bluuebunny/crossref_metadata_2025 huggingface dataset:
Gustatory perception of sour, sweet, and salt mixtures using parotid gland flow rate
Authors: Feller Ralph P. , Sharon Irving M. , Chauncey Howard H. , Shannon Ira L.
Published: December 2017

The reflex secretion of parotid saliva was utilized to evaluate the stimulatory action of various taste mixtures on human gustatory chemoreceptors. Test solutions consisted of citric acid, sucrose, and sodium citrate. Rates of secretion were determined by measuring the volume produced by a standardized application procedure. The response elicited by the different solutions was determined. The effect of one modality upon another was then studied by combining two solutions at each of four concentrations. Results showed that the addition of citric acid or sodium citrate to sucrose produced a response equal to the sum of the separate constituents. The flow rate obtained from mixtures of citric acid and sodium citrate was less than the sum of the individual components. This apparently was due to the buffering effect causing a decreased hydrogen ion concentration. Although the hydrogen ion concentration decreased to sub-threshold levels, the salivary gland secretion rate was still responsive to variations in hydrogen ion concentration, indicating a synergistic effect when hydrogen and sodium ions were present in the same solution.

gustation; taste; gustatory-salivary reflex; parotid gland secretion

Submitted on October 1, 1964
Exercise, hypophysectomy, and spleen weight
Authors: Tipton C. M. , Tharp G. D. , Schild R. J.
Published: December 2017

Page 1163: Tipton, C. M., G. D. Tharp, and R. J. Schild, “Exercise, hypophysectomy, and spleen weight.” In Table 2 (p. 1165) under spleen weight for hypophysectomy, the values should read 284±18 for nontrained and 226±8 for trained.
Effect of continuous pressure breathing on right ventricular volumes
Authors: Wong Maylene , Escobar Edgardo E. , Martinez Gilberto , Butler John , Rapaport Elliot
Published: December 2017

We measured the end-diastolic volume (EDV) and stroke volume (SV) in the right ventricle of anesthetized dogs during continuous pressure breathing and compared them to measurements taken during breathing at atmospheric pressure. During intratracheal positive-pressure breathing, EDV, and SV decreased and end-diastolic pressure became more positive relative to atmospheric pressure. During intratracheal negative-pressure breathing, EDV enlarged and SV tended to increase; end-diastolic pressure became more negative. During extrathoracic negative-pressure breathing SV decreased, EDV fell, though not significantly, and end-diastolic pressure rose, but insignificantly. Changes in EDV observed during intratracheal positive-pressure breathing and intratracheal negative-pressure breathing were associated with minor shifts in transmural pressure (end-diastolic pressure minus intrapleural pressure) in the expected directions, but during extrathoracic negative-pressure breathing a large increase in transmural pressure took place with the nonsignificant reduction in EDV. We believe that intrathoracic pressure influences right ventricular filling by changing the peripheral-to-central venous pressure gradient. The cause of the alteration in diastolic ventricular distensibility demonstrated during extra-thoracic negative-pressure breathing remains unexplained.

positive-pressure breathing; negative-pressure breathing; extrathoracic negative-pressure breathing

Submitted on August 16, 1966
Measurement of oxygen consumption of rat bone marrow cells by a polarographic method
Authors: Gesinski R. M. , Morrison J. H. , Toepfer J. R.
Published: December 2017

Page 751: R. M. Gesinski, J. H. Morrison, and J. R. Toepfer. “Measurement of oxygen consumption of rat bone marrow cells by a polarographic method.” An incorrect value for the Bunsen coefficient was used in calculating oxygen consumption. All values given for microliters of oxygen consumed—in the text, figures, and all tables—should be corrected by dividing by a factor of 4.77. This correction does not alter the interpretations made in the paper but only the magnitude of the consumption reported.
Production of gas bubbles in fluids by tribonucleation
Authors: Ikels Kenneth G.
Published: December 2017

This report describes a mechanism, called tribonucleation, for producing gas nuclei by making and breaking contact between solid bodies which are immersed in liquid. A metal ball was rolled inside a glass tube filled with liquid which contains dissolved gas. Formed nuclei may grow to visible bubbles depending on the dissolved gas concentration and pressure applied to the liquid. Unlike other possible mechanisms for forming bubbles, tribonucleation is capable of producing nuclei under relatively mild experimental conditions, such as may be encountered in vivo. The experiments show that viscosity and velocity of separation of surfaces are important determinants of whether or not nuclei will form.

bubble formation; decompression sickness

Submitted on August 20, 1969
Enhanced carotid sinus baroreflex responses in dogs with chronic A-V block
Authors: DiSalvo J. , Reynolds R. , Robinson J. L. , Grupp G.
Published: December 2017

Effects of carotid sinus pressure on arterial pressure, atrial rate, and ventricular rate were examined in anesthetized normal dogs and in dogs with chronic complete A-V block. Change in arterial pressure per mmHg change in sinus pressure was 0.8 plus or minus 0.2 mmHg for controls but increased (P is less than 0.001) to 1.6 plus or minus 0.1 mmHg in A-V blocked dogs. Arterial pressure was 140–145 mmHg at low sinus pressure in both groups, but at high sinus pressure arterial pressure was significantly lower in A-V blocked dogs (44 plus or minus 4 mmHg) than in controls (92 plus or minus 8 mmHg). These differences were virtually abolished after vagotomy. Heart rate increased in normal dogs as sinus pressure was increased before vagotomy, but decreased after vagotomy. In blocked dogs atrial and ventricular rates decreased at high sinus pressure either before or after vagotomy. The results show that reflex circulatory responses to changes in carotid sinus pressure are enhanced in dogs with A-V block. This enhancement may involve attenuation of buffering influences exerted from other baroreceptors whose afferents are in the vagus nerves.
Role of peripheral and central chemoreceptors in the initiation of fetal respiration
Authors: Chernick V. , Faridy E. E. , Pagtakhan R. D.
Published: December 2017

