bluuebunny/crossref_metadata_2025 huggingface dataset:
Potassium distribution and toxicity in hypothermia
Authors: Hoff Hebbel E. , Deavers Stephanie , Huggins Russell A.
Published: December 2017

Ten dogs were anesthetized with a combination of morphine and pentobarbital. Control arterial samples for serum potassium determinations were taken, and the animals were cooled to a mean rectal temperature of 27.9°C. At this point, a slow infusion of potassium chloride was started and was continued until the disappearance of the P wave on the continuously recorded electrocardiogram. Thirty minutes were allowed for equilibration. The apparent volume of distribution of potassium in these animals averaged 73% of the body weight. These values compared closely with values of 67% for normothermic animals receiving the same anesthetics and the same total amounts of potassium, but are lower than in similar animals given larger doses of potassium. Hypothermia lowered the lethal concentration of potassium in the serum to 8.9 mEq/l.

Submitted on December 9, 1960
Cardiac output in normal resting man
Authors: Reeves John T. , Grover Robert F. , Filley Giles F. , Blount S. Gilbert
Published: December 2017

Sixty-three measurements of cardiac output in 50 normal resting individuals utilizing pulmonary arterial catheterization and the classical Fick method were made to investigate the normal standards of cardiac output under these conditions. Variation between individuals in age, sex, body size and metabolic rate was great enough to render the cardiac index (cardiac output/ unit of body surface area) a rather insensitive standard of normal blood flow. Rather the variation was substantially improved by considering cardiac output to be linearly related to oxygen uptake. This direct relationship appeared to be the result of the A-V oxygen difference varying independently of oxygen uptake, metabolic rate and body surface area. The mean A-V oxygen difference was 39.8 cc/l. with one standard deviation of α5.8 cc/l.

Submitted on August 8, 1960
Circulatory changes in man during mild supine exercise
Authors: Reeves John T. , Grover Robert F. , Filley Giles F. , Blount S. Gilbert
Published: December 2017

Cardiac output and femoral A-V oxygen difference were measured in each of seven normal men at rest and during several stints of supine exercise to investigate the mechanisms of oxygen transport for stepwise increments of oxygen uptake. The femoral A-V oxygen difference increased sharply for mild exercise and showed smaller further increase for heavier exercise stints. The pulmonary A-V oxygen difference followed a similar behavior where the changes were of smaller magnitude. For mild exercise, increasing oxygen transport apparently depends to a greater extent on increasing femoral tissue oxygen extraction and to a lesser extent on increased femoral and total blood flow. For heavier exertion, increasing oxygen transport depends to a greater extent on increasing flow and to a smaller extent on a widening tissue oxygen extraction. Mechanisms which are utilized to meet the increased metabolic demands of exercise depend in part upon the severity of the exertion. Cardiac output appears not to be a simple linear function of oxygen uptake for various metabolic demands ranging from rest to heavy exercise.

Submitted on August 8, 1960
Cardiac output response to standing and treadmill walking
Authors: Reeves John T. , Grover Robert F. , Blount S. Gilbert , Filley Giles F.
Published: December 2017

Cardiac output measurements during cardiac catheterization were obtained in normal subjects for several grades of treadmill exercise. Femoral venous blood was sampled and the A-V oxygen difference for the exercising leg obtained. Measurements of central and femoral A-V oxygen difference and total oxygen uptake were also obtained in normal subjects during supine rest and during standing. When subjects merely stood, the A-V oxygen difference for the leg increased (whether the leg bore weight or not) much more than did that for the whole body. During treadmill walking femoral A-V oxygen difference was usually no greater than that during standing. Cardiac output was smaller and total body A-V oxygen difference was greater for treadmill walking than for supine bicycle exercise in which comparable levels of oxygen uptake were achieved. It is clear that change in posture alters the cardiac output response to exercise. An important aspect of the altered response was a marked difference in the circulation within the leg for these two postures both at rest and during exercise.

Submitted on August 8, 1960
Variations of ventilation and diffusing capacity to perfusion determining the alveolar-arterial O2 difference: theory
Authors: Piiper Johannes
Published: December 2017

The factors determining the alveolar-arterial O2 pressure difference, AaD, have been theoretically reinvestigated, taking into account the effect of unequal distribution of pulmonary diffusing capacity, D, to pulmonary perfusion, Q. It is shown that, for a given inspired gas and a given mixed venous blood, the AaD is determined by two parameters, the ratios diffusing capacity :perfusion, D/Q, and alveolar ventilation :perfusion, Va/Q. Two characteristics of both of these ratios, the mean value and the variation, affect the AaD.

Submitted on May 23, 1960
Velocity of O2 uptake by human red blood cells
Authors: Staub N. C. , Bishop J. M. , Forster R. E.
Published: December 2017

We have determined the over-all association rate constant, k'c, for the uptake of oxygen by normal human erythrocytes from 0% to 97% initial hemoglobin saturation at pH 7.4 and 37óC. With a modified Hartridge-Roughton rapid-reaction apparatus, we used a small oxygen electrode to follow the oxygen uptake process rather than using the usual photocolorimetric analytical methods. The value of k'c averages 164 mm-1 sec.-1 at 0% initial saturation, rises slowly to over 300 at 50%, and then climbs rapidly to over 1500 at 95%. The theoretical explanation for the increase in k-c with rising initial oxyhemoglobin saturation is based on the increasing prominence of the fourth chemical association rate constant, k-4, in the intermediate compound theory of Adair. It is known that k-4 is several times larger than any of the other three k–s.

