bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of increased static lung recoil on bronchial dimesions of excised lungs
Authors: Hyatt R. E. , Rodarte J. R. , Wilson T. A.
Published: December 2017

We measured bronchial diameters and lengths during static deflation and inflation in eight excised dog lobes before and after static lung recoil (Pst(L)) had been significantly increased by cooling the lobe for 48 h at 4 degrees C and ventilating it for 3 h. In control lobes, bronchial diameters were the same at any volume even though Pst(L) was different during inflation and deflation. These results agree with those of Hughes et al. (J. Appl. Physiol. 32: 25–35, 1972). However, when Pst(L) was increased, diameters at a given volume were significantly increased over control values; diameters at a given pressure were nearly the same as the controls. Therefore, under these conditions, bronchial diameter did not conform to lung volume. The ventilation process appeared to alter the circumferential elastic properties of the bronchi because diameters at all pressures were slightly larger after ventilation. Bronchial length-volume relationships were the same in both control and ventilated lobes. Thus, when Pst(L) was markedly increased, diameter corresponded best to lung recoil and length to lung volume.
Stability in lobar ventilation distribution during change in thoracic configuration
Authors: Minh V. D. , Dolan G. F. , Kurihara N. , Friedman P. J. , Konopka R. G. , Moser K. M.
Published: December 2017

Stability in lobar ventilation was examined in dogs during bilateral electrophrenic respiration (BEPR) and positive pressure-assisted ventilation (PPAV). Bilateral prior ligation of the lower and middle lobe pulmonary arteries monitoring of upper lobe ventilation as alveolar minute ventilation (VA), middle and lower lobe ventilation as dead space (VD), and VD/VT ratio, both calculated by the Bohr equation. As documented by chest films, transverse and anteroposterior thoracic diameters during BEPR decreased below FRC values whereas thoracic cephalocaudal dimension greatly increased. During PPAV, all thoracic dimensions increased. Despite these dissimilar regional chest movements, VA, VD, and VD/VT ratio were comparable between PPAV and BEPR under conditions of matched tidal volume and respiratory frequency. Stability in upper lobe ventilation during BEPR was maintained by caudal displacement despite the compression of the rib cage, as documented by tantalum bronchography. Lobar-interdependence appears to be the mechanism transmitting negative pleural pressure developed by the diaphragm to the upper lobes via lower and middle lobe inflation.
Effect of altitude relocations upon AaDo2 at rest and during exercise
Authors: Cruz J. C. , Hartley L. H. , Vogel J. A.
Published: December 2017

The supine pulmonary venous admixture (shunt) has been measured at Cerro de Pasco, 4,350 m altitude in eight subjects native to high altitude (HAN) under resting condition. Alveolar-arterial O2 tension difference (AaDO2) was also determined at rest and during exercise. The same subjects were studied again after 10 days' sojourn at sea level in Lima at 150 m altitude. They were compared with four subjects from sea level (SLN) who were studied first at Lima and after 2 and 10 days at Cerro de Pasco. At altitude, AaDO2 was smaller in HAN than SLN both at rest and during exercise. Shunt was the same in both groups. It is concluded that HAN show more even ventilation/perfusion relationship (VA/Q) at altitude, probably due to their high pulmonary artery pressure. On the contrary, SLN show less even VA/Q on altitude exposure, since their shunt decreased 37%. At sea level, HAN increased their AaDO2 due partially to an increase of 110% in their shunt, and in part due to less even VA/Q as shown by augmented VD/VT ratios. Each group tended to have a more effective gas exchange in its own environment.
Effect of prostaglandin E2 on esophageal motility in man
Authors: Mukhopadhyay A. , Rattan S. , Goyal R. K.
Published: December 2017

Studies were performed to investigate the effect of prostaglandin E2 on esophageal motility in 12 healthy volunteers. PGE2 infusion caused a dose-dependent reduction in the lower esophageal sphincter pressure. The threshold dose was less than 0.05 mug-kg-1-min-1 and maximal reduction of pressure (60%) occurred with a dose of 0.4 mug-kg-1-min-1. In contrast to its effect on the lower esophageal sphincter, PGE2 did not alter the pressure in the upper esophageal sphincter. PGE2 did not influence resting esophageal pressures; the amplitude of peristaltic contractions was reduced in the lower but not in the upper part of the body of the esophagus. These studies show that in man PGE2 exerts selective inhibitory influence on the activity of the lower part of the esophagus and lower esophageal sphincter which are composed of smooth muscle fibers.
Changes in the single-breath nitrogen washout curve on exposure to 17,600 ft
Authors: Gray G. W. , McFadden D. M. , Houston C. S. , Bryan A. C.
Published: December 2017

Seventeen volunteers were exposed to 17,600 ft after an acclimatization period, at 9,800 ft. Single-breath nitrogen washout curves were done at base camp (2,600 ft), on days 2 and 4 at 9,800 ft, and on days 1, 2,3 4, and 7 at 17,600 ft. There was a significant 39% increase in the slope of phase III on day 2 at 9,800 ft, accompanied by a 125 ml mean increase in anatomic dead space (Vd) and a marked decrease in cardiac oscillations. By day 4 at 9,800 ft phase III slopes were reduced and were not significantly different from base-line controls, while cardiac oscillations were increased and Vd decreased from day 2. Subsequent exposure to 17,600 ft produced another significant increase in phase III slope to 87% above control, which by day 7 had decreased significantly to 63% above control. Cardiac oscillations were again diminished and Vd increased. These changes cannot be accounted for by changes in gas density, nor by the decrease in PIOO2 per se, since this alone would decrease the range of PaNN2. They suggest a pathophysiologic lung lesion which impairs gas mixing and increases asynchronous emptying during early altitude exposure.