The relationship between fetal femoral arterial P02 and PC02 was evalulated in 13 fetal sheep with intact and denervated peripheral chemoreceptors. With intact chemoreceptors, a significant relationship was found between fetal Pa02 and PaC02 at the time of the first breath (Pa02 = 2.57 + 0.09 PaC02; r = 0.62, P less than 0.05)mfollowing bilateral carotid sinus nerve section (CSN) or total peripheral chemodenervation (TD), PaC02. Comparison of the intact, CSN, and TD blood gases at the time of the first breath demonstrated that a) severe hypoxemia stimulates fetal respiration even following total peripheral chemodenervation; b) fetal central chemoreceptors do not respond to PaC02; c) PaC02 acting via peripheral chemoreceptors has a minor modulating effect on the degree of hypoxemia required to initiate fetal respiration. At a PaC02 below 40 mmHg this effect is inhibitory, acting via the carotid body. At a PaC02 above 90 mmHg this effect is stimulatory, acting via both carotid and aortic bodies.
Effect of intrathoracic pressure on pressure-volume characteristics of the lung in man
Authors: Goldberg H. S. , Mitzner W. , Adams K. , Menkes H. , Lichtenstein S. , Permutt S.
Published: December 2017

Quasi-static pressure-volume (P-V) curves in normal seated human subjects were determined with pressure at the airway opening (Pa0) set below (negative pressure), above (positive pressure), or equal to ambient pressure. Dynamic compliance (Cdyn) during controlled continuous negative pressure breathing (CNPB) was also studied. Quasi-static P-V curves at negative pressure were decreased in slope, reflected a decrease in total lung capacity, and intersected the P-V curve obtained at ambient Pa0. At positive pressure the P-V curves showed an increase in slope and an increase in total lung capacity. During CNPB a fall in Cdyn was found. The fall in Cdyn was rapid and persisted for the duration of CNPB. Cdyn promptly returned to control levels when Pa0 was adjusted to ambient pressure.
Pulmonary diffusing capacity and capillary blood volume in aging dogs
Authors: Robinson N. E. , Gillespie J. R.
Published: December 2017

Single-breath carbon monoxide diffusing capacity (DLco), pulmonary capillary blood volume (Vc), and membrane diffusing capacity (Dm) were measured in 24 beagle dogs aged 289–3,882 days. DLco and Vc were a function of age and alveolar volume (Va). Vc decreased with age resulting in changes in DLco. Changes in Vc may have been due to pulmonary morphological changes or to an exaggerated decrease in pulmonary blood flow in old dogs in response to 20–30 cmH-2O transpulmonary pressure. There was no age-related change in Dm.
Effects of lung inflation on pulmonary arterial blood volume in intact dogs
Authors: Wanner A. , Zarzecki S. , Sackner M. A.
Published: December 2017

The isolated effects of alterations of lung inflation and transmural pulmonary arterial pressure (pressure difference between intravascular and pleural pressure) on pulmonary arterial blood volume (Vpa) were investigated in anesthetized intact dogs. Using transvenous phrenic nerve stimulation, changes in transmural pulmonary arterial pressure (Ptm) at a fixed transpulmonary pressure (Ptp) were produced by the Mueller maneuver, and increases in Ptp at relatively constant Ptm by a quasi-Valsalva maneuver. Also, both Ptm and Ptp were allowed to change during open airway lung inflation. Vpa was determined during these three maneuvers by multiplying pulmonary blood flow by pulmonary arterial mean transit time obtained by an ether plethysmographic method. During open airway lung inflation, mean (plus or minus SD) Ptp increased by 7.2 (plus or minus 3.7) cmH2O and Ptm by 4.3 (plus or minus 3.4) cmH2O for a mean increase in Vpa by 26.2 (plus or minus 10.7) ml. A pulmonary arterial compliance term (Delta Vpa/Delta Ptm) calculated from the Mueller maneuver was 3.9 ml/cmH2O and an interdependence term (Delta Vpa/Delta Ptp) calculated from the quasi-Valsalva maneuver was 2.5 ml/cmH2O for a 19% increase in lung volume, and 1.2 ml/cmH2O for an increase in lung volume from 19% to 35%. These findings indicate that in normal anesthetized dogs near FRC for a given change in Ptp and Ptm the latter results in a greater increase of Vpa.
A circuit for measuring maximum negative or positive potentials
Authors: Tiedeman J. S. , Aronson R. S. , Strauss H. C.
Published: December 2017

A circiut was designed for measuring maximum negative or positive potentials occurring during an action potential. The basic functional unit is a peak-holding circuit that is reset following each action potential. The output of the circuit is displayed on a digital meter and may also be used to drive a point plotter for a graphic presentation of data.
Cardiorespiratory effects of rapid saline infusion in normal man
Authors: Muir A. L. , Flenley D. C. , Kirby B. J. , Sudlow M. F. , Guyatt A. R. , Brash H. M.
Published: December 2017