Submitted on December 19, 1960
Body composition at sea level and high altitudes
Authors: PicÓn-Reátegui E. , Lozano Rodolfo , Valdivieso José
Published: December 2017

Simultaneous determinations of total body water and extracellular fluid, using the antipyrine and sucrose infusion methods, have been carried out in 28 adult male residents at sea level and in 28 residents at an altitude of 14,900 ft. Body composition was calculated from these data. The various body spaces, expressed in percentage of body weight, were similar in the two groups, with the exception of the extracellular fluid which was greater in those in the high altitude group ( P < 0.01). Neither racial characteristics nor altitude appear to be factors generally affecting body composition. In individuals having adequate caloric intake body composition seems to be influenced principally by physical activity. In fact, physical inactivity appeared to produce a loss of active tissue and its replacement by fat.

Submitted on November 2, 1960
Citric acid cycle in certain alterations of acid-base balance in human subjects
Authors: Gamble Wilbert , Orten James M. , Smith Arthur H.
Published: December 2017

An accurate chromatographic (silica gel) procedure for the quantitative measurement of the stable citric acid cycle acids and certain noncycle acids in urine was developed. The identity of the isolated acids was verified by paper chromatography. The method was applied to a study of urinary excretion of the cycle and other acids during certain alterations in acid-base balance in eight normal subjects, and one diabetic patient. During a “basic” regimen, the “alkaline tide,” and “respiratory alkalosis,” a significant increase in the excretion of citric acid occurred, with no significant change in that of the other cycle and noncycle acids. The “acidic” regimen produced a uniform decrease in the excretion of citrate to values approaching statistical significance; there was no consistent alteration in the excretion of the other acids. A similar decrease in the excretion of citric acid was observed in the patient during diabetic acidosis. It is concluded that of the Krebs cycle and other acids studied, the urinary excretion of only citric acid varies with alterations in acid-base balance.

Submitted on February 10, 1961
Dilution of alveolar gases during nitrous oxide excretion in man
Authors: Rackow Herbert , Salanitre Ernest , Frumin M. Jack
Published: December 2017

The effect of N2O excretion upon O2 and CO2 levels in man was studied during two different types of artificial respiration with air. When a constant inflating pressure type respirator was used, the average fall in end-tidal Pco2 was 2 mm Hg or 5%. The measured fall in alveolar Po2 could not be determined with confidence, although theoretical considerations indicate it to be greater than 5%. When the respirator was servo controlled by end-tidal CO2 in a manner closely analogous to the human central respiratory mechanism, with the Pco2 level thus held constant, the inflating pressure fell and the average arterial O2 saturation fell 2.8% (20 mm Hg, or a 21% fall). These results have been interpreted to reflect the influence of N2O excretion upon both alveolar O2 and CO2.

Submitted on February 6, 1961
Diffusion and solubility factors in pulmonary inert gas exchanges
Authors: Chinard Francis P. , Enns Theodore , Nolan Mary F.
Published: December 2017

Comparisons have been made in anesthetized dogs of the relative recoveries in arterial blood of pairs of inert gases injected as solutions into the right heart or as gas mixtures into the trachea. The gases differed in their diffusion coefficients or in their solubility. The pairs used were: tritium and Kr85; ethylene-C14 and Xe133. The ratios of the recoveries of the gases approached the ratios of their solubilities and not the ratios of their diffusion coefficients. The site of injection had no significant effect. The concentration-time curves remain proportional during the first passage through the lungs. Diffusion equilibrium is attained within the time of passage of blood through the alveolar capillary. There is no evidence of a diffusion limitation on the exchange of gases with diffusion coefficients as small as that of xenon. Solubility is the limiting factor.

Submitted on April 12, 1961
Acid-base changes in blood and cerebrospinal fluid during altered ventilation
Authors: Merwarth C. R. , Sieker H. O.
Published: December 2017

Functional abnormalities of the central nervous system are observed with hypo- and hyperventilation. This study correlates changes of pH, carbon dioxide tension and carbon dioxide content in arterial and cerebral venous blood and cerebrospinal fluid during altered ventilation. With the experimental design in which ventilation was controlled and the sagittal sinus, femoral artery, and cisterna magna were cannulated, a slight metabolic acidosis was found. With 10% CO2 inhalation acidosis occurred in both blood and spinal fluid and early in the period of inhalation, the usual cerebrospinal-arterial fluid pCO2 gradient was reversed. With hyperventilation, pH and pCO2 changes were more pronounced in the arterial blood but, as hyperventilation was continued, the arterial-cerebrospinal fluid difference decreased. It appeared likely that brain tissue acts as an important buffer, absorbing and releasing CO2 during states of altered ventilation. CO2 diffuses rapidly across cell boundaries, whereas bicarbonate crosses more slowly, thus providing an explanation for the differences noted between blood and cerebrospinal fluid. The particular clinical importance of these observations is that arterial pH, pCO2, and CO2 content may not accurately reflect changes within the cerebrospinal fluid or brain when ventilation is altered.

