bluuebunny/crossref_metadata_2025 huggingface dataset:
Regional protein absorption rates from the pleural cavity in dogs
Authors: Negrini D. , Pistolesi M. , Miniati M. , Bellina R. , Giuntini C. , Miserocchi G.
Published: December 2017

In five supine spontaneously breathing anesthetized dogs we injected into the pleural space 0.5–1 ml of saline solution containing 2 mg/ml albumin labeled with technetium-99m. By use of a gamma camera placed horizontally over the chest, we followed, up to 120 min, the activity over the whole lung and over the preferential accumulation areas of the label (regions of interest, ROI) that corresponded to the apical, mediastinal, and laterodiaphragmatic regions. Activities were corrected for the decay rate of the isotope used. On the average, the activity over the whole lung decreased by 27% up to 120 min. The overall activity over the ROI amounted to 44.3% after the injection and decreased to 24% of total at 120 min, thus accounting for 75% of the total decrease in activity. At 10 min, the activity per unit surface of the gamma camera image (As) was from 2.2- to 5.7-fold higher over the ROI than for the rest of the lung image. The decrease of As at 120 min was 18-, 13-, and 5-fold greater for mediastinal, diaphragmatic, and apical regions, respectively, compared with the rest of the lung image. The time course of the changes in As are discussed in terms of regional albumin egress rate based on the functional interaction between the Starling and the lymphatic mechanisms.
Gas exchange and lactate anaerobic thresholds: inter- and intraevaluator agreement
Authors: Gladden L. B. , Yates J. W. , Stremel R. W. , Stamford B. A.
Published: December 2017

Twenty-four coded graph sets of gas exchange variables and blood lactate concentration (LA) plotted against time at 15-s intervals were analyzed by nine evaluators who determined the gas exchange (ATGE) and LA (ATLA) anaerobic thresholds. In addition, ATGE and ATLA were determined by a linear regression computer program. Agreement between ATGE and ATLA was poor; the median intraclass correlation coefficient (ri) was 0.53. Among evaluators, ATLA agreement (median ri = 0.81) was better than ATGE agreement (median ri = 0.70). In general, the ability of any evaluator to choose similar values from duplicate plots for either ATGE (median ri = 0.97) or ATLA (median ri = 0.995) was good. There was better agreement between the mean ATLA of the evaluators and the computer ATLA (ComLA) (ri = 0.88) than between the mean ATGE of the evaluators and the computer ATGE (ComVE), (ri = 0.58). Agreement between ComVE and ComLA was poor (ri = 0.29). These results suggest that ATGE does not accurately predict ATLA and that different evaluators choose different thresholds from the same data. Further assessment of the validity and precision of ATGE based on breath-by-breath and minute-by-minute data is needed.
Identification of canine pulmonary surfactant-associated glycoprotein A precursors
Authors: Weaver T. E. , Whitsett J. A. , Hull W. M. , Ross G.
Published: December 2017

Surfactant-associated glycoproteins A were identified by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of crude surfactant from canine alveolar lavage: an unglycosylated form (protein A1), 27,000–28,000 daltons; glycoprotein A2, 32,000–34,000 daltons; and glycoprotein A3, 37,000–38,000 daltons; pH at isoelectric point (pI) 4.5–5.0. Glycoproteins A2 and A3 were electroeluted and used to prepare a monospecific antiserum that identified proteins A1, A2, and A3 in immunoblots of crude surfactant obtained from dog lung lavage. This antiserum precipitated several proteins from in vitro translated canine lung poly(A)+ mRNA; proteins of 27,000 daltons, pI 5.0, and 28,000 daltons, pI 4.8–5.0, which precisely comigrated with proteins A1 from canine surfactant. Cotranslational processing of the primary translation products by canine pancreatic microsomal membranes resulted in larger proteins of 31,000–34,000 daltons, pI 4.8–5.0. Treatment of these processed forms of glycoprotein A with endoglycosidase F, to remove N-linked carbohydrate, resulted in proteins of 27,000–28,000 daltons which precisely comigrated with surfactant protein A1. These observations demonstrate that the polypeptide precursors to the glycoproteins A complex are extensively modified by addition of asparagine N-linked complex carbohydrate and are subsequently secreted as glycoproteins A2 and A3.
Hypoxia-induced activation in small isolated pulmonary arteries from the cat
Authors: Madden J. A. , Dawson C. A. , Harder D. R.
Published: December 2017

Effects of hypoxia on force development and membrane potential were studied in isolated small (less than 300 microns diam) and large (greater than 500 microns diam) pulmonary arteries from cats. There was a consistent and reproducible hypoxic constrictor response in small pulmonary arteries that began at PO2 values between 350 and 300 Torr and reached a maximum at PO2 between 50 and 30 Torr. In the small artery smooth muscle cell the membrane potential, which was -51 +/- 1.4 mV at a PO2 of 400 Torr, was depolarized to -37 +/- 2 mV at a PO2 of 50 Torr. In contrast, larger arteries did not exhibit significant hypoxic constriction or depolarization upon exposure to low PO2. Constriction in small arteries was not blocked by phentolamine. Treatment with a low dose of indomethacin (10(-9) M) augmented the response; however, a larger dose of indomethacin (10(-3) M) blocked the constriction to hypoxia but not to 30 mM KCl. Depolarization during hypoxia was not blocked by ouabain. Results of this study suggest that the hypoxic response of these isolated small pulmonary vessels may be like that seen in the intact lung. Furthermore, these data suggest that hypoxic vasoconstriction may be mediated by electrical events occurring at the pulmonary arterial muscle cell membrane either directly or via mediators released from the vessel wall.
Free, glucuronide, and sulfate catecholamines in the rat: effect of hypoxia
Authors: Claustre J. , Favre R. , Cottet-Emard J. M. , Peyrin L.
Published: December 2017