high-altitude pulmonary edema; gas-mixing impairment at altitude

Submitted on November 7, 1974
DC temperature-regulating device for anesthetized experimental animals
Authors: Oberg P. A. , Persson E. , Pettersson H. , Stalbecker S.
Published: December 2017

A temperature-regulating device for anesthetized experimental animals is presented. The rectal temperature of the animal is measured with a thermistor and this variable controls via nonlinear amplification the power fed to the heating pad on which the animal is placed. Rectal temperature variations of not more than +/- 0.1 degrees C are reached after 30 min of operation.
Physiological evidence consistent with the presence of a specific O2 carrier in the placenta
Authors: Gurtner G. , Burns B.
Published: December 2017

In 30 experiments we perfused the fetal side of the sheep placenta with fluids which had different solubilities for argon, N2, and O2 (dextran, blood, and fluorocarbon emulsions). In some of the experiments we partially exchange-transfused the ewe with the fluorocarbon emulsion. By these procedures we were able to change the physical solubility of argon and N2 severalfold in the fetal perfusion fluid and maternal blood. We found that the diffusing capacity for argon and N2 did not increase with increases in physical solubility in the fetal perfusion medium or in maternal blood. This indicated that the rate-limiting step in the placental transfer of these gases is the small diffusing capacity of the placenta. In contrast, O2 diffusing capacity increased markedly with increased solubility in the fetal perfusion medium. Also the Po2 was frequently the same in the venous blood leaving both sides of the placenta. This indicates that O2 may reach equilibrium between maternal and fetal capillaries in one pass through the placenta. The results are compatible with the presence of specific O2 carrier in the placenta.
Thermal responses of unclothed men exposed to both cold temperatures and high altitudes
Authors: Cipriano L. F. , Goldman R. F.
Published: December 2017

Six resting men were exposed to three temperatures (15.5, 21, 26.5 degrees C) for 120 min at three altitudes (sea level, 2,500 m, 5,000 m). A 60-min sea-level control at the scheduled temperature preceded the nine altitude episodes. Comparison of the base-line results at any one temperature showed no differences between rectal temperatures (Tre) or mean weighted skin temperatures (Tsk). After 120 min, Tre and Tsk not only depended on ambient temperature but also altitude. The initial rate of fall in Tre increased with altitude and equilibrium occurred earlier. At 15.5 degrees C, Tre was 0.3 degrees C lower at 5,000 m and 0.2 degrees C lower at 2,500 m than at sea level. Tsk was almost 2 degrees C higher at 15.5 degrees C at 5,000 m and 1 degrees C higher at 2,500 m than at sea level. Similar, smaller differences were observed at 21 degrees C. Mean weighted body temperature showed no change with altitude, but, since the gradient between core and shell was reduced, a shift of blood toward the periphery is implied.
Myocardial infarction in closed-chest dogs: a simplified method for production
Authors: Lappin H. A. , Botvinick E. H. , Parmley W. W. , Tyberg J. V.
Published: December 2017

Due to our need, we sought a simple method to reliably create myocardial infarction in the closed-chest dog. Previous techniques were dangerous, time consuming, unreliable, and costly. Here we described a new coaxial catheter method by which occluded catheter plugs are embolized selectively to branches of the left coronary artery in closed chest dogs anesthetized with sodium pentobarbital (10 mg/lb). Infarcts varying in size from 3 to 27 g, 2–27% of the left ventricle, were reliably created in dogs weighing 26–70 lb. Complications were rare with only a single fatality in the last 15 procedures. The method proved safe, simple, quick, versatile, reproducible, and inexpensive.
Chest wall distortion and regional lung volume distribution in erect humans
Authors: Grassino A. E. , Anthonisen N. R.
Published: December 2017

Using 133Xe measured the regional distribution of FRC and of boluses administered at FRC in seated subjects during relaxation, lateral compression of the lower rib cage, and contraction of the inspiratory muscles so that mouth pressure was 50 cmH2O subatmospheric. Lateral compression increased apex-to-base differences of volume and bolus distribution, suggesting an increase of the apex-to-base gradient of pleural surface pressure. Changes in rib cage shape were measured with magnetometers and were qualitatively similar to those associated with increases in apex-to-base difference of pleural surface pressure in animals. Inspiratory effort decreased apex-to-base difference in volume and induced a similar trend in bolus distribution. Though changes in the rib cage shape were directionally similar, they were much smaller than those associated with decreased pleural surface pressure gradients in animals, and the changes in regional volume we observed were more likely due to forces generated by diaphragmatic contraction. These results were compatible with the apex-to-base gradient of pleural pressure being strongly influenced by shape adaptation between lung and chest wall.
Effect of training on cardiovascular response to exercise in women
Authors: Cunningham D. A. , Hill J. S.
Published: December 2017