We have studied the cardiorespiratory effects of the rapid infusion (100 ml/min) of 2 liters of saline in four normal seated subjects. Cardiac output and pulmonary arterial pressure increased, while vital capacity (VC) and total lung capacity (TLC) decreased. There was an increase in closing volume (CV) without any detectable change in lung compliance or flow-volume characteristics. There was an increase in Pao2 during infusion period which can be related to better matching of ventilation to perfusion and to improved hemoglobin transport. In the recovery stage as cardiac output, pulmonary arterial pressure, TLC, and VC all returned toward control values CV remained high. In two subjects CV occurred within the normal tidal range of ventilation and in these two subjects Pao2 fell significantly below values obtained in the control period. The results suggest that rapid saline infusion in man can cause interstitial edema and lead to premature airway closure and hypoxemia.
Altered control of skin blood flow at high skin and core temperatures
Authors: Wyss C. R. , Brengelmann G. L. , Johnson J. M. , Rowell L. B. , Silverstein D.
Published: December 2017

Five subjects were studied during periods of controlled increases and decreases in skin temperature (Ts) over the Ts range of 34–40 degrees C. One protocol was designed to observe changes in forearm blood flow (FBF) and heart rate (HR) with changes in core temperature (Tc; right atrial blood temperature and esophageal temperature were measured) with Ts held constant at two levels. FBF and HR changed linearly with Tc in the Tc range of 37–38 degrees C with Ts constant at 38 degrees C. A second protocol imposed Ts changes at two levels of Ts and Tc; this protocol also included a prolonged cooling period. The influence of Ts on FBF and HR was reduced when Ts changes occurred at an elevated Ts and Tc, and FBF showed considerable hysteresis during cooling. We conclude that a linear model for the control of FBF or HR is inadequate as a tool for predicting the control of these variables.
Regulation of frequency and depth of breathing during expiratory threshold loading in cats
Authors: Grunstein M. M. , Wyszogrodski I. , Milic-Emili J.
Published: December 2017

In six spontaneously breathing anesthetized cats, intermittently subjected to inspiratory elastic loads, we have studied the relationships between tidal volume (VT) and the durations of inspiration (Ti) and breath duration (Ttot) obtained during spontaneous ventilation from resting lung volume (FRCc) and from elevated end-expiratory levels. The latter was elevated by submerging the expiratory breathing line into a column of water, representing the addition of an expiratory threshold load (ETL). The VT vs. Ti relationships obtained at different end-expiratory levels were similar, indicating that during ETL the vagal mechanism regulating Ti responds only to lung volume changes above the new end-expiratory level and is independent of the absolute end-expiratory lung volume. Single vagal fiber recordings suggest that this effect on Ti control may be explained on the basis of adaptation occurring at the level of the pulmonary stretch receptors. The control of Ttot, on the other hand, was found to depend both on the Ti of the preceding breath (phasic component) and on a separate vagal mechanism specifically affecting the duration of expiration (Te) in response to changes in the absolute end-expiratory lung volume. The latter mechanism is functionally inoperative at FRCc.
A simplified method for determining the P50 of blood
Authors: Kirk B. W. , Raber M. B. , Duke K. R.
Published: December 2017

A method to determine the P50 of whole blood is described using a modified American Optical reflectance oximeter, pump, and membrane tonometer, together with PO2, PCO2, and pH measurements in a standard blood gas machine. Determinations of P50 were made in 66 patients and normal subjects and in two situations where P50 was very low and very high. The results were compared to oxygen saturations calculated from measured oxygen content. The directly determined oxygen saturation agreed with the assumed saturation of 50 per cent in the oximeter within 0.5 per cent. The apparatus appears to be a simple and relatively inexpensive method to obtain P50 as long as blood carboxyhemoglobin or methemoglobin contents are not elevated.
Effect of head skin temperature on tympanic and oral temperature in man
Authors: McCaffrey T. V. , McCook R. D. , Wurster R. D.
Published: December 2017

Five subjects were sequentially heated and cooled in a double-climate chamber while mean skin temperature (except the head) and head skin temperature were separately varied. The tympanic membrane temperatures of these subjects were disproportionately influenced by changes in head skin temperature. By heating and cooling localized regions of the head, changes in tympanic membrane temperature that followed changes in skin temperature on the ipsilateral side of the head could be produced. During heating of the head, oral and tympanic membrane temperatures were influenced to a similar degree, while esophageal temperature remained essentially unaffected. However, under conditions in which the legs and feet were heated in a water bath, esophageal temperature showed more rapid changes than either tympanic membrane or oral temperature. These findings suggest that tympanic membrane temperature and, to a lesser degree, oral temperature may be affected by thermal exchange occurring between arteries and veins in the cervical and cephalic regions. In addition, the ability to influence selectively esophageal and tympanic membrane temperatures brings into question the arbitrary use of these measurements under widely different experimental conditions as estimates of core temperature.
Turnover of free fatty acids during recovery from exercise
Authors: Hagenfeldt L. , Wahren J.
Published: December 2017