Submitted on May 1, 1961
Carbon dioxide transport in anesthetized dogs during inhibition of carbonic anhydrase
Authors: Cain Stephen M. , Otis Arthur B.
Published: December 2017

Following inhibition of blood carbonic anhydrase by acetazolamide in anesthetized dogs with one lung rebreathing in connection with a bag and with the other lung ventilating freely on pure oxygen, mixed venous Pco2 increased and alveolar Pco2 decreased. Carbon dioxide output dropped initially but gradually rose and attained a steady state value equal to that of the initial control condition. Before acetazolamide, 19% of the pulmonary CO22 output was derived from dissolved CO2, 26% from carbamino compound, and 55% from bicarbonate. In the new steady state following acetazolamide, 45% came from dissolved CO2, 38% from carbamino, and 17% from bicarbonate.

Submitted on June 12, 1961
Transition between laminar and turbulent flow in human trachea
Authors: Dekker E.
Published: December 2017

The critical velocities at which turbulence appears were determined, during the flow of both water and air, in 21 transparent plastic casts of human tracheae. The flow patterns varied considerably in casts from different individuals. The critical flow velocity of air moving through tracheal casts without the larynx averaged about 350 ml of air per second. In tracheal casts including the larynx, with the glottis in cadaveric position, the critical inspiratory flow was about 50 ml of air per second. With the glottis opened into a more natural position, the critical inspiratory flow velocity was higher, about 100 ml of air per second. The mean value of the critical expiratory flow was 122 ml of air per second. Air flow in the trachea of most individuals is probably turbulent during the greater part of normal respiratory activity. Calculation of critical flow velocities in the airways by means of Reynolds' formula for smooth cylindrical tubes leads to erroneously high values.

Submitted on April 24, 1961
Cardiorespiratory responses during prolonged exercise
Authors: Michael Ernest D. , Hutton Kenneth E. , Horvath Steven M.
Published: December 2017

Three healthy male subjects 20 years of age were exercised for 2—8 hr riding a bicycle ergometer or walking on a treadmill. Higher heart rates were found with the bicycle rides than with the walking exercises with equivalent oxygen uptakes. The subjects could not work on the bicycle ergometer at oxygen uptakes of 1.8 liters/min for more than 4 hr but could with this uptake walk 8 hr. The results indicated that an 8-hr period of exercise could be completed without undue fatigue whenever the energy cost did not exceed 35% of the maximum oxygen uptake where heart rates, oxygen uptakes, and rectal temperatures remained below 120 beats/min, 1.4 liters/min, and 38 C, respectively. The heart rate appeared to be the important factor for estimating 8-hr work endurance. A rate of 140 beats/min could not be maintained for more than 4 hr or a rate of 160 beats/min for more than 2 hr without extreme fatigue.

Submitted on October 26, 1960
Mechanical work of breathing during exercise in trained and untrained subjects
Authors: Milic-Emili G. , Petit J. M. , Deroanne R.
Published: December 2017

The mechanical work of breathing was measured from simultaneous records of esophageal pressure and tidal volume on seven well trained and seven untrained subjects exercising on a bicycle ergometer. At any given value of pulmonary ventilation, mechanical work of breathing was found to be the same for untrained and trained subjects. At any given value of oxygen uptake, pulmonary ventilation and, accordingly, mechanical work of breathing were found to be smaller in trained than in untrained individuals.

Submitted on June 9, 1961
Characteristics of pressure-flow regulation by the kidney
Authors: Schmid Herman E. , Spencer Merrill P.
Published: December 2017

Pressure-flow relationships in the dog kidney were studied by means of a square wave, noncannulating electromagnetic flowmeter probe placed around the renal artery by way of a retroperitoneal approach. Renal artery pressure was varied by a clamp on the artery and recorded via a needle inserted distal to the probe and clamp. Reductions in artery pressure from control levels demonstrated complete regulation of flow from control level down to 70 mm Hg, incomplete regulation from 50–70 mm Hg, and inability to compensate further below 50 mm Hg. Insignificant regulation was found in the iliac vascular bed by this technique. Recovery time of flow occurred within 5–60 sec following occlusion and was more prolonged at lower levels of artery pressure. The findings of a sharp inflection in the pressure-flow plot at approximately 70 mm Hg and a time course of regulation and recovery pattern varying with the reduced artery pressure suggest an active mechanism controlled by a sensitive feedback system.

Submitted on September 18, 1961
Diaphragm activity and thoracoabdominal mechanics during positive pressure breathing
Authors: Agostoni Emilio
Published: December 2017

The electrical activity of the diaphragm and the mechanical contribution of the thorax and the abdomen through the breathing cycle has been investigated in man during positive pressure breathing (PPB). The electrical activity of the diaphragm persists even at values at which inspiration should be completely passive according to the pressure volume diagram of the thorax and lung. The transdiaphragmatic pressure decreases as the value of PPB increases but is still appreciable at values of PPB at which the inspiration appears to be completely passive by an analysis based on transthoracic pressure measurements alone; the transdiaphragmatic pressure becomes zero only at PPB of about 30 cm H2O. The persistent activity of the diaphragm during PPB is counterbalanced by an activity of the abdominal muscles in excess of that of the expiratory muscles as given by transthoracic pressure measurements. Owing to the persistence of an abdominothoracic pressure gradient, the venous return and therefore the cardiac output should be less reduced than in the case of a passive inspiration.