The formation and excretion of conjugated catecholamines (CA) was studied in conscious rats after sympathetic stimulation by hypoxia (5.5–6% O2, 4 h). Hypoxia induced a rapid and intense increase of free epinephrine (E, X 12) and norepinephrine (NE, X 6) but only a limited enhancement of free dopamine (DA, X 2). Sulfate conjugates of E and NE had kinetics similar to the free forms, while glucuronides were only moderately and lately altered. In contrast to free and sulfated DA, DA glucuronide, the major plasma conjugate, was decreased (-25%). This result suggests that DA glucuronide, unlike other CA conjugates, is not related to detoxication but might supply a CA precursor. Urinary conjugates badly reflected plasma conjugates. In normoxic controls, CA conjugates prevailed in the plasma, whereas the free amines prevailed in the urine. Hypoxia increased mainly the excretion of E and NE glucuronide but not of the free amines. Urinary DA, free or conjugated, was decreased (-25%), a result in keeping with plasma DA glucuronide only. The poor relations between plasma and urine catecholamines pinpoint the importance of the kidney in CA handling.
Calcium uptake in mitochondria from different skeletal muscle types
Authors: Sembrowich W. L. , Quintinskie J. J. , Li G.
Published: December 2017

The kinetics of calcium (Ca2+) uptake have been studied in mitochondria isolated from the different types of skeletal muscle. These studies demonstrate that the Ca2+ uptake properties of skeletal mitochondria are similar to those from liver and cardiac mitochondria. The Ca2+ carriers apparently have a high affinity for Ca2+ (Michaelis constants in the microM range). The relationship between Ca2+ uptake and initial Ca2+ concentration (10(-5) to 10(-7) M) is sigmoid in all mitochondria from the different skeletal muscle types suggesting that the uptake process is cooperative. Hill plots reveal coefficients of approximately 2 for mitochondria from fast-twitch muscle and 3.5 for slow-twitch muscle, adding further evidence to the concept that the uptake process is cooperative. An analysis of the potential role of mitochondria in the sequestration of Ca2+ during muscular contraction demonstrated that mitochondria from slow-twitch muscle of both rats and rabbits can potentially account for 100% of the relaxation rate at a low frequency of stimulation (5 Hz). In fast-twitch muscle, the mitochondria appear unable to play a significant role in muscle relaxation, particularly at stimulation frequencies that are considered in the normal physiological range. In summary, it appears that Ca2+ uptake by mitochondria from slow-twitch skeletal muscle has kinetic characteristics which make it important as a potential regulator of Ca2+ within the muscle cell under normal physiological conditions.
Respiration of conscious kittens in acute hypoxia and effect of almitrine bismesylate
Authors: McCooke H. B. , Hanson M. A.
Published: December 2017

Respiration was measured noninvasively in conscious kittens at an ambient temperature of 28–32 degrees C. Inspired O2 fraction (FIO2) was reduced abruptly from 0.21 to 0.12, 0.10, or 0.08 for 5 min on the day of birth and then on days 4, 7, 14, and 28. The ventilatory response to hypoxia was biphasic, as reported previously in anesthetized kittens, with minute ventilation (VE) increasing in the first minute and then falling towards control over the next 4 min. The fall in VE was due to a consistent fall in tidal volume, the changes in frequency during the second phase being more variable. The size of the first phase of the response increased up to 14 days, but the time at which the peak increase in VE occurred was not correlated with age. The degree of the secondary fall in VE was similar at each age and at each FIO2 studied. The degree of the biphasic response was significantly reduced after administration of almitrine (2 mg/kg ip) on days 1 and 4, but almitrine did not affect the response in older kittens.
Regulation of increase in anastomotic blood flow following pulmonary arterial occlusion
Authors: Jindal S. K. , Lakshminarayanan S. , Kirk W. , Butler J.
Published: December 2017

We have previously shown that there is an acute increase in anastomotic bronchial blood flow (Qbr) after pulmonary arterial obstruction in dogs. We examined the role of arachidonic acid metabolites in mediating this increase. The left lower lobe (LLL) was isolated and perfused (zone 2) with autologous blood in open-chested anesthetized dogs (n = 19). Qbr was measured from the amount of blood that overflowed from the closed vascular circuit of the suspended LLL and changes in its weight. In the control animals, there was a prompt and significant increase in Qbr following pulmonary arterial obstruction. Pretreatment with indomethacin (n = 6) or sodium salicylate (n = 4) almost completely blocked this rise in Qbr. Following pulmonary arterial occlusion, there was a rise in both thromboxane and a prostacyclin metabolite (6-keto-PGF1 alpha) in the blood of the pulmonary circulation of the LLL, although the 6-keto-PGF1 alpha rose relatively more. Pretreatment with indomethacin caused a fall in both thromboxane and prostacyclin levels (n = 3), which no longer rose after pulmonary arterial occlusion. These findings suggested that the balance of the vasodilator (prostacyclin) and vasoconstrictor (thromboxane) prostaglandins may play an important role in mediating the rise in Qbr that follows pulmonary arterial obstruction.
Segmental pulmonary vascular resistance in progressive hydrostatic and permeability edema
Authors: Wang C. G. , Hakim T. S. , Michel R. P. , Chang H. K.
Published: December 2017