Seventeen women (mean age 31 yr) participated in a training program divided into an initial 9-wk period and a subsequent 52-wk period, during which time 6 continued to exercise and the remainder detrained. Improvements in VO2max were significant (+34%) during the initial 9 wk and small (+5%) for the final 52 wk. Four women who stopped training showed a decrease in VO2max (-10%) during the last phase. During the initial 9 wk, central adaptation was important, with SV showing an increase of 28% at 80% VO2max. Peripheral adaptation (a-v O2 difference) was unchanged. Subjects who trained an additional 52 wk showed a slight drop in SV at submaximal work loads from the initial increase following the first 9 wk. When compared with the initial test the change at 9 wk in peripheral adaptation was a small and nonsignificant rise, followed by a significant increase at 61 wk. Women who are very unfit initially (predicted VO2max of 28 ml/kg-min), apparently adapt to the initial training with a central change followed by a much stronger peripheral adaptation during a longer training program.
Effect of exercise and thermal stress on plasma volume
Authors: Harrison M. H. , Edwards R. J. , Leitch D. R.
Published: December 2017

Six male subjects exercised for 50 min at 25% (light exercise) and 55% (moderate exercise) of their estimated aerobic capacities in environments of 42 degrees C db, 35 degrees C wb and 30 degrees C db, 24 degrees C wb, respectively. Alterations in the hematocrit, hemoglobin, and plasma protein concentrations, and in the activity of an injected aliquot of isotopically labeled albumin were each used to calculate the percentage change in plasma volume occurring during exercise and recovery. Changes in each measure were consistent with a reduction in plasma volume during exercise and a return to preexercise levels during recovery. There was no significant difference between the measures when exercising in the heat, but during the more severe exercise in the cooler environment disproportional changes in protein, hematocrit, and hemoglobin were observed. Disproportional changes were also seen during the recovery phase, when the hematocrit and hemoglobin concentration indicated a more rapid return of the plasma volume to preexercise levels than did either the plasma protein concentration or albumin activity. During moderate exercise and recovery there was a 1% decrease in red cell volume. It is concluded that exercise accelerates the rate of protein movement from extravascular compartments to the intravascular compartment, leading to elevated plasma protein levels during recovery which favor the return of water to the intravascular space. Hemoglobin concentration is considered to be the most reliable measure of plasma volume change during exercise.
Tracheal mucous transport in experimental canine asthma
Authors: Wanner A. , Zarzecki S. , Hirsch J. , Epstein S.
Published: December 2017

Tracheal mucous velocity (TMV) was measured in experimental canine asthma. All 10 sensitive dogs exposed to an aerosol of Ascaris suum extract showed a decrease in TMV to about one-third of base-line values within 45 min whereas only half of them (reactors) responded with bronchospasm as measured by a significant reduction in specific respiratory system conductance (SGrs). Mean TMV remained decreased at the end of the 2-h observation period when mean SGrs had returned to base-line values in the reactors. Neither TMV nor SGrs changed in nonsensitive animals who inhaled ragweed antigen. Aerosols of acetylcholine and histamine increased TMV thereby excluding these mediators as responsible for the impairment of mucous transport in asthma. Nebulization of A. suum antigen together with a selective antagonist of slow reacting substance of anaphylaxis (srs-a) produced a marked increase of TMV in all dogs regardless of whether or not bronchospasm was elicited. This suggests that the observed decrease in TMV may be related to the release of SRS-A during the immunologic reaction.
Effect of propranolol on endotoxin-induced pyrogenesis in newborn and adult guinea pigs
Authors: Blatteis C. M.
Published: December 2017

Previous studied have shown that nonshivering thermogenesis (NST) is the prevailing mechanism of fever production in both newborn (during the first 2–3 wk of life) and adult cold-acclimated guinea pigs. This study was undertaken to determine whether this process may be mediated by noradrenergic sympathetics. The temperatures in the interscapular brown fat pad (Tbat) and the colon (Tre), the rate of oxygen consumption (VO2), and shivering activity were measured continuously for 5 h at 27 degrees C ambient temperature in 8- and 16-day-old and adult cold-acclimated guinea pigs following 2 mug/kg iv of Salmonella enteritidis endotoxin, with and without 6.0 mg/kg of propranolol (a beta-adrenergic blocker) injected ip 2 min before the endotoxin. In the older animals, the increase in Tbat normally produced by endotoxin was reduced by propranolol administration, but shivering set in, maintaining both VO2 and Tre at their febrile levels. In the newborn animals, Tbat also was decreased by propranolol, but shivering did not set in, so that VO2 and Tre fell below their febrile values. It is concluded that endotoxin-induced NST is controlled by noradrenergic sympathetics. The failure of NST to be replaced in the present newborn guinea pigs by visible shivering might be related to other observations that the onset of shivering at this age occurs only when Tre is significantly reduced.
Frequency and displacement amplitude relations for normal hand tremor
Authors: Stiles R. N.
Published: December 2017

Spectral analysis of hand tremor records obtained from normal subjects during continuous extension of the hand for 15–45 min revealed that the root-mean-square (rms) displacement amplitude of the tremor increased from control levels of about 30 mum to levels on the order of 100–1,000 times control. Associated with this increase in the displacement was a systematic decrease in the hand tremor frequency from control values of 8–9 Hz to values of 4–6 Hz. Spectral analysis of demodulated extensor EMG records indicated a consistent relation between EMG modulation amplitude at the tremor frequency and the tremor displacement amplitude for tremor records with rms displacement above about 100 mum. No consistent relation was found between these two variables for tremor records with displacements below 100 mum. Consideration of both mechanical and neural reflex effects indicated that a viscoelastic-mass mechanism primarily determined the small-amplitude (less than 100 mum) tremors, while the large displacement tremors may have involved both mechanical and neural feed back factors.
Muscle water and electrolytes following varied levels of dehydration in man
Authors: Costill D. L. , Cote R. , Fink W.
Published: December 2017

