1,

(See PDF)

and the variance of 1/R′, deltaV being 0:

(See PDF)
Effect of chronic hypobaria on isolated tracheal preparation
Authors: Souhrada J. F. , Dickey D. W.
Published: December 2017

Isolated tracheal preparation (ITP) has been studied from rabbits adapted to 24 days simulated hypobaria (PB = 395 mmHg), corresponding to an elevation of 17,000ft (5,000m). During this daily hypobaric exposure, the growth of these animals was continuous and final hematocrit reached 70%. After 24 days of hypobaric exposure, the sensitivity of ITP was tested to acute hypercapnia and acute anoxia. Acute hypercapnia was induced by aerating a muscle chamber with a gas mixture of 85% oxygen and 15% carbon dioxide. During that time, the PCO2 of the experimental solution increased from 24 to 66 mmHg with a corresponding change of pH from 7.39 to 7.10. ITP from rabbits exposed to chronic hypoxia reveals a greater sensitivity to acute hypercapnia as measured by active tension (AT max) and rate of tension development (dT/dt). Acute anoxia was induced by aerating a muscle chamber with a gas mixture of 95% nitrogen and 5% carbon dioxide. During 20 min of these conditions, the Po2 decreased from 520 to 25 mmHg. Although the contractility diminished at approximately equal rates in both groups in response to acute anoxia, preparation from animals exposed to hypobaria showed statistically a significantly greater ability to recover from the anoxic state.
Prediction of maximum expiratory flow rate from area-transmural pressure curve of compressed airway
Authors: Jones J. G. , Fraser R. B. , Nadel J. A.
Published: December 2017

The site of greatest airway deformation in dog lungs was located during maximum expiratory flow by use of tantalum bronchography, fiberoptic bronchoscopy, and airway pressure measurements. A series of area vs. transmural pressure curves for each of these segments of the airway was produced after stepwise changes in transmural pressure. Measurements of area were made using cinephotography to elucidate the effect of time on airway compliance. The maximum flow rate was calculated using the t = 0.1 s compliance curve of the airway. An equation was derived so that maximum flow (V) could be calculated from the area (A) and transmural pressure (Ptm) of the flow-limiting segment. This equation, V = K-A square root of Ptm, implied that if V were constant then A must vary as Ptm-1/2. It was demonstrated that the area-transmural pressure curve of the flow-limiting segment showed this relationship between A and Ptm and that the flow calculated from this equation and the data from the A-Ptm curve gave flows identical to those measured during maximum expiration. The phenomena of effort-independent flow and negative effort dependence are also explained in terms of the area-transmural pressure curve of the flow-limiting segment.
Effect of shape and size of lung and chest wall on stresses in the lung
Authors: Vawter D. L. , Matthews F. L. , West J. B.
Published: December 2017

Conflicting results have been reported on the changes in the distribution of pleural pressures caused by alterations of chest shape. To understand better the effect of shape and size of lung and chest wall on the distribution of stresses, strains, and surface pressures, we analyzed a theoretical model using the technique of finite elements. The study was in two parts. First we investigated the effects of changing the chest wall shape during expansion, and second we studied lungs of a variety of inherent shapes and sizes. We found that, in general, the distributions of alveolar size, mechanical stresses, and surface pressures in the lungs were dominated by the weight of the lung and that changing the shape of the lung or chest wall had relatively little effect. Only at high states of expansion where the lung was very stiff did changing the shape of the chest wall cause substantial changes. Altering the inherent shape of the lung generally had little effect but the topographical differences in stresses and surface pressures were approximately proportional to lung height. The results are generally consistent with those found in dog by Hoppin et al. (J. Appl. Physiol. 27: 863–873, 1969).
Circadian variations in the sweating mechanism
Authors: Timbal J. , Colin J. , Boutelier C.
Published: December 2017