The turnover of plasma free fatty acid (FFA) was studied during the recovery from exercise with the aid of a continuous infusion of 14C-labeled oleic acid. Arterial FFA reached a maximum of twice the exercise value after 6 min of recovery and was still 75% above the basal level after 20 min. Within 2 min after exercise, plasma radioactivity had increased and the specific activity of plasma oleic acid had fallen. The rate of uptake of FFA from the plasma pool rsoe by 40% during the first minutes after exercise. The rate of release of FFA to the plasma pool showed a peak 2 min after exercise and was thereafter about 40 mumol/min lower than the rate of uptake. The fractional turnover of FFA decreased to resting levels within 5–10 min after exercise. It is concluded that the postexercise peak in arterial FFA is a consequence of augmented release of FFA into the plasma pool above the level during exercise, possibly related to the release of sympathetic vasoconstrictor tone. As a consequence, the rate of removal of FFA rises at the end of exercise and remains augmented above the basal level for as long as the arterial concentration is increased.
Motion of both mitral valve leaflets: a cineroentgenographic study in intact dogs
Authors: Tsakiris A. G. , Gordon D. A. , Mathieu Y. , Irving L.
Published: December 2017

Motion and position of both mitral leaflets were studied in five normal dogs 1–11 wk after radiopaque markers were sutured on the valve cusps and on the mitral annulus. Cinefluorograms and cineangiograms (100–120 frames/s) of left atrium and left ventricle were used to study cusp motion and intraventricular flow patterns, and to detect mitral regurgitation during sinus rhythm (42–184 beats/min) and during isolated atrial or ventricular contractions. Time-motion of both leaflets was similar throughout diastole with the exception of delayed posterior cusp opening. Peak opening and closing speeds, opening and closing times, and time of complete closure, measured from the Q wave of the ECG, were not significantly affected by the variations in heart rate. Diastolic leaflet closure began immediately after opening, while the ventricular cavity was small, and was caused by flow eddies behind the cusps. Isolated ventricular contractions closed the valve leaflets completely and symmetric valve closure was ensured by the different rates of leaflet edge approximation. In contrast, atrial closure was slow, partial, and of very short duration.
Effect of baroreceptor activity on ventilatory response to chemoreceptor stimulation
Authors: Heistad D. , Abboud F. M. , Mark A. L. , Schmid P. G.
Published: December 2017

This study tested the hypothesis that ventilatory responses to chemoreceptor stimulation are affected by the level of arterial pressure and degree of baroreceptor activation. Carotid chemoreceptors were stimulated by injection of nicotine into the common carotid artery of anesthetized dogs. Arterial pressure was reduced by bleeding the animals and raised by transient occlusion of the abdominal aorta. The results indicate that ventilatory responses to chemoreceptor stimulation were augmented by hypotension and depressed by hypertension. In additional studies we excluded the possibility that the findings were produced by a direct effect of changes in arterial pressure on chemoreceptors. Both carotid bifurcations were perfused at constant flow. In one carotid bifurcation, perfusion pressure was raised to stimulate carotid sinus baroreceptors. In the other carotid bifurcation, pressure was constant and nicotine was injected to stimulate carotid chemoreceptors. Stimulation of baroreceptors on one side attenuated the ventilatory response to stimulation of contralateral chemoreceptors. This inhibition was observed before and after bilateral cervical vagotomy. We conclude that there is a major central interaction between baroreceptor and chemoreceptor reflexes so that changes in baroreceptor activity modulate ventilatory responses to chemoreceptor stimulation.
Some factors affecting tissue Po2 in the carotid body
Authors: Whalen W. J. , Nair P.
Published: December 2017

In the carotid body (CB) of the anesthetized cat tissue Po2 (Pto2) measured with a micro O2 electrode averaged about 65 mmHg at normal arterial pressure (mean = 96 mmHg). Pto2 correlated significantly with the hematocrit of the arterial blood but not with % saturation. When arterial pressure was reduced (mean = 58 mmHg) by bleeding Pto2 fell significantly. Phentolamine injection (1 mg/kg iv) at the reduced pressure caused Pto2 to rise significantly. At normal arterial pressure blowing moistened O2 over the CB did not affect Pto2 if the electrode tip was about 90 mum into the CB. At a reduced pressure (and blood flow) the sensitive depth increased to about 301 mum, and to about 600 mum when flow was stopped. We concluded that a) the increased chemoceptor discharge usually seen with hemorrhage is due to reduced Pto2; b) the reduction in Pto2 is probably due to reduced blood flow which is, in turn, caused partly, at least, by sympathetic nervous system activity; c) O2 content, rather than Po2, may determine chemoreceptor discharge rate; and d) there are no barriers in the CB which are impermeable to O2.
Surgical techniques for long-term studies of thoracic duct circulation in the rat
Authors: Girardet R. E.
Published: December 2017

Two techniques for cannulation of the thoracic duct in the rat, thoracic duct shunt and thoracic duct side fistula, are described. They give access, for repetitive sampling, to a normal thoracic duct circulation and are suited for study of the circulation under physiologic conditions. The thoracic duct shunt creates, with tubing, a shunt between the caudad and cephalad ends to the cisterna chyli. The exteriorized midportion of the shunt allows observation of the lymph. In the thoracic duct side fistula, the short arm of a T tube is placed within the cisterna and sampling is done via the long arm of the tube. Ten shunts functioned for 8–26 days and 10 side fistulas functioned for 8–30 days. Average lymph flow was 0.044 ml/min (shunts) and 0.042 ml/min (side fistulas). Average thoracic duct lymphocyte output was 1,729,000 cells/min (shunts) and 2,310,000 cells/min (side fistulas). Average blood lymphocyte count was 11,700 cells/mm3 (shunts) and 12,600 cells/mm3 (side fistulas). All parameters remained stable during the period of study. Advantages of those techniques over the Bollman end fistula are presented.
Effects of expiratory threshold loading during steady-state exercise
Authors: Goldstein I. , Goldstein S. , Urbanetti J. A. , Anthonisen N. R.
Published: December 2017