In an effort to assess the effects of dehydration on the content of water and electrolytes (Na+, K+, Cl-, and Mg2+) in plasma and muscle tissue, eight men exercised in the heat (39.5 degrees C, 25%). Blood urine, and muscle biopsy samples were obtained before exercise and after the subjects had reduced their body weight by 2.2, 4.1, and 5.8%. On the average, plasma and muscle water (H2Om) contents were found to decline 2.4 and 1.2% for each percent decrease in body weight. Muscle sodium (Na+m) and chloride (Cl-m) content remained unchanged with dehydration, while muscle magnesium (Mg2+m) declined 12% as a result of the 5.8% dehydration. In terms of intracellular concentrations, K+i increased 7.2 and 10.6% at the 2.2 and 4.1% dehydration levels, respectively. Calculations of the resting membrane potential suggest that the water and electrolyte losses observed in these studies do not significantly alter the excitability of the muscle cell membrane.
Sudden interruption of leaflet opening by ventricular contractions: a mechanism of mitral regurgitation
Authors: Tsakiris A. G. , Gordon D. A. , Mathieu Y. , Padiyar R. , Labrosse C.
Published: December 2017

The motion of both mitral cusps and the presence of valvular regurgitation during ventricular contractions were investigated in seven experiments on dogs in which radiopaque markers had been sutured to the cusps and the valve annulus 1–32 wk before the studies. Cineangiograms of the left ventricle were obtained during ventricular ectopic beats, interposed throughout the cardiac cycle (20–99% of cycle length) and during induced variations in the P-R interval (0–200 ms). Mitral regurgitation was observed only during a) weak, early ectopic beats (peak pressure below 34 mmHg) which were incapable of closing the cusps and b) when ventricular contractions suddenly interrupted normal leaflet motion toward the ventricle, during three well-defined periods of diastole (diastolic valve opening, diastolic rebound, and atrial opening). Valve closure following sudden reversal of cusp opening was slow and the leaflets often did not arrive simultaneously at their closed positions. These findings suggest that sudden interruption of leaflet opening by ventricular contractions is an important mechanism of transient mitral regurgitation in the normal heart.
Hypoventilation in ponies after carotid body denervation
Authors: Bisgard G. E. , Forster H. V. , Orr J. A. , Buss D. D. , Rawlings C. A. , Rasmussen B.
Published: December 2017

Seven ponies were subjected to carotid body denervation (CD) and two ponies were sham operated (S). Measurement of arterial blood gases and arterial blood and cerebrospinal fluid (CSF) acid-base balance were made prior to and 1,2,4,9, and 17 wks after surgery in unanesthetized animals. Resting ventilation and ventilatory responsiveness to hypoxia and NaCN infusion were assessed prior to and 2,9, and 17 wks after surgery. Alveolar hypoventilation in the CD ponies was marked 1–2 wk after surgery when VE and VA were reduced 40% and 10%, respectively, from control and PaCO2 was 12–15 mmHg above control. However, the effect was not nearly as great 4, 9, and 17 wk after surgery when the PaCO2 stabilized at approximately 6 mmHg above control PaCO2. Arterial blood pH was normal in the hypercapnic CD ponies, but CSF pH remained acid relative to normal throughout the 17-wk period. Changes in ventilatory responsiveness to hypoxia and NaCN tended to parallel changes in resting ventilation. These findings suggest: 1) the carotid bodies are essential in ponies to maintain normal ventilation: 2) in CD ponies peripheral chemosensitivity is partially regained at some unestablished locus; and 3) pH compensating mechanisms in chronically hypercapnic ponies function relatively better in blood than in CSF.
Effects of water immersion to the neck on pulmonary circulation and tissue volume in man
Authors: Begin R. , Epstein M. , Sackner M. A. , Levinson R. , Dougherty R. , Duncan D.
Published: December 2017

Utilizing the rebreathing of a gas mixture containing C2H2, C180, He O2, and N2, we obtained serial measurements of the pulmonary capillary blood flow (Qc), diffusing capacity per unit of alveolar volume (DL/VA), functional residual capacity (FRC), pulmonary tissue plus capillary blood volume (VTPC), and O2 comsumption (VO2) in five normal subjects under the following conditions: 1) 6 h of sitting, 2) 4 h of sitting while immersed in thermoneutral water to the neck, and 3) 4 h of lying in thermoneutral water to the neck. Water immersion (NI) was preceded and followed by 1-h prestudy and 1-h recovery periods. The measurements were made at 30-min intervals. Seated NI produced a fourfold increase in sodium excretion (UNaV), a 25–36% increase in Qc, a 45–59% increase in DL/VA, and a 30–36% decrease in FRC. This occurred as early as the 1st h of NI and persisted throughout the 4-h period of study. Throughout the seated control and NI periods, VO2, heart rate, and VTPC remained constant. During supine NI, Qc, HR, DL/VA, FRC, and VO2 did not differ significantly from supine prestudy. These date demonstrate that seated NI causes a significant increase of Qc and DL/VA which persists throughout the immersion period. Furthermore, the lack of change of VTPC suggests that the central vascular engorgement induced by seated NI is not accompanied by extravasation of fluid into the pulmonary interstitial space.
Transit time analysis of the forced expiratory spirogram in growth
Authors: Neuburger N. , Levison H. , Bryan A. C. , Kruger K.
Published: December 2017