We used the in situ blood-perfused left lower lobe preparation of the dog to examine the effect of hydrostatic and permeability edema on the slope and intercept of the vascular pressure-flow (P/Q) relationship and on the longitudinal distribution of vascular resistance with the arterial and venous occlusion technique. Hydrostatic edema (HE) was induced by raising the venous pressure, and permeability edema (PE) was induced with alpha-naphthylthiourea. When the hematocrit (Hct) of the perfusate was kept normal (approximately 40%), HE had no significant effect on either the slope or the intercept of the P/Q relationship or on the distribution of vascular resistance. PE caused a small increase in the intercept of the P/Q relationship and a small rise in the resistance of the vessels in the middle segment. In another series of HE experiments in which Hct was allowed to increase during edema formation, there was a marked increase in vascular resistance. We conclude that edema per se does not increase vascular resistance significantly and that the increases in vascular resistance which were observed previously by other investigators in the isolated lungs may be due to increases in blood hematocrit.
Comparison of thermal responses between rest and leg exercise in water
Authors: Toner M. M. , Sawka M. N. , Holden W. L. , Pandolf K. B.
Published: December 2017

This study examined both the thermal and metabolic responses of individuals in cool (30 degrees C, n = 9) and cold (18 degrees C, n = 7; 20 degrees C, n = 2) water. Male volunteers were immersed up to the neck for 1 h during both seated rest (R) and leg exercise (LE). In 30 degrees C water, metabolic rate (M) remained unchanged over time during both R (115 W, 60 min) and LE (528 W, 60 min). Mean skin temperature (Tsk) declined (P less than 0.05) over 1 h during R, while Tsk was unchanged during LE. Rectal (Tre) and esophageal (Tes) temperatures decreased (P less than 0.05) during R (delta Tre, -0.5 degrees C; delta Tes, -0.3 degrees C) and increased (P less than 0.05) during LE (delta Tre, 0.4 degrees C; Tsk, 0.4 degrees C). M, Tsk, Tre, and Tes were higher (P less than 0.05) during LE compared with R. In cool water, all regional heat flows (leg, chest, and arm) were generally greater (P less than 0.05) during LE than R. In cold water, M increased (P less than 0.05) over 1 h during R but remained unchanged during LE. Tre decreased (P less than 0.05) during R (delta Tre, -0.8 degrees C) but was unchanged during LE. Tes declined (P less than 0.05) during R (delta Tes, -0.4 degrees C) but increased (P less than 0.05) during LE (delta Tes, 0.2 degrees C). M, Tre, and Tes were higher (P less than 0.05), whereas Tsk was not different during LE compared with R at 60 min.
Effect of body orientation on regional lung expansion in dog and sloth
Authors: Hoffman E. A. , Ritman E. L.
Published: December 2017

Page 481: E. A. Hoffman and E. L. Ritman. “Effect of body orientation on regional lung expansion in dog and sloth.” Pages 484 (right-hand column, third paragraph, third line), 485 (Fig. 5 legend, ninth line), and 489 (left-hand column, first paragraph, fifth and sixth lines): substitute cm lung height for ml lung height.
Pressure-flow relationships of endotracheal tubes during high-frequency ventilation
Authors: Gavriely N. , Solway J. , Loring S. H. , Butler J. P. , Slutsky A. S. , Drazen J. M.
Published: December 2017

We studied the pressure-flow relationships of various endotracheal tubes (ETT) at frequencies (f) and tidal volumes (VT) in the range used for high-frequency ventilation (HFV) (f: 2–32 Hz, VT: 15–100 ml). Sinusoidal flows were applied to ETT inserted into a rigid bottle or into the tracheae of three anesthetized paralyzed dogs, while pressure fluctuations were measured both proximal and distal to the ETT. The pressure drops in the ETT were nonlinearly related to the peak flow rate and were VT dependent, suggesting that turbulent frictional head loss and convective acceleration were important. The pressure drops measured in vitro were found to be in good agreement with the predictions of a nonlinear oscillatory pressure-flow equation (derived herein), which incorporate the effects of turbulent frictional losses, convective acceleration, inertance, and compliance. The pressure drops measured in situ were 30–50% higher than with the corresponding f-VT combinations in vitro. Possible explanations of these differences are junctional losses at the tip of the ETT or the nonrigid character of the trachea.
Treadmill vs. floor walking: kinematics, electromyogram, and heart rate
Authors: Murray M. P. , Spurr G. B. , Sepic S. B. , Gardner G. M. , Mollinger L. A.
Published: December 2017

To identify the degree of difference between treadmill and floor walking, kinematic, electromyographic (EMG), and heart rate measurements were recorded in seven normal female subjects during walking at three speeds on the treadmill and on the floor. During treadmill walking, subjects tended to use a faster cadence and shorter stride length than during floor walking. In addition the displacements of the head, hip, and ankle in the sagittal plane showed statistically significant differences between floor and treadmill walking. Average EMG activity was usually greater on the treadmill than on the floor; however, this difference was only significant for the quadriceps. Heart rate was significantly higher during fast treadmill walking than floor walking. In general, treadmill walking was not found to differ markedly from floor walking in kinematic measurements or EMG patterns.
Effects of elastase and cigarette smoke on alveolar epithelial permeability
Authors: Schmid R. P. , Wangensteen D. , Hoidal J. , Gosnell B. , Niewoehner D.
Published: December 2017