Submitted on September 22, 1961
Breath holding at beginning of exercise
Authors: Cummings E. G.
Published: December 2017

Men stood astride a moving treadmill belt and at a verbal signal held their breath, jumped on the treadmill belt, and walked or ran at a series of speeds up to 9 mph until the breaking point was reached. Breath-holding time decreased sharply with increasing exercise rates, but began to level off at approximately 30 sec between 6 and 9 mph. Breaking-point alveolar Po2 decreased and Pco2 increased with increasing treadmill speeds. When these two factors were applied in the Otis, Fenn, and Rahn ventilation equation to describe ventilation at the breaking point, the ventilation ratio increased, and it was observed that the men withstood a stronger stimulus to breathe as the work rate increased, even though the breath-holding time remained fairly constant at higher work levels. Apparently at the beginning of work the stimulus to breathe is the combination of a relatively weak neurogenic stimulus and an accumulating chemical stimulus. It is postulated that the constancy of beginning breath-holding times at high work rates may reflect a transport time for the chemical stimulus to reach the receptor area from working muscles via the circulation.

Submitted on September 25, 1961
Evaluation of iron stores as limiting high altitude polycythemia
Authors: Hornbein Thomas F.
Published: December 2017

The total amount of iron available from normal body stores and usual dietary intake might be so small as to limit the rate and magnitude of the polycythemic response to high altitude. To evaluate this problem the influence of iron supplementation on blood hemoglobin concentrations was observed in ten members of a Himalayan expedition during the course of their ascent of a 25,660-ft peak. Half the group received iron supplements in large doses both orally and parenterally; the other five obtained only the iron present in the normal high altitude diet. Hemoglobin concentrations in both groups increased by 33% over 2 months. No significant difference in hemoglobin concentrations between the two groups was noted at any time during the course of the study. It is concluded that normal iron stores plus dietary iron were adequate to meet the needs of increased hemoglobin synthesis at high altitude in the five individuals who received no iron supplementation.

Submitted on July 31, 1961
Physical regulation of temperature in Eskimos
Authors: Rennie Donald W. , Covino Benjamin G. , Blair Murray R. , Rodahl K.
Published: December 2017

Temperature regulation of Eskimos and non-Eskimos, exclusive of shivering, was compared over a range of controlled conditions that produced near-maximal sweating (room temp., 35 C) to maximal cutaneous vasoconstriction (23 C air or 33 C water bath). The Eskimos consistently produced 15-20 kcal/m2/hr more heat at rest. This may or may not be cold adaptation. In air warmer than 28 C their surfeit of heat resulted in higher tissue conductances, warmer skin, and greater sweating. In cooler air and 33 C water, the physical conductance of heat through tissues of the Eskimos remained 60% greater and resulted in warmer skin or a greater fall of rectal temperature. This can be accounted for on physical grounds, since the Eskimos had 1 cm less subcutaneous fat than did non-Eskimos. The value of high metabolism and high tissue conductance to fully clothed Eskimos would appear to be reflex vascular convection of heat to distal extremities, since average skin temperatures under their clothing are comparable to those of unclothed Eskimos in room temperatures exceeding 28 C.

Submitted on August 17, 1961
Postural variations in dead space and CO2 gradients breathing air and O2
Authors: Larson C. P. , Severinghaus J. W.
Published: December 2017

Effects of postural changes on anatomic and physiologic dead space and arterial-alveolar CO2gradients were studied in 11 healthy, adult subjects breathing air and O2. Results indicate that, on moving from the supine to the sitting position, Vads and Vpds increased by corresponding amounts (42 and 37 ml) with no increase in alveolar dead space or volume of lung which is nonperfused. Arterial-alveolar CO2 gradients were unaffected by posture, but more than doubled with O2 breathing, suggesting that O2 may relax the pulmonary vascular bed and diminish perfusion of highest lung segments. Isoproterenol aerosol (0.5%) produced significant bronchodilatation (27 ml increase in Vads), but only small and inconsistent increases in alveolar dead space and CO2 gradients. The PDS/Vt ratio in these subjects while sitting, breathing air, averaged 31 ± 6%, which is higher than the normally accepted value of 30%. As a result, the upper normal limit for PDS/Vt has been increased to 40% in our laboratories.

Submitted on January 22, 1962
Cold vasodilatation and cold acclimatization in the hands of British fish filleters
Authors: Nelms J. D. , Soper D. J. G.
Published: December 2017

The duration of vasoconstriction and magnitude of cold vasodilatation of 11 experienced fish filleters was compared with 9 controls by immersion of the left hand in stirred ice and water mixtures. Vasodilatation occurred significantly earlier in the filleters, whose hand skin temperatures were significantly higher during immersion, in both the initial vasoconstriction and after vasodilatation. Results similar in some respects were obtained by immersion of the hands in water initially at 5 C. Several of the controls fainted and all were distressed, whereas most of the filleters were unaffected by the cold water. The difference is considered to show the characteristics of acclimatization, and the fact that the filleters are accustomed to working with their hands in very cold water is considered to be the stress producing the acclimatization response.