In the search for more sensitive indicators of airway obstruction Fish et al. (Am. Rev. Respirat. Diseases 109: 700, 1974) have proposed a transit time analysis of the forced expiratory spirogram. In this method the forced vital capacity (FVC) is divided into volumes of air and each volume is assigned a transit time; the nature of the FVC can be described by the transit times' mean, standard deviation, and index of skewness. In a group of 48 healthy nonsmoking subjects between the ages of 9 and 22 yr we found that all three quantities decreased with increasing age. This demonstrates an improvement in the function of the peripheral airways with lung growth. In contrast to the increase in flow rates with lung growth, none of this improved function can be attributed to increased lung volume.
An intercostal-phrenic inhibitory reflex in human newborn infants
Authors: Knill R. , Bryan A. C.
Published: December 2017

An effect of phasic distortion of the rib cage on inspiratory time was studied in thirty sleeping newborn infants. Distortion was produced by both manual compression of various rib cage diameters, and by occluding the airway at functional residual capacity, allowing diaphragmatic contraction to alter rib cage shape. With rapid distortion produced by these maneuvers, inspiration was often terminated prematurely. The effect was dependent upon there being a rapid rate of distortion, and was most readily elicited when inward motion involved the lower lateral rib cage. The results indicate a potent inspiratory inhibitory reflex, originating most probably from the spindles of intercostal muscles. This reflex acts to decrease tidal volume and ventilation when rates of rib cage retraction are high during spontaneous breathing.
Convective and diffusive gas mixing in human lungs: experiments and model analysis
Authors: Sikand R. S. , Magnussen H. , Scheid P. , Piiper J.
Published: December 2017

Equilibration of inspired with lung residual gas was studied by a single-breath technique for varying breath-holding time with He, Ar, and SF6 as test gases. The ratio of end-expired (FE‣) to mean lung concentration after expiration (FL) was always below unity, indicating imperfect mixing of gas in the lung. The ratio of FL/FE‣ for all gases increased with tB, for any tB the ratio was smallest for SF6 and greatest for He. Similarly, Bohr dead space (VD) at any given tB was greatest for SF6 and smallest for He, with VD decreasing toward an asymptotic value common for all gases as tB increased. The results were analyzed quantitatively on a serial three-compartment model of the lung. Model analysis suggests that both diffusion and convection are effective in equilibrating test gases in the lung during breath holding. Further, stratified inhomogeneities in the absence of convective gas mixing in the alveolar space would seriously limit alveolar respiratory gas exchange; with convection, however, stratification is likely to impose only moderate constraints on resting gas exchange.
Transthoracic admittance plethysmograph for measuring cardiac output
Authors: Ito H. , Yamakoshi K. I. , Togawa T.
Published: December 2017

A plethysmograph for measuring ventricular stroke volume (SV) from the transthoracic admittance variation was developed. A correlation study between the SV values determined by this method (SVy) and those measured by Kubicek's transthoracic impedance method (SVz) was carried out on 24 healthy subjects; the correlation coefficient was r = 0.99 and the regression line of SVY on SVz was y = 1.03x - 0.47. Based on the results obtained through the study, it was concluded that the admittance method was more advantageous than the impedance method for measuring SV.
Reusable tubular membrane oxygenator for isolated organ hemoperfusion
Authors: Waugh W. H. , Bales T. E. , Nihei H.
Published: December 2017

A reusable tubular membrane oxygenator is described for hypotraumatic hemoperfusion of isolated organs in physiological studies. The constructed oxygenator was of approximately 0.24-m2 effective surface area and contained 450 silicone rubber capillaries of 0.51-mm nominal ID, 34.9 cm long, fixed by conical-shaped, plastic blood headers at manifolds made from Dow-Corning MDX-4–4210 silicone elastomer. During ex vivo hemoperfusions in dogs at inlet hemoglobin saturations near 67%, oxygen transfer rates of the oxygenator increased serially, from 16.6 +/- 1.7 ml/min per m2 (mean +/- SD) at blood flows of 100 ml/min to 34.1 +/- 3.8 ml/min per m2 at flows of 500 ml/min. The oxygenator was thromboresistant and of much loss priming blood volume and wall compliance than the nonresuable Travenol membrane oxygenator of 0.26-m2 effective surface area. The tubular oxygenator was easily cleaned and reassembled, with reproducible oxygen transfer rates. It should prove useful for hemoperfusion studies in organs of moderate size, such as the isolated canine kidney, stomach, and pancreas.
Gas exchange in man during combined +Gz acceleration and exercise
Authors: Nunneley S. A.
Published: December 2017

Gravity and acceleration from head to foot (+Gz) handicap gas exchange by shifting blood from thorax to dependent veins and creating a ventilation/perfusion (V/Q) mismatch in the lung. At 1 G leg exercise improves V/Q matching. Gas exchange was measured in six subjects +1, +2, and +3 Gz during rest and two levels of exercise, either unloaded pedaling or 600 kpm/min. The VO2 for pedaling was clearly related to G level, but work efficiency was unaffected. Acceleration lowered resting Pao2 while raising VE/VO2, HR, AaDo2, VD, and VD/VT. Unloaded pedaling returned VE/VO2 and HR toward their 1-G values. In contrast, at 3 G each increase in VO2 caused a fall in Pao2 and a rise in AaDo2. The VD showed no further change with exercise, while VD/VT decreased at all G levels. It thus appears that only some of the effects of acceleration are counteracted by exercise, probably by the peripheral muscle pump. Any accompanying rise in VO2 adds to the stress of acceleration, due to limitations on gas transport.
Contribution of gular flutter to evaporative cooling in Japanese quail
Authors: Weathers W. W. , Schoenbaechler D. C.
Published: December 2017

