bluuebunny/crossref_metadata_2025 huggingface dataset:
Methacholine-induced bronchoconstriction in rats: effects of intravenous vs. aerosol delivery
Authors: Peták Ferenc , Hantos Zoltán , Adamicza Ágnes , Asztalos Tibor , Sly Peter D.
Published: December 2017

Peták, Ferenc, Zoltán Hantos, Ágnes Adamicza, Tibor Asztalos, and Peter D. Sly. Methacholine-induced bronchoconstriction in rats: effects of intravenous vs. aerosol delivery. J. Appl. Physiol. 82(5): 1479–1487, 1997.—To determine the predominant site of action of methacholine (MCh) on lung mechanics, two groups of open-chest Sprague-Dawley rats were studied. Five rats were measured during intravenous infusion of MCh (iv group), with doubling of concentrations from 1 to 16 μg ⋅ kg−1⋅ min−1. Seven rats were measured after aerosol administration of MCh with doses doubled from 1 to 16 mg/ml (ae group). Pulmonary input impedance (Zl) between 0.5 and 21 Hz was determined by using a wave-tube technique. A model containing airway resistance (Raw) and inertance (Iaw) and parenchymal damping (G) and elastance (H) was fitted to the Zl spectra. In the iv group, MCh induced dose-dependent increases in Raw [peak response 270 ± 9 (SE) % of the control level; P < 0.05] and in G (340 ± 150%; P < 0.05), with no increase in Iaw (30 ± 59%) or H (111 ± 9%). In the ae group, the dose-dependent increases in Raw (191 ± 14%; P < 0.05) and G (385 ± 35%; P< 0.05) were associated with a significant increase in H (202 ± 8%; P < 0.05). Measurements with different resident gases [air vs. neon-oxygen mixture, as suggested (K. R. Lutchen, Z. Hantos, F. Peták,Á. Adamicza, and B. Suki. J. Appl. Physiol. 80: 1841–1849, 1996)] in the control and constricted states in another group of rats suggested that the entire increase seen in G during the iv challenge was due to ventilation inhomogeneity, whereas the ae challenge might also have involved real tissue contractions via selective stimulation of the muscarinic receptors.
Training improves endothelium-dependent vasodilation in resistance vessels of patients with heart failure
Authors: Katz Stuart D. , Yuen Jeannette , Bijou Rachel , Lejemtel Thierry H.
Published: December 2017

Katz, Stuart D., Jeannette Yuen, Rachel Bijou, and Thierry H. LeJemtel. Training improves endothelium-dependent vasodilation in resistance vessels of patients with heart failure. J. Appl. Physiol. 82(5): 1488–1492, 1997.—The effects of physical training on endothelium-dependent vasodilation in skeletal muscle resistance vessels were investigated in patients with heart failure. Forearm blood flows (ml ⋅ min−1 ⋅ 100 ml−1) in response to brachial arterial administration of acetylcholine (5 × 10−5 and 5 × 10−4 M at 1 ml/min) and nitroglycerin (5 × 10−6 and 5 × 10−5 M at 1 ml/min) were determined by strain-gauge venous occlusion plethysmography before and after 8 wk of daily handgrip exercise in 12 patients with chronic heart failure. After 8 wk of daily handgrip exercise, the vasodilatory responses to acetylcholine significantly increased from pretraining values, i.e., 16.6 ± 2.0 vs. 8.6 ± 1.3 ml ⋅ min−1 ⋅ 100 ml−1( P < 0.05) and 27.5 ± 1.5 vs. 14.6 ± 1.7 ml ⋅ min−1 ⋅ 100 ml−1( P < 0.05), respect- ively, whereas the vasodilatory responses to nitroglycerin did not change. Handgrip exercise training appears to specifically enhance endothelium-dependent vasodilation in the forearm skeletal muscle circulation of patients with heart failure.
Reflex tracheal smooth muscle contraction and bronchial vasodilation evoked by airway cooling in dogs
Authors: Pisarri Thomas E. , Giesbrecht Gordon G.
Published: December 2017

Pisarri, Thomas E., and Gordon G. Giesbrecht. Reflex tracheal smooth muscle contraction and bronchial vasodilation evoked by airway cooling in dogs. J. Appl. Physiol. 82(5): 1566–1572, 1997.—Cooling intrathoracic airways by filling the pulmonary circulation with cold blood alters pulmonary mechanoreceptor discharge. To determine whether this initiates reflex changes that could contribute to airway obstruction, we measured changes in tracheal smooth muscle tension and bronchial arterial flow evoked by cooling. In nine chloralose-anesthetized open-chest dogs, the right pulmonary artery was cannulated and perfused; the left lung, ventilated separately, provided gas exchange. With the right lung phasically ventilated, filling the right pulmonary circulation with 5°C blood increased smooth muscle tension in an innervated upper tracheal segment by 23 ± 6 (SE) g from a baseline of 75 g. Contraction began within 10 s of injection and was maximal at ∼30s. The response was abolished by cervical vagotomy. Bronchial arterial flow increased from 8 ± 1 to 13 ± 2 ml/min, with little effect on arterial blood pressure. The time course was similar to that of the tracheal response. This response was greatly attenuated after cervical vagotomy. Blood at 20°C also increased tracheal smooth muscle tension and bronchial flow, whereas 37°C blood had little effect. The results suggest that alteration of airway mechanoreceptor discharge by cooling can initiate reflexes that contribute to airway obstruction.
Carbohydrate and the cytokine response to 2.5 h of running
Authors: Nehlsen-Cannarella S. L. , Fagoaga O. R. , Nieman D. C. , Henson D. A. , Butterworth D. E. , Schmitt R. L. , Bailey E. M. , Warren B. J. , Utter A. , Davis J. M.
Published: December 2017