Submitted on July 31, 1961
Relation of geometry to certain aspects of hydrodynamics in larger pulmonary arteries
Authors: Fry Donald L. , Patel Dali J. , De Freitas Flavio M.
Published: December 2017

Pressure-flow relationships in the major pulmonary artery of the dog associated with accelerations imposed on flow by the geometry of vessel walls were evaluated. Assuming irrotational flow, the pressure-flow relationships may be evaluated by numerical substitution of fluid boundary measurements into Bernoulli's equation. Fluid boundary dimensions were obtained from Jeltrate casts of the pulmonary arterial tree in eight dogs. The results indicate that significant pressure differences may occur in the pulmonary artery at peak systolic blood flows due to nonuniformity and curvature of these vessels.

Submitted on December 4, 1961
Responses to exercise as related to age and environmental temperature
Authors: Dill D. B. , Consolazio C. F.
Published: December 2017

The responses of two subjects to exercise were studied after a time lapse of 29 years. Environmental temperatures varied from 0 to 50 C and oxygen consumptions from the resting value to about ten times basal metabolic rate. In DBD, present age 70, the heart rates were about the same in easy and moderate work at temperatures up to 40 C but much higher at 50 C. In FC, present age 50, at all work levels the heart rates were the same up to 20 C, lower at 30 and 40 C, and higher at 50 C. The aerobic capacity of both subjects had declined about one-fourth. Thus the responses to the stress of extreme heat showed little loss, whereas there was considerable loss in the ability to withstand the stress of hard work

Submitted on February 19, 1962
Changes in blood gases and acid-base balance in the exercising dog
Authors: Wathen Ronald L. , Rostorfer Howard H. , Robinson Sid , Newton Jerry L. , Bailie Michael D.
Published: December 2017

Effects of varying rates of treadmill work on blood gases and hydrogen ion concentrations of four healthy young dogs were determined by analyses of blood for O2 and CO2 contents, Po2, Pco2, and pH. Changes in these parameters were also observed during 30-min recovery periods from hard work. Arterial and mixed venous blood samples were obtained simultaneously during work through a polyethylene catheter in the right ventricle and an indwelling needle in an exteriorized carotid artery. Mixed venous O2 content, Po2 and O2 saturation fell with increased work, whereas arterial values showed little or no change. Mixed venous CO2 content, Pco2, and hydrogen ion concentration exhibited little change from resting levels in two dogs but increased significantly in two others during exercise. These values always decreased in the arterial blood during exercise, indicating the presence of respiratory alkalosis. On cessation of exercise, hyperventilation increased the degree of respiratory alkalosis, causing it to be reflected on the venous side of the circulation.

Submitted on January 8, 1962
Blood flow in arm and finger during muscle contraction and joint position changes
Authors: Rohter Frank D. , Hyman Chester
Published: December 2017

Digital pulse and blood flow were measured while subjects squeezed a hand dynamom eter. The pulse wave was obliterated at 25% maximum hand grip, and blood flow was occluded at 45% maximum hand grip. Maximum hand grip did not reduce radial pulse, therefore occlusion occurred at some point distal to the forearm muscles. Changes in blood flow suggest that the superficial palmar arch is occluded first and subsequently the deep palmar arch is arrested. Strong contraction of the biceps abolished the radial pulse, but did not diminish the brachial pulse wave; therefore occlusion must occur between the upper arm and the wrist, probably immediately distal to the elbow where the artery proceeds under the fascia of the biceps. Contracting the pronator teres also obliterated the digital pulse wave. Finally, it is possible to eliminate the digital pulse by rotating the clavicle backward, pressing the artery against the first rib. This was accomplished by horizontal retraction of the upper arm while it was elevated laterally or by simply jamming back the forward and horizontally elevated extremity.

Submitted on February 20, 1961
Concurrent measurements of functional residual capacity by three methods
Authors: Tierney Donald F. , Nadel Jay A.
Published: December 2017

We made concurrent measurements of the functional residual capacity (FRC) with the body plethysmograph (thoracic gas volume) and by 7-min and prolonged open-circuit nitrogen dilution methods (communicating gas volume). The mean difference between the 7-min communicating gas volume and the thoracic gas volume in 13 healthy subjects was only 0.13 liters. The thoracic gas volume averaged 0.99 liters larger than the communicating gas volume after 7 min of O2 breathing in 13 patients with emphysema. The communicating gas volume at 12–18 min was the same as the thoracic gas volume in 11 of 13 patients but was smaller in the other 2. When the thoracic gas volume was used to measure FRC, the total lung capacity averaged 142% of predicted normal in 13 patients with emphysema.

Submitted on January 4, 1962
Influence of carbon dioxide and hyperventilation on cardiac output in man
Authors: McGregor M. , Donevan R. E. , Anderson N. M.
Published: December 2017

The effect of changes in ventilation and carbon dioxide tension on cardiac output was studied in seven normal human subjects in the supine posture using a dye dilution method. Voluntary hyperventilation of room air with resultant hypocapnia invariably produced an increase in cardiac output (mean, 38 ml blood/ liter increase in ventilation). Voluntary hyperventilation with maintenance of CO2 tension at near normal levels resulted in a smaller increase in cardiac output (mean, 15 ml/liter). Hyperventilation produced by the inhalation of 8.4% CO2 produced no change in cardiac output within the first 2 min but an increase thereafter. The response of the cardiac output to hyperventilation is thus largely determined by the carbon dioxide content of the inspirate. The manner in which this takes place is uncertain. The higher cardiac output response at 2 min with hypocapnia may be partly the result of respiratory alkalosis. It might also be related to the increase in respiratory mechanical work per liter ventilation associated with the fall in CO2. The reason for the late rise of cardiac output with hypercapnia is unknown.