Oxygen consumption, body temperature (Tb), and evaporative water loss (mwe) were determined in intact Japanese quail (Coturnix coturnix), and in quail in which the hyoid musculature responsible for gular flutter had been surgically transected several days prior to study. Abolishing gular flutter reduced total mwe by an average of 20% at air temperatures (Ta) above 40 degrees C. Treated birds developed a significantly greater degree of hyperthermia during acute heat stress than the controls and, unlike the controls, were unable to maintain Tb less than Ta above 40 degrees C. These data demonstrate that gular flutter represents a significant cooling mechanism in heat-stressed quail.
Maturational changes of effective elastance in the first 10 days of life
Authors: Adler S. M. , Thach B. T. , Frantz I. D.
Published: December 2017

The effective elastance of the respiratory system (E‣rs) is a measure of its ability to resist a change in tidal volume under conditions of changing elastic loads. E‣rs was measured while subjects breathed air and 2% CO2 and 4% CO2 in air in two groups of premature infants of different gestational ages at 1 day 3–4 days, and 7–10 days of age. E‣rs was shown to decrease with increasing maturation and was independent of changes in control tidal volume. The decrease of E‣rs with increased gestational age could be accounted for by differences in calculated thoracic gas volumes in all but one instance, where E‣rs was lower in one group on the 3rd day of life. The activity of the Hering-Breuer reflex, as measured by the degree of slowing of inspiratory time after occlusion at FRC, has been previously reported to be normal to increased in similar infants. This suggests that differences related to size account for most of the maturational changes of E‣rs in newborns.
Autonomic origin of heart rate fluctuations at the onset of muscular exercise
Authors: Fagraeus L. , Linnarsson D.
Published: December 2017

The time courses of the heart rate (HR) changes were studied in six healthy male subjects who performed step changes from rest to light dynamic leg exercise (50 W) in the sitting position during a) control, b) parasympathetic blockade (atropine, 2–2.5 mg iv), c) beta-adrenergic blockade (propranolol, 10 mg iv), and d) during combined blockade with both drugs. During the control and beta-blockade experiments all subjects showed an immediate, rapid increase in HR, reaching a peak value after about 10 s, whereafter an equally rapid transient drop by 10–20 beats/min took place reaching the lowest values about 17 s after the onset of work. HR then again increased to reach a steady-state level within 60–90 s. In the atropine experiments this response pattern was not evident at all, whereas in the experiments with combined blockade it could be distinguished to a small, but significant degree. It is concluded that the observed fluctuations of HR at the onset of light dynamic exercise can be explained by a rapid vagal withdrawal, followed by a transient increase in vagal tone.
Maximum exercise heart rate reduction with maturation in the rat
Authors: Corre K. A. , Cho H. , Barnard R. J.
Published: December 2017

Maximum exercise heart rate decreases with maturation in the rat as well as in man. The present study was undertaken to investigate the mechanism(s) which might be responsible for this reduction in max exercise heart rate in the rat. Maximum exercise heart rates were 618 +/- 7 vs. 580 +/- 9 beats/min for the young (5 wk) and mature (19 wk) rats, respectively. Atropine had no effect on max exercise heart rate. Propranolol reduced max heart rate in both groups with the older rats having the lowest value. Resting heart rates were recorded following injections of atropine propranolol, and propranolol plus atropine. Under all conditions, including control, heart rates were lower in the mature rats. Electrical stimulation in situ showed a significant difference in the threshold voltage for stimulation at 600 beats/min: 1.1 +/- 0.2 vs. 1.6 +/- 0.1 V for the young and mature rats, respectively. These data suggest that intrinsic changes occur in the myocardium with maturation and the reduction in max exercise heart rate is due to these intrinsic changes as opposed to changes in neural influences.
Adrenergic receptors and vascular resistance in cerebral circulation of the cat
Authors: Muravchick S. , Bergofsky E. H.
Published: December 2017

Infusion of catecholamines and pharmacologic blockade were used to demonstrate the presence of an adrenergic receptor system with both alpha and beta components inthe feline cerebral vasculature. For this purpose, the anatomically isolated brain preparation was perfused under controlled constant-pressure conditions to eliminate active autoregulatory changes and passive fluctuations in calculated cerebral vascular resistance (CVR) secondary to alterations of perfusion pressure. Alpha adrenergic activity was demonstrated as substantial cerebral vasoconstriction in response to infusions of l-norepinephrine and epinephrine; cerebral blood flow (CBF) was decreased by mean values of 25% and 29%, respectively, with calculated increases in CVR of 82% and 62%, respectively. Marked reductions in the vasoconstriction produced by these two catecholamines followed the use of the alpha receptor blocking drug, phenoxybenzamine. Isoproterenol consistently produced cerebral vasodilation (mean CVR decrease of 22%), and this vasodilation was blocked during infusion of a specific beta adrenergic blocking agent, propranolol. Histamine vasodilation (mean CBF increase 49%) appeared to be independent of the classic adrenergic mechanisma. The observed responses are explained on the basis of a functionally significant cerebrovascular adrenergic system having high specificity and demonstrating considerable potency. The data also indicate a predominance of alpha over beta adrenergic cerebrovascular reception.
Determing the pulmonary excretion rate of carbon monoxide in newborn infants
Authors: Ostrander C. R. , Johnson J. D. , Bartoletti A. L.
Published: December 2017