To determine whether instilled porcine pancreatic elastase (PPE) increases alveolar epithelial permeability, we measured alveolar epithelium permeability X surface area (PS) for [14C]sucrose and 125I-bovine serum albumin (125I-BSA) in isolated perfused lungs from hamsters previously exposed to PPE and/or cigarette smoke. Saline (0.5 ml) with 0, 5, or 20 units PPE was instilled intratracheally in anesthetized hamsters. Those exposed to smoke for 4–6 wk received 0 or 5 units; PS was measured 3 h later. Nonsmokers received 0, 5, or 20 units; PS was measured 3 h, 24 h, or 5 days later. Control PS values were (cm3/s X 10(-4), +/- SE) 0.84 +/- 0.11 for sucrose and 0.030 +/- 0.006 for BSA. Three and 24 h following 20 units PPE, (PS)sucrose was twice the control valve. (PS)BSA was four times control at 3 h but not significantly increased at 24 h. Five days after PPE both were back to control levels. Five units PPE or smoke exposure alone caused no PS changes. Smoke exposure and 5 units PPE caused (PS)sucrose to increase markedly (1.85 +/- 0.32); (PS)BSA was not significantly increased (0.076 +/- 0.026). Thus instilled PPE causes reversible increases in alveolar epithelial PS; cigarette smoking potentiates this effect.
Blood viscosity responses to maximal exercise in endurance-trained and sedentary female subjects
Authors: Martin D. G. , Ferguson E. W. , Wigutoff S. , Gawne T. , Schoomaker E. B.
Published: December 2017

To assess whether the rheological properties of blood might be altered by exercise, we measured whole blood viscosity, plasma viscosity, and its components in healthy female subjects before, immediately after, and 1 h after maximal upright exercise using the Bruce graded exercise protocol. Forty-seven female subjects (15 sedentary, 14 who ran 5–15 miles/wk, and 18 who ran greater than 50 miles/wk), ages 18–43 yr, were evaluated. Whole blood viscosity, measured with a cone and plate viscometer, increased an average of 12.6% with exercise. The increase was greater than can be attributed to the observed 8.9% increase in hematocrit alone due to a coincident increase in plasma protein concentration. However, plasma viscosity did not rise to the degree expected, likely due to a disproportionate observed loss of fibrinogen from the protein pool. These changes were independent of conditioning level or aerobic capacity. In this cross-sectional study, there appears to be no adaptive adjustment in females to physical conditioning that results in changes in blood viscosity.
Changes in heart rate during breathing interrupted by recurrent apneas in humans
Authors: Findley L. J. , Farkas G. A. , Rochester D. F.
Published: December 2017

Heart rate varies with breathing patterns, especially in sleep apnea. To assess the effects on heart rate of recurrent apneas interrupting tidal breathing, we studied five normal awake male subjects. These subjects voluntarily changed their breathing pattern from regular tidal breathing to tidal breathing interrupted by breath holding at end expiration. This recurrent apneic breathing pattern did not change mean heart rate but increased its variance significantly. In addition, the variations in heart rate formed a cyclic pattern of oscillation with a mean cycle length identical to both arterial O2 saturation (SaO2) (R = 0.95; P less than 0.01) and ventilation (R = 0.92; P less than 0.01). Cyclic changes in either SaO2 or ventilation reproduced the oscillatory patterns of heart rate seen with tidal breathing interrupted by multiple apneas, but the amplitude of the variance in heart rate was smaller. Finally, preventing the cyclic declines in SaO2 with supplemental O2 did not significantly alter the heart rate changes seen in tidal breathing interrupted by apneas.
Transpulmonary passage of venous air emboli
Authors: Butler B. D. , Hills B. A.
Published: December 2017

Twenty-seven paralyzed anesthetized dogs were embolized with venous air to determine the effectiveness of the pulmonary vasculature for bubble filtration or trapping. Air doses ranged from 0.05 to 0.40 ml X kg-1 X min-1 in 0.05-ml increments with ultrasonic Doppler monitors placed over arterial vessels to detect any microbubbles that crossed the lungs. Pulmonary vascular filtration of the venous air infusions was complete for the lower air doses ranging from 0.05 to 0.30 ml X kg-1 X min-1. When the air doses were increased to 0.35 ml X kg-1 X min-1, the filtration threshold was exceeded with arterial spillover of bubbles occurring in 50% of the animals and reaching 71% for 0.40 ml X kg-1 X min-1. Significant elevations were observed in pulmonary arterial pressure and pulmonary vascular resistance. Systemic blood pressure and cardiac output decreased, whereas left ventricular end-diastolic pressure remained unchanged. The results indicate that the filtration of venous bubbles by the pulmonary vasculature was complete when the air infusion rates were kept below a threshold value of 0.30 ml X kg-1 X min-1.
Extracellular carbonic anhydrase of skeletal muscle associated with the sarcolemma
Authors: Geers C. , Gros G. , Gartner A.
Published: December 2017

We report here 1) the synthesis and properties of a new macromolecular carbonic anhydrase inhibitor, Prontosil-dextran, 2) its application to determine the localization of a previously described extracellular carbonic anhydrase in skeletal muscle, and 3) the application of a recently published histochemical technique using dansylsulfonamide to the same problem. Stable macromolecular inhibitors of molecular weights of 5,000, 100,000 and 1,000,000 were produced by covalently coupling the sulfonamide Prontosil to dextrans. Their inhibition constants towards bovine carbonic anhydrase II are 1–2 X 10(-7) M. The Prontosil-dextrans, PD 5,000, PD 100,000, and PD 1,000,000, were used in studies of the washout of H14CO3-) from the perfused rabbit hindlimb. This washout is slow due to the presence of an extracellular carbonic anhydrase and can be markedly accelerated by PD 5,000 but not by PD 100,000 and PD 1,000,000. Since PD 5,000 is accessible to the entire extracellular space and PD 100,000 and PD 1,000,000 are confined to the intravascular space, we conclude that the extracellular carbonic anhydrase of skeletal muscle is located in the interstitium. The histochemical studies show a strong staining of the sarcolemma of the muscle fibers with high oxidative capacity. It appears likely, therefore, that the extracellular carbonic anhydrase of skeletal muscle is associated with muscle plasma membranes with its active site directed toward the interstitial space.
Plasma volume changes in middle-aged male and female subjects during marathon running
Authors: Myhre L. G. , Hartung G. H. , Nunneley S. A. , Tucker D. M.
Published: December 2017