Increases in functional residual capacity (FRC) decrease inspiratory muscle efficiency; the present experiments were designed to determine the effect of FRC change on the ventilatory response to exercise. Six well-trained adults were exposed to expiratory threshold loads (ETL) ranging from 5 to 40 cmH2O during steady-state exercise on a bicycle ergometer at 40–95% VO2max. Inspiratory capacity (IC) was measured and changes of IC interpreted as changes of FRC. ETL did not consistently limit exercise performance. At heavy work (greater than 92% VO2max) minute ventilation decreased with increasing ETL; at moderate work (less than 58% VO2max) it did not. Decreases in ventilation were due to decreases in respiratory frequency with prolongation of the duration of expiration being the most consistent change in breathing pattern. At moderate work levels, FRC increased with ETL; at maximum work it did not. Changes in FRC were dictated by constancy of tidal volume and a fixed maximum end-inspiratory volume of 80–90% of the inspiratory capacity. When tidal volume was such that end-inspiratory volume was less than this value, FRC increased with ETL. Mouth pressure measured during the first 0–1 s of inspiratory effort against an occluded airway (P0-1) was increased by ETL equals 30 cmH2O, in spite of the fact that ventilation was decreased. We concluded that changes in FRC due to ETL had no effect on the ventilatory response to exercise and that changes in P0-1 induced by ETL did not reflect changes of inspiratory drive so much as changes of the pattern of inspiration.
A design improvement in continuous blood sampling and analysis for glucose in rest and exercise
Authors: Tzankoff S. P. , Leatherman N. E. , Robinson S.
Published: December 2017

In the past 15 yr attempts to sample blood continuously for glucose analysis with the AutoAnalyzer (Technicon Corp.) have been reasonably successful in resting subjects. However, they have sometimes required heparinization of the subjects so as to avoid clotting in the tubes of the system. To avoid the hazards of heparinization during exercise, a method is described for sampling and analyzing blood glucose continuously with the AutoAnalyzer, using a specially designed male Luer adaptor which fits into disposable Teflon catheters.
Fever: exchange of shivering by nonshivering pyrogenesis in cold-acclimated guinea pigs
Authors: Blatteis C. M.
Published: December 2017

The pyrogenic response of adult, unanesthetized guinea pigs to 2 mug/kg iv of Salmonella enteritidis endotoxin was measured at 27 and 7 degrees C ambient temperatures, both before and after an 8-wk exposure to 7 degrees C. There were no significant differences between the onset, maximum height, and total duration of the fevers produced before and after cold acclimation in both thermal environments. However, in 27 degrees C, before cold acclimation, fever production was associated with vigorous shivering activity; two temperature maxima typically developed. After cold acclimation, visible shivering was not detectable during pyrogenesis; moreover, only a single maximum occurred, culminating during the interval between the two rises previously. In 7 degrees C, shivering occurred in both the non-cold- and cold-acclimated endotoxin-treated guinea pigs, but the increase in oxygen consumption was significantly greater in the latter. These results indicated, therefore, that nonshivering (NST) replaces shivering thermogenesis (ST) in a thermoneutral, while ST is added onto NST in a cold, environment in cold-acclimated guinea pigs in supplying the necessary heat for fever production, and that these effects involve alterations in the character of the febrile course.
Effects of cholinergic stimulation on human esophageal peristalsis
Authors: Hollis J. B. , Castell D. O.
Published: December 2017

The effects of cholinergic stimulation on esophageal peristalsis were studied in normal subjects. An intraesophageal transducer assembly was used to measure the dynamics of esophageal peristalsis before and after edrophonium chloride, 80 mug/kg intravenously. Following endrophonium, there was a marked increase in amplitude of esophageal persistalsis associated with a significant reduction in velocity of esophageal peristalsis and a significant increase in width and time of appearance of the contraction wave following a swallow. Graded doses of endrophonium all resulted in significant increases in peristaltic amplitude with the maximal response occurring at doses of 80 and 160 mug/kg. Similar results were obtained with a more direct-acting cholinergic agent, bethanechol, 80 mug/kg subcutaneously. The relevance of these results as an indication of the importance of cholinergic innervation in regulating esophageal motility are discussed.
Comparative evaluation of pressure and time factors in estimating left ventricular performance
Authors: Abel F. L.
Published: December 2017

Left ventricular and ascending aortic pressures were measured in open chest mongrel dogs under pentobarbital anesthesia. The data were digitized, averaged, and subgrouped by mean systolic aortic pressures (MSAP), end-diastolic pressure (EDP), and heart rate (HR). Seven raw and 32 derived variable from the pressure, as a function of time, wave forms were analyzed in each subgroup in the control state and following the infusion of catecholamines. A plot of control variability versus sensitivity to norepinephrine indicates that time to peak ventricular pressure (PVP time) is a more sensitive indicator of changes in the inotropic state than such other commonly used variables as max dP/dt, integrated isometric tension, and (max dP/dt)/developed pressure. PVP time also showed less variability with HR, EDP, and MSAP. Regression lines were also fit to the data using a second-order model. This permitted evaluation of experimentally varying either HR, EDP, or MSAP while maintaining the other two constant. PVP time was again one of the better variables in terms of sensitivity to HR, EDP, or MSAP. Vmax, fractional rate of change of power, preejection period, and systolic time were also analyzed and compared with PVP time using averaged data.
Effect of ether on control of rate and depth of breathing in newborn rabbits
Authors: Thach B. T. , Wyszogrodski I. , Milic-Emili J.
Published: December 2017