A simplified technique was devised for measurement carbon monoxide excretion rates in newborn infants. Determinations can be performed quickly and repetitively in a noninvasive manner, with a sensitivity sufficient for use even on small preterm infants. Resolution of the method is +/- 4.3 mul/h (SD); however, variations in infant respiration rate may cause much greater changes in actual excretion rate. Preliminary results with five full-term newborn agree to within 15% of previously reported data. The system will be used extensively in ongoing studies involving total bilirubin production as a function of gestational age.
Design improvement for the Scholander gas analyzer
Authors: Farquhar D. N.
Published: December 2017

A simple design improvement is presented which eliminates stopper leakage and improves the reliability and convenience of the Scholander gas analyzer.
An intraluminal transducer/telemetry system for oviductal motility studies
Authors: Blair W. D. , Gilliland B. E. , Sauer B. W.
Published: December 2017

A method for measurement of changes in lumen diameter of the oviduct has been developed. Miniature intraluminal “doughnut-shaped” transducers, 1.0–1.2 mm in diameter, constructed from conductive silicone rubber are implanted in the rabbit isthmus and respond to localized changes--increases or decreases--in lumen diameter. Multiple transducer implants in the same tube permit rate as well as direction of contractions to be determined. A custom-designed, micropower dual-channel telemetry system was fabricated to record motility from unrestrained animals. Typical data collected using this system to determine the effects of induced ovulation on instantaneous changes in lumen diameter are presented.
A pressure- and flow-insensitive reference electrode liquid junction
Authors: Crandall E. D. , DeLong J.
Published: December 2017

The design and construction of a pressure- and flow-insensitive reference liquid junction for use in ion concentration electrode measuring systems is described. The junction is inexpensive, is very easily and rapidly constructed, is rugged, and is adaptable to various applications. When used in apH-measuring system, drift, pressure artifacts, and flow artifacts are negligible. The response time of the system appears to be less than 10 ms. Using the pH electrode device as described, the dissociation reaction rate constant of H2CO3 at 24 degrees C was determined to be 22 s-1.
Nocturnal lowering of thresholds for sweating and vasodilation
Authors: Wenger C. B. , Roberts M. F. , Stolwijk J. A. , Nadel E. R.
Published: December 2017

Six subjects exercised on a bicycle ergometer at 60–70% of maximal aerobic power in a 25 degrees C ambient. Experiments on each subject wereconducted at night (4:00–5:30 A.M.) and in daytime (noon-4:30 P.M.).Chest sweating rate (msw) was measured with resistance hygrometry. Forearm blood flow (BF), with an arm skin temperature of 35.5 +/- 1.2 degrees C (SD), was measured with electrocapacitance plethysmography. Esophageal temperature (Tes) was measured with a thermocouple at the level of the left atriumand mean skin temperature (Tsk) was calculated from a weighted average of temperatures at three sites. Tes was corrected to a skin temperature of 33 degrees C as follows: T'es = Tes + (Tsk - 33 degrees C)/8. This correction reflects the relative contributions of Tes and Tsk to control of msw:T'es and BF:T'es relations were not consistently changed. In any given subject, thresholds for sweating and vasodilation were shifted about equally. These shifts averaged 0.57 degrees C (range: 0.23–0.93 degrees C)for msw and 0.63 degrees C (range: 0.17–0.98 degrees C)for BF.
Comparison of drug-induced responses of rabbit trachea and bronchus
Authors: Fleisch J. H. , Calkins P. J.
Published: December 2017

The effect of various smooth muscle stimulants and relaxants was examined on isolated rabbit trachea and bronchus. Trachea contracted maximally in response to carbachol, slightly to KCl, and there was no response to serotonin or PGF2alpha. Relaxation of carbachol-contracted trachea was elicited by papaverine, aminophylline, isoproterenol, bradykinin, or PGE2. Histamine also relaxed the rabbit trachea. However, bronchi from the same animal contracted to this amine. As was the case with trachea, the bronchi contracted maximally to carbachol and slightly to KCl; serotonin and PGF2alpha were inactive. Unlike trachea, only papaverine or aminophylline completely relaxedthe rabbit bronchus. The other relaxants tested produced smaller responses.Contractions induced by carbachol were blocked by atropine. Bronchial contractions caused by histamine were antagonized by pyrilamine. In contrast, relaxation of trachea caused by histamine was neither affected by pyrilamine nor burimamide, metiamide, or propranolol. We conclude that a lack of pharmacological uniformity exists in at least two smooth muscle subdivisions of a mammalian airway and that this must be taken into consideration when determining the action of drugs on the respiratory system.
Effects of body weight and food intake on pleasantness ratings for a sweet stimulus
Authors: Thompson D. A. , Moskowitz H. R. , Campbell R. G.
Published: December 2017