Sweat rates and body temperatures of human subjects were measured at 0200, 1000, and 1800 h during a heat exposure of 90 min. The latent period of sweating was not significantly altered in the evening but significantly shortened during the night. Mean body temperature corresponding to the onset of sweating was nearer to the basal body temperature during the night, while during the day the difference between these two temperatures became larger. This phenomenon seems related to the circadian cycle of vasomotor adjustment, since during the night body conductance was higher than during the day and corresponded to a state of a vasodilatation similar to that observed at the onset of sweating. During the day, this situation was reversed. During steady state, the following changes were observed: sweating rate, night less than morning less than evening; skin temperatures, night less than morning less than evening; and rectal temperature increase, morning less than evening less than night. It is hypothesized that these changes are due to either different metabolic rates or an imbalance between heat gains and losses which preserve the circadian rhythm of the body temperature, even under thermal loads.
Reproducibility of dynamic compliance and flow-volume curves in normal man
Authors: Guyatt A. R. , Siddorn J. A. , Brash H. M. , Flenley D. C.
Published: December 2017

To evaluate methods proposed for the early detection of small airways obstruction. we have compared the precision of the forced expiratory flow-volume curve and of measurements of the frequency dependence of lung compliance in normal subjects, in 10 of whom these measurements were made on four occasions, and in 5 on two occasions. The maximal expiratory flow rate was highly reproducible, revealing consistent differences between these normal subjects, particularly when measured at 60% of TLC and corrected for differences in body size. The frequency-dependence measurements, expressed as the slope of the regression line relating dynamic compliance to frequency, showed much greater variation between repeated measurements in the same subject. Comparison with earlier published accounts is difficult in view of lack of quantitative data, but the variability between single measurements on different normal subjects appears to be similar to that which we have found when the results are expressed in a comparable manner. Dynamic compliance at a frequency of 1 Hz lay between 48% and 141% of the value obtained by extrapolation to zero frequency.
Ability of man to detect increases in his breathing
Authors: West D. W. , Ellis C. G. , Campbell E. J.
Published: December 2017

The ability of four normal subjects to detect increases in their ventilation was studied at rest and at two levels of exercise using a raised inspired Pco2 to further increase ventilation. Subjects signaled when the increase in ventilation was recognized. The average tidal volume (VT) at rest was 520 ml with a frequency of 14; these values increased to an average of 3,300 ml and 21 at the highest work load. There was no significant change in frequency with CO2. Detection occurred when the tidal volume increased by 700 ml (varying 550–890 between subjects but constant for any one subject at the three levels of ventilation.) Thus the appreciation of increase is proportionately more sensitive at higher levels of ventilation. Experiments in which the ventilation was increased by hypoxia or by following a visual demand, and observations of other sensations (oral, cerebral) indicate that the increase in vetilation is recognized through increased breathing rather than awareness of ventilatory stimuli.
Control of depth and frequency of breathing during baroreceptor stimulation in cats
Authors: Grunstein M. M. , Derenne J. P. , Milic-Emili J.
Published: December 2017

In 10 tracheotomized anesthetized cats during steady-state inhalation of various concentrations of CO2 and O2, the acute respiratory response to baroreceptor stimulation produced by transient inflation of a balloon placed in the descending aorta was studied. The latter induced a sudden rise in mean arterial pressure, ranging from 62 to 95 mmHg. At all PACO2 levels above 30 mmHg, elevation in arterial pressure was accompanied by an immediate drop in tidal volume (VT) and prolongation of the durations of inspiration (Ti) and total breath (Ttot). Breaths obtained during baroreceptor stimulation fell along the same VT vs. Ti and VT vs. Ttot relationships obtained in the normotensive state, suggesting that the lung volume-related vagal control of Ti and Ttot is unaffected by changes in arterial pressure. Since, for a given change in arterial pressure, a constant reduction in VT was obtained at all PACO2 levels above 30 mmHg, it can be concluded that the interaction between PACO2 and arterial pressure is additive. In three cats, at PACO2 levels below 30 mmHg, aortic obstruction resulted in brief periods of apnea. Following apnea, the control of Ti and Ttot was transiently offset, describing hysteresis pathways on the VT vs. Ti and VT vs. Ttot relationships.
An inexpensive Plexiglas metabolism cage for the squirrel monkey (Saimiri sciureus)
Authors: Cunningham W. L. , Severson A. B. , Munsinger R. M.
Published: December 2017