Circulatory fluid shifts were studied in middle-aged runners (6 males and 5 females, ages 32–58 yr) during a 42.2-km marathon race run in mild weather (dry-bulb temperature = 17.5–20.4 degrees C). Running times for the subjects were 3:12–4:40 (mean values were 3:34 for males and 4:10 for females). Venous blood samples were taken without stasis in all subjects seated at rest before the start of the race and within 3 min of finishing; eight of the subjects also paused for samples at 6 and 27 km during the race. At 6 km, body weight loss averaged less than 1%, whereas plasma volume (PV) had decreased by 6.5% in male subjects and 8.6% in female subjects. By the end of the race, hypohydration had reached 3.2% in male subjects and 2.9% in female subjects, but PV in both groups remained stable. Sweat rates during the race averaged 545 and 429 g X m-2 X h-1 for male and female subjects, respectively, with ad lib. water intake replacing 21–72% of fluid loss. Increases in plasma protein concentration throughout the race reflected the observed initial decrease in PV. The interpretation of PV responses to exercise and/or hypohydration is critically dependent on selection of base-line conditions; we were able to control for posture-exercise effects by treating the early exercise (6 km) sample as the base line for examining the effects of later fluid loss. Under these conditions, the vascular compartment resisted volume depletion. The ability to maintain stable PV can be explained in part by relationships among oncotic and hydrostatic pressures in the intra- and extravascular fluid compartments.
Pleural liquid pressure in dogs measured using a rib capsule
Authors: Wiener-Kronish J. P. , Gropper M. A. , Lai-Fook S. J.
Published: December 2017

We have developed a minimally invasive method for measuring the hydrostatic pressure in the pleural space liquid. A liquid-filled capsule is bonded into a rib and a small hole is cut in the parietal pleura to allow direct communication between the liquid in the capsule and the pleural space. The pressure can be measured continuously by a strain gauge transducer connected to the capsule. The rib capsule does not distort the pleural space or require removal of intercostal muscle. Pneumothoraces are easily detected when they occur inadvertently on puncturing the parietal pleura. We examined the effect of height on pleural pressure in 15 anesthetized spontaneously breathing dogs. The vertical gradients in pleural pressure were 0.53, 0.42, 0.46, and 0.23 cmH2O/cm height for the head-up, head-down, supine, and prone body positions, respectively. These vertical gradients were much less than the hydrostatic value (1 cmH2O/cm), indicating that the pleural liquid is not in hydrostatic equilibrium. In most body positions the magnitudes of pleural liquid pressure interpolated to midchest level were similar to the mean transpulmonary (surface) pressure determined postmortem. This suggests that pleural liquid pressure is closely related to the lung static recoil.
Small-animal traumatizer
Authors: Francis R. S.
Published: December 2017

Clinical research, particularly among traumatized musculoskeletal patients, has been greatly inhibited by a lack of uniformity in the intensity of the injury. That is, few patients present identical injuries with respect to intensity and degree of soft tissue damage. Hence, researchers have gone to the experimental animal to achieve uniformity to the wound. Few studies, however, have reported effective methods of uniform traumatization. A small-animal traumatizer was developed at Brigham Young University that has proved reliable in producing a uniform contusion of 177 mm2 on the lateral thigh of the anesthetized experimental animal. If the investigator seeks an experimentally induced hematoma that approximates contusions seen clinically, one that is unvarying in every sample, something not available in traumatized patients, the small-animal traumatizer may be an important addition to your laboratory.
Correlation between plasma fibronectin level and experimental rat heat stress mortality
Authors: DuBose D. A. , McCreary J. , Sowders L.
Published: December 2017

Reticuloendothelial system (RES) clearance function correlates with the mortality rate associated with stresses that can induce shock. Likewise, experimental rat heat stress (ERHS) mortality rate is altered by modulation of RES function. Since plasma fibronectin (PF) in many instances appears to mediate in vivo phagocytosis by the RES, the relationship between mean plasma fibronectin level (MPFL) and ERHS mortality was examined. A comparison of MPFLs prior to ERHS revealed that rats which ultimately comprised the survival group had a MPFL of 269.0 +/- 11.2 micrograms/ml, whereas that of the nonsurvivors was 252.9 +/- 11.9 micrograms/ml. Both groups had elevated MPFLs up to 12 h following ERHS. However, after this time, MPFL began to decline. The decline was more severe for the nonsurvivors, with MPFLs at 15, 18, and 20.3 h significantly (P less than 0.01) lower than the values for the survival group. Even the lowest MPFL (256.0 +/- 30.7 micrograms/ml) noted for the survival group was still significantly (P less than 0.01) higher than the value (159.3 +/- 13.3 micrograms/ml) determined for agonal samples collected from nonsurvivors. Furthermore, grouping rats according to their preheat PF level demonstrated that rats with levels exceeding 300 micrograms/ml had significantly (P less than 0.05) reduced mortality rates (12.5 vs. 51.3%) compared with rats with levels below this value. It was concluded that elevated PF levels prior to ERHS correlated with thermotolerance.
Effects of detraining on responses to submaximal exercise
Authors: Coyle E. F. , Martin W. H. , Bloomfield S. A. , Lowry O. H. , Holloszy J. O.
Published: December 2017