A physiological role for pleasure has been suggested from observations that glucose loads reduced pleasantness ratings for sweet stimuli in normal weight but not in weight-reduced subjects. This hypothesis was reexamined in fasting and food-loaded, lean and obese subjects. Magnitude estimates of sweetness and pleasantness were obtained for seven sucrose concentrations. Indices of obesity including percent overweight, percent body fat, and body mass index were calculated. Pleasantness ratings of fasting subjects either increased up to a moderate concentration and then declined (type I hedonic response) or increased monotonically with concentration (type II hedonic response). Both types of response were found in lean and obese subjects. Within each weight group there appeared a negative correlation between pleasantness response and indices of obesity. Caloric loads reduced hedonic ratings of type II lean and obese subjects, but did not affect pleasantness response of type I lean and obese subjects. These findings indicate the presence of an hedonic monitor biased by body weight and caloric intake. The data suggest a physiological role for pleasure in regulating body weight at different set points in lean and obese subjects.
Effects of limping on normal exercise response
Authors: Hughes R. L. , Frownfelter D. , Piergies M.
Published: December 2017

Ten subjects performed two identical exercise tests on a motor-driven treadmill while walking normally or while limping. The two tests were separated by a rest period sufficient to permit return to a base-line state and the sugjects were randomly assigned to a normal-limp or limp-normal exercise sequence. Work rate was varied progressively by increasing treadmill grade in 5-degree increments to a maximum of 20 degrees, while limping was induced by insertion of a 0.5-cm wooden spike under the heel of the dominant foot. At all work rates, limping produced consistent increases in all variablesstudied, except for tidal volume where a decrease was seen. At the highestwork rate these differences tended to disappear. Even considering the greater O2 consumption induced by limping, there were still significant (P lessthan 0.01) increases in both respiratory rate and ventilation at all but the highest work rate, accompanied by an insignificant fall in tidal volume.This suggests that these changes were not induced by the alterations in theinternal or external work of walking and that limping somehow alters the regulation of exercise hyperpnea.
Effect of volume history on successive partial expiratory flow-volume maneuvers
Authors: Wellman J. J. , Brown R. , Ingram R. H. , Mead J. , McFadden E. R.
Published: December 2017

In normal subjects, the second of two successive partial expiratory flow-volume (PEFV 2) curves often had higher isovolume maximal expiratory flow rates (Vmax) than the first (PEFV 1) (mean increase 30.2 +/- 13%). The higher Vmax on PEFV 2 was present only when there was a greater lung elastic recoil pressure (Pst(L)). In eight subjects the Pst(L) derived from sequential partial quasi-static pressure-volume curves, from interruption of the flow-volume maneuvers and at the start of the PEFV curves showed that isovolume upstream resistance increased although Vmax also increased after going to residual volume (RV). In four subjects the RV volume history did not change the pressure flow relationship across the upstream airways. If airways dimensions were the sole determinant of Vmax, then Vmax on PEFV 2 would be the same or smaller than on PEFV 1. That the opposite was observed in our study indicates that the increase in Pst(L), which results from parenchymal hysteresis, offsets any dimensional decrease in upstream airways due to airways hysteresis.
PO2 in the carotid body perfused and/or superfused with cell-free media
Authors: Whalen W. J. , Nair P.
Published: December 2017

We measured with a micro-O2 electrode the tissue PO2 (PtO2) in the cat carotid body (CB) to see whether it was adequately oxygenated when perfused or superfused with artificial, cell-free (c-f) solutions (pH = 7.4; temp = 35–38 degrees C). To obtain a relative measure of O2 consumption (VO2), we also measured the rate of disappearance of O2 following stoppage of the blood flow, and compared these disappearance curves with those during stoppage of the c-f perfusion solutions. In 14 cats normal (blood perfusion) PtO2 values ranged from 10 to 104 mmHG; chi = 72 +/- 4 (SE--as used throughout). During 3 h of c-f perfusion with air-equilibrated Locke's solution, PtO2 ranged from 62 to about 160 mmHg; chi = 133 +/- 4. When perfused with Fay's equilibrated with 98% O2–2% CO2 no PtO2 values in the CB were below 300 mmHg (4 cats). In eight additional cats the CB was cleared of blood then superfused with saline equilibrated with 50% O2 underneath and air-equilibrated saline over. Less than 5% of the PtO2 values found were below 5 mmHg. We conclude that most studies on the artificially perfused or superfused CB cannot be invalidated on the basis that the preparations were hypoxic. O2 disappearance curves taken during blood perfusion were significantly faster than during c-f perfusion indicating a marked reduction in VO2 with c-f perfusion.
Effect of increased gas density on pulmonary gas exchange in man
Authors: Wood L. D. , Bryan A. C. , Bau S. K. , Weng T. R. , Levison H.
Published: December 2017

Pulmonary gas exchange was measured in seven resting supine subjects breathing air or a dense gas mixture containing 21% O2 in sulfur hexafluoride (SF6). The mean value of the alveolar-arterial oxygen difference (AaDO2) decreased from 12.4 on air to 7.0 on SF6 (P less than 0.01), and increased again to 13.4 when air breathing resumed (P less than 0.01). No differences occurred between gas mixtures for O2 consumption, respiratory quotient, minute ventilation, breathing frequency, heart rate, or blood pressure, and theimproved oxygen transfer could not be attributed to changes in cardiac output or mixed venous oxygen content in the one subject in which they were measured. These results are best explained by an altered distribution of ventilation during dense gas breathing, so that the ventilation-perfusion ratio(VA/Q) variance was reduced. Of several considered mechanisms, we favor onein which SF6 promotes cardiogenic gas mixing between peripheral parallel units having different alveolar gas concentrations. This mechanism allows forobserved increases in arterial carbon dioxide tension and dead space-to-tidal volume ratio during dense gas breathing, and suggests that intraregionalVA/Q variance accounts for at least one-half of the resting AaDO2 in healthysupine young men.