A light, sturdy, and inexpensive metabolism cage for use with the squirrel monkey (saimiri sciureus) is described. The design allows for efficient urine and feces separation, ease of maintenance, and little interference with individual and social behavior patterns. Standard laboratory procedures for reduction of sampling error are presented, as well as results of a pilot study using the described apparatus. The design of the cage is such that, with minor modifications, it can be utilized by other small primates.
Untrained females: effects of submaximal exercise and heat on body fluids
Authors: Senay L. C. , Fortney S.
Published: December 2017

Five untrained females having no history of heat exposure worked in a cool (16–20 degrees C db, 28% rh) environment on day 1 and a warm environment on day 2 (45 degrees C db, 28% rh). Exercise level (bicycle ergometer) was 30% of individual Vo2 max values and work time on both days was 45 min. Venous blood samples were obtained at rest, after 40 min of exercise and 25 min after exercise ceased. Analysis of blood samples indicated an 8.3% increase in Hct during exercise on day 1 and a plasma volume reduction of 12.8% though total circulating protein increased 11.5%. Except for K+ all parameters approximated control values within 25 min postexercise. On day 2, exercise in heat caused a 12% increase in Hct and a plasma volume reduction of 17.7%. Mean total protein did not significantly change from resting values. These data indicated that for a given % Vo2 max, untrained females suffer considerably greater reductions in plasma volumes than do exercised males. Similar to males, dilatation of the cutaneous vascular bed in unacclimatized females resulted in loss of protein from the vascular volume.
Dynamic stiffness profiles in the left ventricle
Authors: Kennish A. , Yellin E. , Frater R. W.
Published: December 2017

Diastolic pressure-volume (P-V) curves were calculated on a beat-to-beat basis in the open-chest, pentobarbital-anesthetized dog, using the technique of direct transmitral flow measurement previously described. P-V curves were constructed and the slope (dP/dV) was plotted vs. pressure and time. dP/dV was used as an index of stiffness in each heart and its instantaneous changes with time were followed throughout the diastolic period. The end-diastolic P-V relation based on points from successive cycles during volume loading was found to be exponential. In contrast, the instantaneous P-V relation during any one diastolic period was not exponential. That is, the dynamic dP/dV vs. pressure plot was nonlinear. In the normal heart, stiffness was characterized in early diastole by a negative dP/dV as the ventricle continued to relax, and then frequently decreased prior to a second stiffness rise with atrial augmentation. These findings can be explained by a model containing an element whose deformation is rate dependent, i.e., a parallel viscous element. Stiffness profiles in mitral stenosis where dynamic effects are minimized substantiate this conclusion.
Suturable gastrointestinal cannulas for animals of various sizes
Authors: Cramer C. F. , Couch R.
Published: December 2017

A new procedure in which gastrointestinal cannulas are prepared from suturable material improves in vovo methods and requires little machining. Substitution of a suturable material for rigid collars, previously used, prevents leakage, infection, and loss of the cannulas into the gut lumen. The technique has been successfully applied to rats, rabbits, and dogs; consequently it should be useful in animals of almost any size. Two designs of cannulas with descriptions of their implantation are presented. The first version fits into each end of a gut loop and is useful for perfusion, digestion, and secretion studies. The second version forms a sidearm through which feeding or sampling can be carried out at any point in the intestine or the stomach.
Lactic acid removal rates during controlled and uncontrolled recovery exercise
Authors: Belcastro A. N. , Bonen A.
Published: December 2017