Seven endurance-trained subjects were studied 12, 21, 56, and 84 days after cessation of training. Heart rate, ventilation, respiratory exchange ratio, and blood lactate concentration during submaximal exercise of the same absolute intensity increased (P less than 0.05) progressively during the first 56 days of detraining, after which a stabilization occurred. These changes paralleled a 40% decline (P less than 0.001) in mitochondrial enzyme activity levels and a 21% increase in total lactate dehydrogenase (LDH) activity (P less than 0.05) in trained skeletal muscle. After 84 days of detraining, the experimental subjects' muscle mitochondrial enzyme levels were still 50% above, and LDH activity was 22% below, sedentary control levels. The blood lactate threshold of the detrained subjects occurred at higher absolute and relative (i.e., 75 +/- 2% vs. 62 +/- 3% of maximal O2 uptake) exercise intensities in the subjects after 84 days of detraining than in untrained controls (P less than 0.05). Thus it appears that a portion of the adaptation to prolonged and intense endurance training that is responsible for the higher lactate threshold in the trained state persists for a long time (greater than 85 days) after training is stopped.
Headache at high altitude is not related to internal carotid arterial blood velocity
Authors: Reeves J. T. , Moore L. G. , McCullough R. E. , McCullough R. G. , Harrison G. , Tranmer B. I. , Micco A. J. , Tucker A. , Weil J. V.
Published: December 2017

The cause of headache in persons going to high altitude is unknown. Relatively severe hypoxemia in susceptible subjects could induce large increases in cerebral blood flow that then could initiate the headache. Thus we measured noninvasively, by Doppler ultrasound, changes in internal carotid arterial blood velocity (velocity) in 12 subjects in Denver (1,600 m) and repeatedly up to 7 h at a simulated altitude of 4,800 m (barometric pressure = 430 Torr). Six subjects, selected because of prior history of high-altitude headache, developed comparatively severe headache at 4,800 m, and four subjects, without such history, remained well. Two subjects developed moderate headache. Velocity at 4,800 m did not correlate with symptom development, arterial O2 saturation, or end-tidal PCO2. Also, neither velocity nor blood pressure was consistently elevated above the Denver base-line values. During measurements of hypercapnic ventilatory response in Denver, velocity increased linearly with end-tidal PCO2, confirming that our Doppler method could demonstrate an increase. Also, 30 min of isocapnic or poikilocapnic hypoxia caused small increases in velocity (+8 and +6%) during the base-line measurement at low altitude. Although even a small increase in cerebral perfusion could contribute to headache symptoms at high altitude, cerebral blood flow does not appear to play a primary role.
Tonic beta-sympathetic activity in the lung periphery in anesthetized dogs
Authors: Weinmann G. G. , Spannhake E. W. , Bromberger-Barnea B. , Menkes H. A.
Published: December 2017

The present study was undertaken to determine whether beta-adrenoceptors could be physiologically detected in the lung periphery and whether they were under tonic stimulation in the resting state in anesthetized dogs. A fiberoptic bronchoscope was wedged in a sublobar segment of lung in anesthetized male mongrel dogs for measurement of resistance through the collateral system (Rcs). beta-Agents were delivered locally as aerosols through the bronchoscope, and the response was evaluated by changes in Rcs. Distilled water alone produced a mean increase of 8.5 +/- 2.43% (SE) in Rcs at 2 min in six dogs, whereas dl-isoproterenol produced a mean decrease of 8.9 +/- 2.10% (P less than 0.03), thus demonstrating the presence of submaximally stimulated beta-receptors. To test whether the beta-receptors were under tonic stimulation, we compared the effect of aerosolized d- and dl-propranolol in 5 dogs. d-Propranolol that lacks significant beta-blocking activity and dl-propranolol both produced large transient increases in Rcs. However, with d-propranolol, Rcs had returned to base line at 15 min, whereas with dl-propranolol Rcs remained elevated at a mean of 20% above base line for greater than 2 h (P less than 0.01). Local timolol aerosol also produced a sustained increase in Rcs. After pretreatment with reserpine or after bilateral adrenalectomy, both d- and dl-propranolol still produced large transient increases in Rcs, but dl-propranolol no longer produced a sustained increase. Neither isoproterenol nor atropine affected Rcs in the presence of dl-propranolol, nor did pretreatment with atropine affect the response of Rcs to dl-propranolol.
Plasma-lymph exchange and interstitial distribution volumes of charged macromolecules in the lung
Authors: Parker J. C. , Gilchrist S. , Cartledge J. T.
Published: December 2017

The plasma-lymph exchange of two lactate dehydrogenase (LDH) isozymes (4.2 nM) of different molecular charge between plasma (CP) and lung lymph (CL), their initial clearances across the capillary wall, and their extravascular distribution volumes were studied in dog lungs at control and increased left atrial pressures (Pla = 23.3 +/- 2.1 cmH2O). The anionic LDH 1 [isoelectric point (pI) = 5.0] exhibited a more rapid plasma decay compared with cationic LDH 5 (pI = 7.9) after bolus injection but was maintained relatively constant in several experiments using a constant infusion. The mean 10- to 12-min lung tissue clearances were 40% higher for LDH 5 than LDH 1 at control Pla and 120% higher at increased Pla. The CL/CP ratios of the anionic LDH 1 were consistently higher at 4–5 h after simultaneous injection than those of cationic LDH 5. However, the extravascular distribution volumes of LDH 5 were significantly higher in lymph equivalents than those of LDH 1 at 4 h in both Pla groups. Fixed negative charges located on endothelial cells, basement membrane, and interstitial matrix could explain the observed differences between LDH isozymes in CL/CP ratios, tissue uptake, and extra-vascular distribution volumes by the ionic interaction of LDH 5 with these negative change sites which would retard the plasma-lymph transport and enhance the extravascular distribution volume and initial clearance of these cationic macromolecules.
Biochemical response to chronic shortening in unloaded soleus muscles
Authors: Jaspers S. R. , Fagan J. M. , Tischler M. E.
Published: December 2017