The effect of ether anesthesia on Hering-Breuer inflation reflexes of newborn rabbit pups was investigated. Studies were done at a level of anesthesia at which an apneustic pattern of respiration is seen in vagotomized animals. The hypothesis that increase in vagal influence on respiratory frequency is accompanied by increase in influence on contractile force of the inspiratory muscles was tested. Two aspects of the Hering-Breuer reflex, breath duration and airway pressure developed with an elastic load, were evaluated simultaneously. This was done by performing airway occlusions at FRC--the results expressed as percent slowing on occlusion and as effective elastance (E'rs). The animals were studied with and without anesthesia, before and after vagotomy. Anesthesia resulted in a marked increase in vagal influence on inspiratory duration (34% increase) and on total breath duration (36% increase). In contrast E'rs was decreased (20%) after anesthesia whereas passive elastance was slightly increased. The vagal contribution to E'rs was essentially the same before and after anesthesia (36–38%). Thus ether anesthesia increases one aspect of the Hering-Breuer reflex without changing the other. These findings are likely due to depression of the central nervous system rather than due to peripheral effects of ether.
Light-absorbing properties, stability, and spectral stabilization of indocyanine green
Authors: Landsman M. L. , Kwant G. , Mook G. A. , Zijlstra W. G.
Published: December 2017

The absorption spectrum of indocyanine green depends on the nature of the solvent medium and on the dye concentration. Binding to plasma proteins causes the principal peaks in the absorption spectrum to shift about 25 nm toward the higher wavelengths. The much greater influence on the spectrum of the dye concentration results from progressive aggregate formation with increasing concentration. Indocyanine green solutions therefore do not follow Lambert-Beer's law above 15 mg-I-1 (in plasma). Indocyanine green solutions in plasma and concentrated (1,000 mg-I-1) solutions in distilled water are stable for at least 4 h. In long-term experiments the optical density of indocyanine green solutions in plasma as well as in distilled water generally diminishes, even in the dark. On the 7th day a new absorption maximum starts to appear at gamma=900 nm, possibly caused by further aggregate formation leading to much larger particles. Spectral stabilization after injection of a concentrated solution into the blood is most rapid when the dye is dissolved in distilled water. Spectral stabilization slows down with decreasing temperature. As rapid spectral stabilization is essential in quantitative dye dilution studies, the practice of adding a albumin and/or isotonic saline solution to the injectate should be discontinued. When a 10 g-1(-1) aqueous solution of indocyanine green is used, spectral stabilization takes less than 1.5 a (at 37 degrees C), which is sufficiently fast for almost any application.
Oxygen consumption in relation to work load in students with cerebral palsy
Authors: Lundberg A.
Published: December 2017

Eighteen adolescents with various forms of cerebral palsy performed tests on a mechanically braked ergometer bicycle. VO2 was measured at different loads and net mechanical efficiency calculated. It was found that efficiency was poor at light loads for most of the students but that there were significant intergroup differences in mechanical efficiency at higher loads. The leveling-off plateau demonstrated by healthy adolescents was only attained by a few of the disabled students. It was concluded that the muscle hypertonia and involuntary movements were responsible for the high level of energy expended in the mechanical work performed.
Plasma vasopressin and renin activity in women exposed to bed rest and +Gz acceleration
Authors: Keil L. C. , Ellis S.
Published: December 2017

To study the effect of prolonged recumbency on plasma vasopressin and renin activity, eight women (23–34 yr) were subjected to 17 days of absolute bed rest. The +3 Gz tolerance of the subjects was tested before and after 14 days of bed rest. From day 2 and through day 17 of bed rest, plasma arginine vasopressin (AVP) levels were reduced 33%. Plasma renin activity (PRA) increased 91% (P less than 0.05) above ambulatory control values from days 10 through 15 of bed rest. When compared to precentrifuge values, exposure to +3 Gz prior to bed rest provoked a 20-fold rise (P less than 0.05) in mean plasma AVP but resulted in only a slight increase in PRA. After bed rest, acceleration increased plasma AVP 7-fold (P less than 0.02); however, the magnitude of this increase was less than the post +3Gz value obtained prior to bed rest. After bed rest, no significant rise was noted in PRA following +3 Gz. This study demonstrates that prolonged bed rest leads to a significant rise in the PRA of female subjects, while exposure to +Gz acceleration provokes a marked rise in plasma AVP.
Lactate dehydrogenase changes following several cardiac hypertrophic stresses
Authors: York J. W. , Penney D. G. , Weeks T. A. , Stagno P. A.
Published: December 2017

The effects of four different cardiac hypertrophic stresses on cardiac lactate dehydrogenase (LDH) isozyme composition and activity were examined. Altitude-induced right ventricular hypertrophy was accompanied by an increase of 10% in the M subunit of LDH in right ventricle, left ventricle, and atria. Left ventricular hypertrophy induced by aortic stenosis also produced isozyme changes in the ventricles, but of only half the magnitude. Biventricular hypertrophy, induced by running or swimming, was accompanied by 4–5% increases in M LDH in the ventricles only. We conclude that changes in LDH activity are directly related to changes in the M subunit in all three portions of the heart. No changes in H subunit were noted under any of the stresses. It appears that the magnitude of changes in cardiac LDH isozyme composition are only marginally related to extent of hypertrophy.
Changes in the fluid compartments and dry weights of reimplanted dog lungs
Authors: Cowan G. M. , Staub N. C. , Edmunds L. H.
Published: December 2017