After a standardized 6-min bicycle ergometer exercise (89% VO2max) lactic acid removal rates were compared during recovery at rest and exercies at 29.7, 45.3, 61.8, and 80.8% VO2max, and twice while the subjects (N = 7) regulated their own recovery exercise. Blood samples were taken after the standardized exercise and every 5 min during the 30-min recovery periods. During the controlled recovery periods lactic acid removal rates were dependent on the intensity of the recovery (Y‣ = 0.103 + 0.218chi - 0.464 X 10(-2)chi2 + 0.252 X 10(-4)chi3). Optimal removal was predicted to occur at 32% VO2max. Removal rates during the self-regulated recoveries were not different (P greater than 0.05), but these removal rates were faster than during recovery at rest and exercise at 61.8 and 80.8% VO2max (P less than 0.01). Removal rates during the self-regulated recovery and recovery at 29.7 and 45.3% VO2max were not different (P greater than 0.05). The subjects were therefore able to remove lactic acid effectively when selecting their own recovery exercise.
Time-motion and physiological assessments of ice hockey performance
Authors: Green H. , Bishop P. , Houston M. , McKillop R. , Norman R. , Stothart P.
Published: December 2017

Ice hockey performance was studied during 10 contests to assess time-motion characteristics and associated physiological changes that occur for each position. Depending on the position played, the actual playing time per game for forwards and defensemen ranged between 20.7 and 28.0 min. The number of shifts ranged from 14 to 21 with an average playing time of 85.4 s/shift. Further analysis of each shift indicated that there was an average of 2.3 play stoppages which averaged 27.1 s, producing a continuous playing time of 39.7 s. Telemetered recordings of heart rate during each shift revealed sustained rates of between 170 and 174 beats/min over the three periods of the game. For both the forwards and defensemen, values for blood lactates were highest during the first and second periods (x = 78.0 and 66.1 mg/100 ml), then declined considerably during the third period (x = 44.5 mg/100 ml). Blood glucose showed a similar tendency (x = 139.3, 133.7, 114.1 mg/100 ml), while hematocrit and total protein showed little tendency to change.
Failure of histamine antagonists to prevent hypoxic pulmonary vasoconstriction in dogs
Authors: Tucker A. , Weir E. K. , Reeves J. T. , Grover R. F.
Published: December 2017

The role of histamine as a mediator of hypoxic pulmonary vasoconstriction was examined in intact anesthetized dogs. Antagonism of histamine vasoconstrictor (H1) receptors with a classic antihistaminic drug (chlorpheniramine) failed to prevent or modify the pulmonary vascular responses to hypoxia (10% O2). Blockade of histamine vasodilator (H2) receptors with a newly synthesized blocking agent (metiamide) potentiated the vasoconstriction induced by hypoxia and prevented the normal increase in heart rate. Combined H1- and H2-receptor blockade also did not prevent or reduce the hypoxic pulmonary pressor response, although it did effectively abolish the cardiovascular actions of infused histamine. In other dogs, histamine infused (3.6 mug/kg per min) during hypoxia attenuated the pulmonary vasoconstriction induced by hypoxia. The results imply that, in the dog, histamine does not mediate hypoxic pulmonary vasoconstriction. However, histamine does appear to be released during hypoxia, and it may play a role in modulating the pulmonary vascular responses to hypoxia by opposing the hypoxia induced vasoconstriction. The results also imply that histamine may be responsible for the increase in heart rate during hypoxia.
Effect of exercise on cardiac output and distribution of uterine blood flow in pregnant ewes
Authors: Curet L. B. , Orr J. A. , Rankin H. G. , Ungerer T.
Published: December 2017

This study was designed to determine what effect physical training has on heart rate and stroke volume responses to exercise stress and to determine if exercise altered the distribution of uterine blood flow. Measurements were made in ten pregnant ewes at rest and immediately following exercise on a treadmill. Five ewes underwent physical training for 3 wk prior to measurement. An increase in heart rate with no change in stroke volume was observed following exercise in both trained and untrained ewes. Total uterine blood flow was not changed following exercise, but distribution was altered in favor of the placenta. Blood flow was evenly distributed within the placenta before and after exercise. The redistribution of flow to the placenta that occurs after exercise. tphe redistribution of flow to the placenta that occurs after exercise might represent a compensatory mechanism for the fetus.
Respiratory and other responses in subjects immersed in cold water
Authors: Cooper K. E. , Martin S. , Riben P.
Published: December 2017