One leg of tail-casted suspended rats was immobilized in a plantar-flexed position to test whether chronic shortening of posterior leg muscles affected the metabolic response to unloading. The immobilized plantaris and gastrocnemius muscles of these animals showed approximately 20% loss of muscle mass in contrast to simply a slower growth rate with unloading. Loss of mass of the soleus muscle during suspension was not accentuated by chronic shortening. Although protein degradation in the isolated soleus muscle of the plantar-flexed limb was slightly faster than in the contralateral free limb, this difference was offset by faster synthesis of the myofibrillar protein fraction of the chronically shortened muscle. Total adenine nucleotides were 17% lower (P less than 0.005) in the chronically shortened soleus muscle following incubation. Glutamate, glutamine, and alanine metabolism showed little response to chronic shortening. These results suggest that, in the soleus muscle, chronic shortening did not alter significantly the metabolic responses to unloading and reduced activity.
Collateral sources of costal and crural diaphragmatic blood flow
Authors: Lockhat D. , Magder S. , Roussos C.
Published: December 2017

We measured the contribution of aortic, internal mammary, and intercostal arteries to the blood flow to the costal and crural segments of the diaphragm and other respiratory muscles in seven dogs breathing against a fixed inspiratory elastic load. We used radiolabeled microspheres to measure the blood flow with control circulation, occlusion of the aorta distal to the left subclavian artery, combined occlusion of the aorta and both internal mammary arteries, and occlusion of internal mammary arteries alone. With occlusion of the aorta distal to the left subclavian artery, blood flow to the crural diaphragm decreased from 40.3 to 23.5 ml . min-1 X 100 g-1, whereas costal flow did not change significantly (from 41.7 to 38.1 ml . min-1 . 100 g-1). Blood flows to the sternomastoid and scalene muscles (above the occlusion) increased by 200 and 340%, respectively, whereas flows to the other respiratory muscles did not change significantly. Blood flows to organs above the occlusion either remained unchanged or increased, whereas flows to those below the occlusion all decreased. When the internal mammary artery was also occluded, flows to the crural segment decreased further to 12.1 and costal flow decreased to 20.4 ml X min-1 X 100 g-1. Internal mammary arterial occlusion alone in two dogs had no effect on diaphragmatic flow. In conclusion, intercostal collateral vessels are capable of supplying a significant proportion of blood flow to both segments of the diaphragm but the costal segment is better served than the crural segment.
Calcium secretion in canine tracheal mucosa
Authors: Al-Bazzaz F. J. , Jayaram T.
Published: December 2017

Calcium (Ca) affects many cellular functions of the respiratory tract mucosa and might alter the viscoelastic properties of mucus. To evaluate Ca homeostasis in a respiratory epithelium we investigated transport of Ca by the canine tracheal mucosa. Mucosal tissues were mounted in Ussing-type chambers and bathed with Krebs-Henseleit solution at 37 degrees C. Unidirectional fluxes of 45Ca were determined in tissues that were matched by conductance and short-circuit current (SCC). Under short-circuit conditions there was a significant net Ca secretion of 1.82 +/- 0.36 neq . cm-2 . h-1 (mean +/- SE). Under open-circuit conditions, where the spontaneous transepithelial potential difference could attract Ca toward the lumen, net Ca secretion increased significantly to 4.40 +/- 1.14 compared with 1.54 +/- 1.17 neq . cm-2 . h-1 when the preparation was short-circuited. Addition of a metabolic inhibitor, 2,4-dinitrophenol (2 mM in the mucosal bath), decreased tissue conductance and SCC and slightly decreased the unidirectional movement of Ca from submucosa to lumen. Submucosal epinephrine (10 microM) significantly enhanced Ca secretion by 2.0 +/- 0.63 neq . cm-2 . h-1. Submucosal ouabain (0.1 mM) failed to inhibit Ca secretion. The data suggest that canine tracheal mucosa secretes Ca; this secretory process is augmented by epinephrine or by the presence of a transepithelial potential difference as found under in vivo conditions.
Increased cardiac output increases shunt: role of pulmonary edema and perfusion
Authors: Breen P. H. , Schumacker P. T. , Sandoval J. , Mayers I. , Oppenheimer L. , Wood L. D.
Published: December 2017

In low-pressure pulmonary edema increased cardiac output (QT) increases shunt (Qs/QT); we tested whether the mechanism is an increase in extravascular lung water in turn mediated by the accompanying increase in microvascular pressure. In six pentobarbital sodium-anesthetized dogs ventilated with O2 we administered oleic acid into the right atrium. From base line to 2 h post-oleic acid we measured concurrent significant increases in Qs/QT (6–29%, O2 technique) and extravascular thermal volume (ETV, 2.6–7.1 ml/g dry intravascular blood-free lung wt, thermal-green dye indicator technique) that were stable by 90 min. Then, bilateral femoral arteriovenous fistulas were opened and closed in 30-min periods to cause reversible increases in QT and associated Qs/QT. When fistulas were open the time-averaged QT increased from 5.1 to 6.9 min (P less than 0.05), the simultaneous Qs/QT rose from 30.7 to 38.4% (P less than 0.05), but ETV did not increase. We conclude that increasing lung edema does not account for our rise in Qs/QT when QT increased.
Influence of testosterone on ventilation and chemosensitivity in male subjects
Authors: White D. P. , Schneider B. K. , Santen R. J. , McDermott M. , Pickett C. K. , Zwillich C. W. , Weil J. V.
Published: December 2017