Submitted on May 14, 1962
Some effects of apneic underwater diving on blood gases, lactate, and pressure in man
Authors: Olsen C. Robert , Fanestil Darrell D. , Scholander Per F.
Published: December 2017

Five men of outstanding diving ability performed apneic underwater dives in a specially fitted tank. The divers hyperventilated to extreme degrees of hypocapnia before submerging, and their arterial blood carbon dioxide tensions rarely rose above normal levels during a dive. Arterial blood oxygen content was 15.5 vol % or above at the end of two 3-min resting dives and of three 1.5-min exercise dives. Blood lactate concentrations increased during the latter half of exercise dives and reached peak values after surfacing. A rise in arterial blood pressure began by 10 sec in each dive and persisted, coincident with a falling heart rate, to the end of the dive. The rate of blood pressure rise was greater during a dive in water of 26 C than with breath holding by the same subject out of water. Some differences between the adaptations of diving men and of other diving mammals are briefly discussed.

Submitted on April 2, 196
Physical insulation of Korean diving women
Authors: Rennie D. W. , Covino B. G. , Howell B. J. , Song S. H. , Kang B. S. , Hong S. K.
Published: December 2017

Human cold adaptation was studied by comparing maximal body insulation [ I = (rectal temp. – skin temp.) /rate of skin heat loss] of Korean diving women to insulation of Korean nondiving men and women and American men and women. Appropriate measurements were made during immersion in a constant-temperature bath cool enough to induce maximal cutaneous vasoconstriction without shivering. Subcutaneous fat was estimated from measurements of skin-fold thickness. Within each racial group there is a significant regression of I on fat thickness. Koreans had a significantly greater I than Americans of comparable fat thickness. Korean diving women had the same I as nondivers of comparable fat thickness. Korean women had significantly greater I than Korean men due, we believe, to thicker subcutaneous fat. This may be the reason why women and not men engage in diving. The only evidence for cold adaptation among diving women was their ability to withstand colder water immersion without shivering.

Submitted on March 22, 1962
Effect of serum albumin infusion on lipid mobilization in man
Authors: Bogdonoff Morton D. , Linhart Joseph W. , Estes E. Harvey
Published: December 2017

Serial plasma free fatty acid (FFA), cholesterol, and triglyceride levels were measured in 5 normal human subjects and in 11 hypoalbuminemic patients after infusion of norepinephrine with and without prior infusion of 50 g of serum albumin. In the hypoalbuminemic patients the peak response in FFA level to norepinephrine was diminished; after albumin infusion the peak rise of FFA level to norepinephrine was enhanced in both the normal and hypoalbuminemic individuals. Alterations in serum triglyceride and cholesterol concentrations that followed albumin infusion could be accounted for by the alteration in plasma volume that also occurred. The diminished FFA response in hypoalbuminemic patients was interpreted as indicating that norepinephrine-induced fat mobilization in man is dependent on the concentration of serum albumin, and that the defect in fat mobilization in hypoalbuminemia may be, in part, related to the alterations in cholesterol and triglyceride metabolism that are characteristic of hypoalbuminemia.

Submitted on April 20, 1962
Pulmonary capillary blood volume in dog: effects of 5-hydroxytryptamine
Authors: Young Roscoe C. , Nagano Hitoshi , Vaughan Thomas R. , Staub Norman C.
Published: December 2017

We studied changes in pulmonary capillary blood volume (Vc) in anesthetized dogs to determine whether 5-HT (5-hydroxytryptamine) constricts pulmonary venules. The preparation was sufficiently stable to allow reproducible measurement of pulmonary diffusing capacity (Dl). A fixed volume of CO gas mixture was introduced into the lungs by positive pressure, and an alveolar sample was obtained after 10 sec. By measuring Dl at different levels of Pao2, a value proportional to Vc was obtained. We cannot give absolute values for Vc since the rate at which CO replaces O2 in red cells in dogs is unknown. In 10 of 14 dogs given 5-HT, Vc increased 6 to 133%. There were no differences in left ventricular diastolic, systemic arterial, or airway pressures. Changes in blood flow were unrelated to changes in Vc. These findings are independent evidence that 5-HT causes pulmonary venous constriction, which in turn leads to passive congestion of the pulmonary capillary bed.

Submitted on July 5, 1962
Diving pattern, lung volumes, and alveolar gas of the Korean diving woman (ama)
Authors: Hong S. K. , Rahn H. , Kang D. H. , Song S. H. , Kang B. S.
Published: December 2017

Lung volumes and alveolar gases during actual dives were studied in the Korean diving women, or ama. These women dive without assistance. Average descent and ascent velocities are 0.6 m/sec. Maximal depth and duration of dive observed were 17 m and 82 sec, respectively. However, typical sustained diving activity is to a depth of 5 m for 30 sec, averaging 60 dives/hr. This diving pattern is compared with the assisted dives of the Japanese ama lasting 60 sec and reaching a depth of about 20 m. Prior to diving the lung is filled to 85% of vital capacity. About 700 ml of this gas are lost upon return to the surface. A slight hyperventilation before dive reduces the Pco2 to 28. At the bottom the fractional composition of O2 as well as CO2 is less than before dive indicating that both gases are removed by the circulation. The compression of the gases accounts for the reversal of CO2 transport. Upon return to the surface CO2 leaves the blood and reaches normal values while the O2 is very low. At the bottom O2 pressure is high due to compression but falls rapidly upon ascent. The detailed pattern of gas exchange is discussed.