Subjects have been immersed in water at 27 degrees C and 10 degrees C and while immersed their respiratory rates, minute volumes, and end-tidal PCO2 levels were measured. Measurements were made with the subjects at rest, exercising at approximately 0.8 liter oxygen-min-1, and very vigorously at 1.8–2.0 liters oxygen-min-1. Immersion in the cold water caused an increase in respiratory rate and a fall in end-tidal PCO2. At the moderate rate of exercise the hyperventilation persisted in relation to the oxygen demand and there was still a significant reduction in end-tidal PCO2. At the greatest rates of exercise, the end-tidal PCO2 did not differ from that obtained in similar rates of exercise in warm water. Preheating the subject in a sauna so as to increase skin temperature, with minimal change in body temperature, greatly attenuated the ventilatory and end-tidal PCO2 responses to cold water immersion. The significance of these findings is discussed.
An improved plethysmograph with servo control of hydrostatic pressure
Authors: Zink J. , Delaive J. , Mazerall E. W. , Greenway C. V.
Published: December 2017

One limitation of the conventional fluid displacement plethysmograph is that the hydrostatic pressure varies as recordings of volume change are obtained. Thus, use of this instrument can lead to inaccuracies that are proportional to the compliance of the biological system under study. This paper describes an improved design which utilizes a servo-control system and an open, mobile reservoir to ensure that the hydrostatic pressure is maintainedconstant as volume changes are recorded. The result is a device that succeeds in combining stability, sensitivity and accuracy in a fluid displacementplethysmograph.
Control of breathing in uremia: ventilatory response to CO2 after hemodialysis
Authors: Hamilton R. W. , Epstein P. E. , Henderson L. W. , Edelman N. H. , Fishman A. P.
Published: December 2017

The mechanisms responsible for the transient respiratory alkalosis which follows clinical hemodialysis were evaluated by studying the ventilatory response to carbon dioxide in chronic uremic patients, and in unanesthetized normal and chronic uremic goats. A significant increase in sensitivity to CO2 was found in acidotic uremic patients immediately (within 30 min) following hemodialysis (P less than 0.01). Sensitivity to CO2 returned to the predialysis value within 24 h. Lung volume and maximal breathing capacity were unchanged. A similar increase in sensitivity to CO2 was seen in nonacidotic uremic goats following hemodialysis. In the goats, these changes in sensitivity could not be explained by changes in cerebrospinal fluid acid-base status. Adding sufficient urea to the dialysate to prevent a fall in plasma urea concentration, eliminated this increase in sensitivity to CO2 in both uremic patients and goats. These results suggests that the transient respiratory alkalosis following hemodialysis is due to an increase in the sensitivity of the ventilatory response to carbon dioxide and is a consequence of dialysis-induced osmotic disequilibrium.
Effect of gas physical properties and flow on lower pulmonary resistance
Authors: Wood L. D. , Engel L. A. , Griffin P. , Despas P. , Macklem P. T.
Published: December 2017

We measured lower pulmonary resistance (Rlp) in eight dogs and three men breathing gas mixtures having different densities (p) and similar viscosities (mu). Rlp increased with gas density and with flow rate (V). In the dogs, these effects were not observed in lung segments subtended from 4-mm-ID bronchi; in more central airways, resistance varied approximately as (mup V)0.5. These results are compatible with Poiseuille flow in peripheral airways, and, in central airways, with flow resistance described by the equation of boundary layer growth. Rather than two discrete flow regimes, it is likely that flow patterns undergo a continual metamorphosis as Reynolds' numbers (Re) decrease between trachea and alveoli. Accordingly, the airways pressure-flow relationship is not described by any single fluid dynamics equation, but may be explained by the general equation, P = Kmu2-apa-1Va, where a reflects the proportion of inertial to viscous pressure losses and varies between 1 and 2 according to Re. Rohrer's equation described the observed pressure-flow relationships and predicted the change in Rlp with gas physical properties, suggesting a physical basis underlying this adequate mathematical description.
Sighing in newborn human infants: role of inflation-augmenting reflex
Authors: Thach B. T. , Taeusch H. W.
Published: December 2017