There is increasing evidence that men have higher ventilatory responses to chemical stimuli than age-matched women and that certain disorders of respiratory rhythmicity, particularly sleep apnea, occur more commonly in men. Accordingly, we studied the influence of the male hormone, testosterone, on the control of breathing. Twelve hypogonadal males were studied at least 30 (mean +/- SE: 69.7 +/- 8.9) days after discontinuing testosterone replacement and again following hormone administration. In each subject plasma testosterone concentration, metabolic rate [O2 consumption (VO2) and CO2 production (VCO2)], minute ventilation (VE), and chemosensitivity [hypoxic (HVR) and hypercapnic (HCVR) ventilatory responses] were determined on and off hormone replacement. With testosterone administration VO2 increased from 248 +/- 15 to 276 +/- 18 ml/min (P less than 0.05), with VCO2 showing a similar but nonsignificant trend. This was associated with an increase in VE from 8.41 +/- 0.78 to 9.91 +/- 0.75 l/min (P less than 0.05) but no change in PCO2. The HVR, expressed as A, increased 44% with hormone replacement from a value of 122 +/- 23 to 176 +/- 28 (P less than 0.01), whereas the HCVR was minimally affected by testosterone administration. These findings may in part explain the previously described differences between male and female subjects in hypoxic sensitivity.
Hindlimb muscular contraction reflexly decreases total pulmonary resistance in dogs
Authors: Kaufman M. P. , Rybicki K. J. , Mitchell J. H.
Published: December 2017

We have previously shown that contraction of the gracilis muscles of anesthetized dogs reflexly relaxes tracheal smooth muscle. We have also found that electrical stimulation of these afferents decreases total pulmonary resistance (TPR), a calculation that provides a functional index of airway caliber. Despite these findings, we have yet to show that muscular contraction reflexly decreases TPR. Therefore, in 11 alpha-chloralose-anesthetized dogs, we contracted the hindlimb muscles by electrically stimulating the L6-L7 ventral roots while measuring TPR breath by breath. We found that static contraction decreased TPR from 12.6 +/- 1.1 to 10.4 +/- 0.9 cmH2O X l-1 X s (P less than 0.05). This decrease was reflex in origin because it was prevented by section of the spinal roots innervating the working hindlimb. Repetitive twitch contractions (5 Hz) also reflexly decreased TPR, but the effect was smaller than that evoked by static contraction. The reflex decreases in TPR evoked by contraction were unaffected by propranolol but were abolished by atropine. We conclude that muscular contraction dilates the airways by a reflex mechanism whose efferent arm consists of a withdrawal of cholinergic input to airway smooth muscle.
Effects of high-frequency and conventional ventilation on the premature lamb lung
Authors: Solimano A. , Bryan C. , Jobe A. , Ikegami M. , Jacobs H.
Published: December 2017

Twelve sets of twin lambs were delivered prematurely by cesarean section at 133–136 days gestational age and ventilated for 3 h with either high-frequency oscillation (HFO) or conventional mechanical ventilation (CMV). Blood gases and pH values were monitored at 30-min intervals, and ventilator settings were adjusted to maintain CO2 partial pressure (PCO2) values within the normal range. There were no differences in the sequential blood gas or pH values between the HFO or CMV lambs. Mean airway pressures (MAP) between 8.0 and 20.4 cmH2O were required, indicating lung disease of variable severity in the lambs. The bidirectional protein leak from the vascular space to the airways and alveoli and vice versa was measured with radiolabeled albumins given by intravascular injection and with fetal lung fluid at birth. The albumin leaks in both directions increased as MAP required to normalize PCO2 increased, but the degree of leak was independent of type of ventilation. Pathological findings of epithelial necrosis and hyaline membranes occurred to a similar extent in lung sections from both groups of lambs. In the HFO animals less phosphatidylcholine in the alveolar wash and more of a tracer dose of radiolabeled natural surfactant that had been given at birth became tissue associated. These results indicate a decrease in the initial secretion of surfactant and/or a stimulation of reuptake in the HFO animals. HFO did not protect the immature lung from the development of large protein leaks or the pathological changes of the respiratory distress syndrome.
Carbohydrate metabolism during and after exercise in rats: studies with radioglucose
Authors: Sonne B. , Galbo H.
Published: December 2017

Carbohydrate metabolism in exercise, including regulation of glucose production, was studied by isotope-dilution methods, and these were evaluated. Chronically catheterized rats were examined before, during, and after 45 min of running at either low (LIE) or moderate (MIE) intensity. Glucose production (Ra) and disappearance (Rd), as well as muscular glycogen breakdown (Gly), were estimated by primed constant infusions of [3–3H]- and [U-14 C]glucose, and pyruvate oxidation was estimated by sampling of expired 14CO2. During exercise, Ra increased faster than Rd and was, as were steady-state glucose concentration (G) and Gly, directly related to exercise intensity. During recovery Ra and G decreased rapidly, but after MIE, G showed a rebound increase. 14C estimates and chemical measurements sometimes disagreed. Methodological evaluation showed marked incorporation of label in glycogen, lipid, and protein at rest and mobilization of label during exercise. 14CO2 recovery in expired air ranged from only 50% at rest to 77% during MIE. In conclusion, during exercise, mobilization of hepatic glycogen is a primary event and not secondary to increased muscular demand. During and after exercise, plasma glycogen is not precisely controlled at euglycemic levels. Isotope methods may be used to study carbohydrate metabolism in exercising rats, but the results (especially 14C data) should be interpreted with caution.