Submitted on September 28, 1962
Effects of continuous administration of angiotensin II on ventricular performance
Authors: Downing S. Evans , Sonnenblick Edmund H.
Published: December 2017

The effects of angiotensin II on circulatory dynamics and coronary blood flow were studied in the cat. With equal single doses of angiotensin II and norepinephrine a greater blood pressure response occurred with angiotensin. With continuous administration of angiotensin II a large initial blood pressure response occurred, but rapidly returned to an intermediate value. During this time the animal was refractory to further single doses. A sustained large increase of ventricular contractility was readily demonstrated with the continuous administration of norepinephrine, but could not be demonstrated with equal amounts of angiotensin II. Acute transient changes of ventricular contractility were observed. Frequently an acute increase of both stroke work at a given filling pressure, and mean rate of ejection occurred. Occasionally, however, marked acute myocardial depression, which rapidly returned to control values, was observed. In about one-third of the preparations prolonged myocardial depression was observed following a period of continuous angiotensin II infusion. This was in sharp contrast to continuous norepinephrine infusion following which myocardial depression was never observed. Measurements of coronary blood flow indicated that when ventricular work was maintained constant, continuous angiotensin II infusion was frequently associated with a transient reduction of coronary flow. This was usually small, but occasionally marked. During this phase concomitant myocardial depression was evident. Continuous norepinephrine infusion produced only an increase of coronary blood flow with an associated increase of myocardial contractility.

Submitted on October 11, 1962
Effect of muscular exercise on plasma viscosity in correlation with postprandial triglyceridemia
Authors: Konttinen Aarne , Somer Timo
Published: December 2017

The correlation between postprandial triglyceridemia and plasma viscosity was studied in 45 healthy young men. One-half, 23, of them carried out a heavy march lasting 2 hr while the other half, 22, rested in bed. Serum triglycerides and plasma viscosity were determined before the fat meal and 4 and 6 hr postprandially. Serum total proteins and hematocrits were measured simultaneously. Despite significantly higher postprandial triglyceridemia in the resting group no rise was seen in plasma viscosity, whereas, in the exercise group with a lower triglyceride level a significant elevation took place in plasma viscosity.

serum triglycerides

Submitted on February 18, 1963
Calcium phosphorus metabolism in man during acclimatization to carbon dioxide
Authors: Schaefer K. E. , Nichols G. , Carey C. R.
Published: December 2017

The calcium phosphorus metabolism was studied in 20 subjects who were exposed for 42 days to 1.5% CO2. Plasma calcium mirrored the changes of the pH, showing a decrease during the first 23 days of exposure, a return to initial levels during the latter part of exposure, a marked rise above control values during the 8–9 day recovery period following exposure, and a return to normal values after 4 weeks of recovery. Changes in plasma calcium were found to correspond to changes in pulmonary CO2 excretion indicating a significant role of bone CO2 stores in acclimatization and deacclimatization of carbon dioxide. Plasma inorganic phosphorus was elevated throughout the exposure period and recovery period. At the end of the exposure period to CO2 red cell calcium had increased and red cell phosphorus had decreased. After 9 days, as well as after 4 weeks, of recovery on air the calcium content of the red cells continued to increase and the inorganic phosphorus values remained lowered.

chronic respiratory acidosis; chronic hypercapnia

Submitted on November 2, 1961
Human cerebral circulation during deliberate hypotension and head-up tilt
Authors: Eckenhoff James E. , Enderby G. E. Hale , Larson Alex , Davies Russell , Judevine Donald E.
Published: December 2017

Forty-two patients for elective surgical procedures were anesthetized with thiopental, nitrous oxide, and halothane and made hypotensive by ganglionic blockade with pentolinium, hexamethonium, trimethaphan, and/or guanethidine, combined with head-up body tilt, with or without positive airway pressure. In 23 patients, the systolic arterial pressure was at or below 70 mm Hg for an average of 42 min. In six patients, the systolic pressure was 50 mm Hg or below for an average of 39 min with an average head-up tilt of 24°. The lowest jugular bulb Po2 recorded during hypotension was 27 mm Hg except in six instances when lower figures were recorded in the presence of increased airway pressure. Jugular bulb Po2 was better correlated with PaCOCO2 (r = 0.79) than with arterial pressure (r = 0.56). In the head-up position, jugular bulb pressures were usually above atmospheric pressure and were related to arterial carbon dioxide tension (r = 0.58). Cerebrovascular compensation appeared adequate under the conditions of deliberate hypotension as produced with this technique.

hypotension during anesthesia; hypercapnia during hypotension; cerebral venous pressures; pulse waves

Submitted on March 4, 1963
Regulation of breathing at beginning of exercise
Authors: Craig F. N. , Cummings E. G. , Blevins W. V.
Published: December 2017