To investigate the reflex mechanisms of sighs (spontaneous large breaths)(VT greater than 2 X control VT) in infants, recordings of respiratory flow and tidal volume (VT) were made during sleep. The frequency of sighs was greater at 1 than at 5 days of age, while respiratory frequency and controlVT did not change. Most sighs (93%) had a biphasic pattern of inspiratory flow characterized by an inspiratory duration nearly twice that of control breaths, with an abrupt change in flow rate halfway through inspiration. Interruption of ventilation (3–7 s of airway occlusion) appeared to generate astimulus for biphasic sighs, since sighs occurred during the first breath after termination of airway occlusion more frequently after long thanafter brief occlusions. However, a biphasic inspiratory pattern in airway pressure was rarely observed while the airways were occluded, regardless of occlusion duration. This suggests that increase in lung volume during the initialpart of the biphasic inspiration following occlusion is a stimulus for the second part. Thus the underlying reflex mechanism of sighs in human infantsappears to be the same as occurs in the so-called Head's paradoxical response to lung inflation.
Ventilatory muscle strength and endurance training
Authors: Leith D. E. , Bradley M.
Published: December 2017

We studied respiratory mechanics in young volunteers before and after 5-wk training programs limited to the ventilatory muscles. Four strength trainers (S) performed repeated static maximum inspiratory and expiratory maneuvers against obstructed airways. Four endurance trainers (E) performed voluntary normocarbic hyperpnea to exhaustion. Subjects spent 30–45 min each day in these exercises, 5 days a week. Four control subjects (C) did no training. We attempted to minimize the effect of learning. S increased pressure maximums by about 55%, but vital capacity and total lung capacity by only about 4%. Initially all subjects could sustain hyperpnea at about 81% of their control 15-s maximum voluntary ventilation (MVV) for 15 min; E increased this to about 96% and increased their MVV by 14% as well. No other statistically significant changes were recognized in any group. We conclude that ventilatory muscle strength or endurance can be specifically increased by appropriate ventilatory muscle training programs.
Blood flow in branching vessels
Authors: Pinchak A. C. , Ostrach S.
Published: December 2017

Flow visualization studies were conducted in a water-Plexiglas tube model which simulated flow conditions commonly encountered in major vessels. Complex secondary flow patterns in the main line downstream of a branching vessel were observed in found to be relatively independent of the diameter ratio and angle of departure of the branching tube. The ratio of branching to total flow was the prinicipal determinant of the aforementioned secondary flows. Venous and arterial branching markedly differed. Arterial-type flows produced a pair of vortex sinks downstream of the branching port. These vortex-sink flow fields, which previously have not been reported, captured fluid particles already downstream of the branching orifice and returned these particles upstream to exit via the branching tube. In a region very close to the tube wall, streamlines were also observed moving upstream to be captured by the branching vessel. The interaction of this local upstream flow with the general downstream flow produced a pair of stagnation points located downstream and lateral to the branching orifice. These stagnation regions are discussed in relation to atheroma and thrombus formation.
Direct and indirect blood pressure measurements in baboons
Authors: McMahan C. A. , Wigodsky H. S. , Moore G. T.
Published: December 2017

The accuracy and precision of indirect blood pressure measurements in baboons were studied by comparing the results of indirect measurements with simultaneous direct measurements. The indirect measurements were made by four observers using a Doppler ultrasound instrument. A statistically significant difference between the two methods was found for systolic blood pressure but not for diastolic blood pressure. The indirect systolic averaged 13.8mmHg higher than direct systolic and was found to be more precise than the indirect diastolic. The difference in blood pressure obtained by the two methods varied over animals and observers with an interaction between animalsand observers. The effect of arm was examined by performing direct blood pressure measurements in both arms. No statistically significant arm effect was found.