We studied changes in fluid compartments and dry weights of reimplanted lungs of dogs during the first 6 wk after operation. Excision and reimplantation caused a large increase in lung weight. The increase in weight was maximal 3 days after operation, was proportionately greater in the upper middle lobe than in the lower lobe, and was principally due to increased extravascular water. Dry weight and noncirculating red cells (measured by subtracting 51Cr-labeled red cell mass from total red cell mass as measured by hemoglobin extraction) also increased within 3 days after operation. Lung weight and extravascular water decreased progressively after 3 days and were normal in 6 wk. Chromated blood mass remaining within excised, passively drained lobes did not change at any stage postoperatively. Three days after operation, frozen lung sections showed minimal alveolar fluid but large amounts of peribronchial and perivascular edema which was occasionally blood tinged; submucosal edema was present in a few bronchi. Using intraalveolar Evans blue dye, we confirmed that several bronchial lymphatics close within 6 h and refenerate during the first postoperative week. Many of observed functional changes in freshly reimplanted lungs are temporally related to changes in extravascular water.
A new method to determine frequency characteristics of the respiratory system
Authors: Landser F. J. , Nagles J. , Demedts M. , Billiet L. , van de Woestijne K. P.
Published: December 2017

A technique is described allowing one to determine simultaneously the resistance and reactance of the total respiratory system for various frequencies. During spontaneous breathing, regularly recurring impulses are produced at the mouth by means of a loud speaker. A Fourier analysis of the mouth pressure and flow signals yields mean resistance and reactance values, over16 s, for all harmonics of 2 Hz up to 30 Hz. The values are in good agreement with those obtained in the absence of breathing and those determined by means of the forced oscillation technique and by body plethysmography. The reproducibility of the measurements is satisfactory (coefficient of variation: 11.6%).
Thermoregulatory response of women to intermittent work in the heat
Authors: Drinkwater B. L. , Denton J. E. , Raven P. B. , Horvath S. M.
Published: December 2017

Seven women worked intermittently in three randomly ordered sessions at 75% Vo2max at three temperatures, 28 degrees C (45% rh) 35 degrees C (65% rh), and 48 degrees C (10% rh) and recovered in a cool environment (22 degrees C) after each 6-min work period. Although Tre was higher in each successive work period, the ambient temperature had no effect on the cardiovascular or respiratory responses or on deltaTre. In all conditions SV decreased with time with a concomitant increase in HR to maintain Q. A fall in mean blood pressure from the initial to final measurement was due entirely to a decrease in diastolic pressure. The final Tre for these women was approximately equal to that previously reported for men working continuously for 1 h under conditions equivalent to time-weighted average of the thermal and metabolic loads during work and recovery in this study.
Effect of angiotensin on hypoxic pulmonary vasoconstriction in isolated dog lung
Authors: Alexander J. M. , Nyby M. D. , Jasberg K. A.
Published: December 2017

The effects of infused angiotensin on hypoxic pulmonary vasoconstriction in blood-perfused isolated dog lungs were studied. By using a double-perfusion system we were able to perfuse the right and left lungs separately in the same animal; one lung was used as control and the other lung was experimentally modified. The vasoconstrictive response to hypoxia decreased with time in the isolated lung preparations. The infusion of either angiotensin I or angiotensin II (1.2–5.8 mug/min) caused a threefold increase in the vasoconstrictive response to hypoxia over control levels. A second hypoxic period during the infusion usually yielded a diminished response, suggesting further degeneration of the response irreversible with angiotensin. It was concluded that angiotensin I or angiotensin II temporarily enhances hypoxicpulmonary vasoconstriction in isolated dog lungs.
Alkaline shift in lumbar and intracranial CSF in man after 5 days at high altitude
Authors: Weiskopf R. B. , Gabel R. A. , Fencl V.
Published: December 2017

In six healthy male volunteers at sea level (PB 747–759 Torr), we measured pH and PCO2 in cerebrospinal fluid (CSF), and in arterial and jugular bulb blood; from these data we estimated PCO2 (12) and pH for the intracranial portion of CSF. The measurements were repeated after 5 days in a hypobaric chamber (PB 447 Torr). Both lumbar and intracranial CSF were significantly more alkaline at simulated altitude than at sea level. Decrease in[HCO3-] IN lumbar CSF at altitude was similar to that in blood plasma. Bothat sea level and at high altitude, PCO2 measured in the lumbar CSF was higher than that estimated for the intracranial CSF. At altitude, hyperoxia, incomparison with breathing room air, resulted in an increase in intracranialPCO2, and a decrease in the estimated pH in intracranial CSF. With hyperoxia at altitude, alveolar ventilation was significantly higher than during sea-level hyperoxia or normoxia, confirming that a degree of acclimatization hadoccurred. Changes in cerebral arteriovenous differences in CO2, measuredinthree subjects, suggest that cerebral blood flow may have been elevated after 5 days at altitude.
Decompression-induced decrease in nitrogen elimination rate in awake dogs
Authors: D'Aoust B. G. , Smith K. H. , Swanson H. T.
Published: December 2017