In initial 20-sec periods of running on the treadmill, raising the slope to 12% increased by 50% the integrated muscle action potential, recorded from the under side of the thigh, without affecting the ventilation in four men. Five men worked for 1 min at four tasks, two on the treadmill and two on the horizontal cycle ergometer. Each pair of tasks consisted of slow and rapid leg movement at the same rate of work. Ventilation often continued at about the resting rate for the first few seconds of work, unaffected in any significant way by frequency of leg movement. In the subject responding to the onset of exercise by a sudden sharp involuntary increase in ventilation, the nature of the nervous respiratory drive is not clear. Whatever drive arises from the work itself may be strongly modified by training or by complexities in the work situation.

leg movement; muscle action potential; nervous respiratory drive

Submitted on May 16, 1963
Circulation in exercising dogs
Authors: Cerretelli P. , Piiper J. , Mangili F. , Cuttica F. , Ricci B.
Published: December 2017

The adjustments of the cardiovascular system to muscular exercise were studied in dogs running on a treadmill at different speeds and at the incline of +10%. The cardiac output, measured by the thermodilution method, increased with increasing O2 consumption, reaching 520 ml/kg min at an O2 consumption of 70 ml/kg min. At still higher metabolic levels the cardiac output remained constant and the O2 consumption increased by an increase of the arteriovenous O2 difference only, which was calculated to attain 17 vol % at the highest O2 consumption value reached in this study, 90 ml/kg min. The increase of the cardiac output was mainly due to increase of the heart rate, whereas the average maximum increment of the stroke volume was about 30% only. The mean arterial and the central venous blood pressures increased with exercise. The time course of the adjustment of the cardiac output was measured after the exercise of varied intensity had been abruptly begun or stopped. Both for start and recovery the “half reaction time” was about 20 sec; after 1 min no further measurable change of the cardiac output was detectable.

cardiac output and O2 consumption at increasing metabolic levels; heart rate and stroke volume in running dogs recovery following exercise

Submitted on July 15, 1963
Thermal balance and biogenic amine excretion in Gaspé fishermen exposed to cold
Authors: Leblanc Jacques , Pouliot M. , Rheaume S.
Published: December 2017

Previous studies have shown a decreased response in fishermen to cold applied locally. In the present study, the same subjects, when exposed naked for 1 hr at 60 F maintained a higher skin temperature than a control group. If these findings indicate a decreased vasoconstriction, all results obtained to date on these fishermen would indicate a decreased adrenergic response. Evidence of gross shivering was much more pronounced in the fishermen but this was not reflected by greater heat production. Both groups excreted more hydroxycortisone in the cold, and the excretion was higher in the control subjects. Cold exposure did not increase the catecholamine excretion in either group.

Note:

(With the Technical Assistance of P. Tousignant)

acclimatization; body temperature; skin temperature; vasomotor adaptation; shivering; adrenergic response in cold habituation; hydroxycortisone excretion in cold stress

Submitted on June 17, 1963
Maximum ventilatory performance and its limiting factors
Authors: Shapiro William , Johnston C. E. , Dameron R. A. , Patterson J. L.
Published: December 2017

Pressure-volume-flow relationships during maximum-effort expirations and inspirations were analyzed in 27 studies on 7 superbly conditioned nonsmoking athletes, 5 nonathletic nonsmokers, and 7 nonathletic smokers. The athletes had larger mean vital capacity and maximum breathing capacity as well as higher airflow during the first half of forced inspiration than the other subjects. In contrast, smokers exhibited lower mean vital capacity, lower air flows, and higher transpulmonary pressures during forced expirations than the nonsmokers. Transpulmonary pressures at peak flow during maximal forced expirations were higher in the present study than those commonly reported and may have been due to the technique used to perform this maneuver. Limiting factors apparently operate to prevent superior athletic conditioning from effecting comparable improvement in ventilatory performance. The favorable alterations in this performance which were observed in the athletes do not seem sufficient to explain their greater endurance. Mild decreases in ventilatory performance were exhibited by the smokers, probably due to the chronic effects of cigarette smoking on the pulmonary airways.

respiratory pressure-volume-flow relationships; vital capacity and maximum breathing capacity in athletes; esophageal balloon system for measuring transpulmonary pressure

Submitted on April 25, 1963
Respiratory thoraco-abdominal mechanics in man
Authors: Milic-Emili Joseph , Orzalesi Marcello M. , Cook Charles D. , Turner James M.
Published: December 2017

The behavior of the diaphragm and the thoracic and abdominal muscles during various static and dynamic respiratory maneuvers was studied in six trained men by measuring intrathoracic (esophageal) and intra-abdominal (gastric) pressures together with lung volumes. The static maneuvers included voluntary relaxation of respiratory muscles, maximal inspiratory and expiratory efforts, and maximal abdominal expulsive efforts. The dynamic maneuvers were forced inspiratory and expiratory vital capacities and maximal voluntary ventilation. The patterns during the various respiratory maneuvers were relatively uniform. Although the number of subjects studied was small, our results would appear to give a general description of thoraco-abdominal mechanics, at least in trained subjects.

breathing patterns; static respiratory maneuvers; maximal voluntary ventilation; forced inspiration and expiration; dynamic respiratory maneuvers; abdominal pressures and thoracic pressures at varying lung volumes

Submitted on May 13, 1963