Formulation of safe decompression procedures still requires unproven assumptions regarding both gas equilibration rates and the associated ascent criteria. Although the assumption of symmetry of uptake and elimination rates has been suspect for several years, few data are available. Measurements of actual mixed venous blood nitrogen content [vN2] during compression and following decompression in chronically catheterized awake dogs have clearly demonstrated that desaturation is markedly slower than saturation, and that this effect can be imposed by decompression. The disappearance of arteriovenous nitrogen concentration differences during desaturation following a decompression that produced decompression sickness indicates that cardiopulmonary and cardiovascular changes induced by mechanisms associated with decompression per se can potentiate its deleterious effects. Current US practices do not provide for such asymmetry, while those used in the UK have incorporated this in their models for the last decade.
Distribution of pulmonary resistance: effects of gas density, viscosity, and flow rate
Authors: Drazen J. M. , Loring S. H. , Ingram R. H.
Published: December 2017

Theoretical predictions of the distribution of inspiratory viscous pressure loss were made for canine and human pulmonary airways for gases with varying density and viscosity at different pulmonary flow rates. We predicted that in canine or human airways when tracheal flow was turbulent, most of the total calculated pressure loss would be in the first few branchings of the bronchial tree; however when tracheal flow was nearly laminar inspiratory pressure loss would be spread more uniformly along the airways. To test these predictions an airway catheter was used to partition total pulmonary resistance (RL) in five anesthetized dogs. On air the catheter was positioned such that the mean resistance mouthward of the catheter tip (Rc) at a flow of 0.5 1/s was 63% of RL. At the same catheter position Rc was 87% of RL when the dogs were breathing a mixture of 80% sulfur hexafluoride-20% oxygen and resistance was determined at 1.0 1/s. Rc was 50% of RL when the dogs were breathing a mixture of 80% helium-20% oxygen and resistance was determined at 0.25 1/s. Thus altering gas physical properties and flow rates changed the distribution of pulmonary resistance as predicted.
Terminal nitrogen rise
Authors: Martin C. J. , Das S. , Young A. C.
Published: December 2017

Eighteen-breath nitrogen washouts were performed on eight subjects. Each washout could be simulated by a four-compartment model, each compartment with a different ventilation-to-volume ratio and a variable contribution to expiratory flow. In large breaths initiated near residual volume, a terminal nitrogen rise (TNR) was seen. To account for the TNR with this model, there were relatively small changes in flow from compartments with markedly different nitrogen concentration. Reasons are given for believing these compartments could not be the upper and lower lung. Three of these subjects werestudied in the supine, seated, and head-down positions. The TNR was seen atthe same lung volume in all positions. At routine bronchospirometry in a second group of subjects, sampling with small catheters during a nitrogen washout showed a TNR in the expirate of lungs, lobes, segments, and subsegments in the upright and supine positions. Apparently a large vertical hydrostatic gradient is unnecessary to produce a TNR. Finally, the TNR was shown tooccur at that lung volume where transpulmonary pressure is very small and changing rapidly with volume. This TNR was often followed by a terminal nitrogen fall while the lung was continuing to empty. The TNR occurs when flow from a large poorly ventilated compartment increases relative to the flow from other compartments. A model of lung in which the poorly ventilated compartment develops high specific compliance at low lung volume explains thesedata.
Respiratory response to airway occlusion in infants: sleep state and maturation
Authors: Frantz I. D. , Adler S. M. , Abroms I. F. , Thach B. T.
Published: December 2017

The progressive respiratory response to occlusion of the airway at FRC was measured in a group of full-term and premature human infants. The sleep state of the full-term infants was shown to affect the response primarily through variations in the phase of thoracic and abdominal movements. The weakest responses were seen in those infants who demonstrated parodoxical respiration prior to occlusion. Most infants developed paradoxical respiratory movements after occlusion, but this did not affect the strength of the load-compensatory response. An increase in response related to both gestationaland postnatal age was observed. This increase could not be accounted for byvariations in the amount of paradoxical and in-phase respiration and thus may represent an increase in the sensitivity of infants to chemical stimuli with maturation.
Rapid, shallow breathing after Ascaris suum antigen inhalation: role of vagus nerves
Authors: Cotton D. J. , Bleecker E. R. , Fischer S. P. , Graf P. D. , Gold W. M. , Nadel J. A.
Published: December 2017

In five treadmill-exercising, unsedated dogs, we studied the effect of inhaled Ascaris suum antigen aerosols on minute volume of ventilation (VE), respiratory frequency (f), tidal volume (VT), total pulmonary resistance (RL), and dynamic pulmonary compliance (CLdyn), before and during cooling of the vagus nerves. With the vagi warm, inhaled antigen increased VE (mean + 62%; P less than 0.01)by increasing f (mean + 180%; P less than 0.01), despite a decrease in VT (mean - 42%; P less than 0.01). RL increased (mean + 170%; P less than 0.001) and CLdyn decreased (mean - 43%; P less than 0.005). With the vagi cool, inhaled antigen no longer affected VE, f, or VT (P greater than 0.5), although RL still increased and CLdyn still decreased. Inhalation of a bronchodilator, terbutaline, prevented the broncho-constriction induced by antigen but did not prevent the ventilatory response. We conclude that vagal afferent pathways mediate the ventilatory response to inhaled antigen and suggest that the primary stimulus for this response is not airway narrowing.