Nehlsen-Cannarella, S. L., O. R. Fagoaga, D. C. Nieman, D. A. Henson, D. E. Butterworth, R. L. Schmitt, E. M. Bailey, B. J. Warren, A. Utter, and J. M. Davis. Carbohydrate and the cytokine response to 2.5 h of running. J. Appl. Physiol. 82(5): 1662–1667, 1997.—This randomized, double-blind, placebo-controlled study was designed to determine the influence of 6% carbohydrate (C) vs. placebo (P) beverage ingestion on cytokine responses (5 total samples over 9 h) to 2.5 h of high-intensity running (76.7 ± 0.4% maximal O2uptake) by 30 experienced marathon runners. For interleukin-6 (IL-6), a difference in the pattern of change between groups was found, highlighted by a greater increase in P vs. C immediately postrun (753 vs. 421%) and 1.5 h postrun (193 vs. 86%) [ F(4,112) = 3.77, P = 0.006]. For interleukin-1-receptor antagonist (IL-1ra), a difference in the pattern of change between groups was found, highlighted by a greater increase in P vs. C 1.5 h postrun (231 vs. 72%) [ F(2,50) = 6.38, P = 0.003]. No significant interaction effects were seen for bioactive IL-6 or IL-1β. The immediate postrun plasma glucose concentrations correlated negatively with those of plasma cortisol ( r = −0.67, P < 0.001); postrun plasma cortisol ( r = 0.70, P < 0.001) and IL-6 levels ( r = 0.54, P = 0.003) correlated positively with levels of IL-1ra. Taken together, the data indicate that carbohydrate ingestion attenuates cytokine levels in the inflammatory cascade in response to heavy exertion.
Effects of salbutamol on intracellular calcium oscillations in porcine airway smooth muscle
Authors: Prakash Y. S. , Van Der Heijden H. F. M. , Kannan M. S. , Sieck G. C.
Published: December 2017

Prakash, Y. S., H. F. M. van der Heijden, M. S. Kannan, and G. C. Sieck. Effects of salbutamol on intracellular calcium oscillations in porcine airway smooth muscle. J. Appl. Physiol. 82(6): 1836–1843, 1997.—Relaxation of airway smooth muscle (ASM) by β-adrenoceptor agonists involves reduction of intracellular Ca2+concentration ([Ca2+]i). In porcine ASM cells, acetylcholine induces [Ca2+]ioscillations that display frequency modulation by agonist concentration and basal [Ca2+]i. We used real-time confocal microscopy to examine the effect of salbutamol (1 nM to 1 μM), a β2-adrenoceptor agonist, on [Ca2+]ioscillations in freshly dissociated porcine ASM cells. Salbutamol decreased the frequency of [Ca2+]ioscillations in a concentration-dependent fashion, completely inhibiting the oscillations at 1 μM. These effects were mimicked by a cell-permeant analog of adenosine 3′,5′-cyclic monophosphate. The inhibitory effect of salbutamol was partially reversed by BAY K 8644. Salbutamol reduced [Ca2+]ieven when sarcoplasmic reticulum (SR) Ca2+reuptake and Ca2+influx were blocked. Lanthanum blockade of Ca2+efflux attenuated the inhibitory effect of salbutamol on [Ca2+]i. The [Ca2+]iresponse to caffeine was unaffected by salbutamol. On the basis of these results, we conclude that β2-adrenoceptor agonists have little effect on SR Ca2+release in ASM cells but reduce [Ca2+]iby inhibiting Ca2+influx through voltage-gated channels and by enhancing Ca2+efflux.
Augmented sympathetic tone alters muscle metabolism with exercise: lack of evidence for functional sympatholysis
Authors: Shoemaker J. Kevin , Pandey Prasant , Herr Michael D. , Silber David H. , Yang Qing X. , Smith Michael B. , Gray Kristen , Sinoway Lawrence I.
Published: December 2017

Shoemaker, J. Kevin, Prasant Pandey, Michael D. Herr, David H. Silber, Qing X. Yang, Michael B. Smith, Kristen Gray, and Lawrence I. Sinoway. Augmented sympathetic tone alters muscle metabolism with exercise: lack of evidence for functional sympatholysis. J. Appl. Physiol. 82(6): 1932–1938, 1997.—It is unclear whether sympathetic tone opposes dilator influences in exercising skeletal muscle. We examined high levels of sympathetic tone, evoked by lower body negative pressure (LBNP, −60 mmHg) on intramuscular pH and phosphocreatine (PCr) levels (31P-nuclear magnetic resonance spectroscopy) during graded rhythmic handgrip (30 contractions/min; ∼17, 34, 52 and 69% maximal voluntary contraction). Exercise was performed with LBNP and without LBNP (Control). At the end of exercise, LBNP caused lower levels of muscle pH (6.59 ± 0.09) compared with Control (6.78 ± 0.05; P < 0.05). PCr recovery, an index of mitochondrial respiration, was less during the recovery phase of the LBNP trial. Exercise mean arterial pressure was not altered by LBNP. The protocols were repeated with measurements of forearm blood flow velocity and deep venous samples (active forearm) of hemoglobin (Hb) saturation, pH, and lactate. With LBNP, mean blood velocity was reduced at rest, during exercise, and during recovery compared with Control ( P < 0.05). Also, venous Hb saturation and pH levels during exercise and recovery were lower with LBNP and lactate was higher compared with Control ( P < 0.05). We conclude that LBNP enhanced sympathetic tone and reduced oxygen transport. At high workloads, there was a greater reliance on nonoxidative metabolism. In other words, sympatholysis did not occur.
Intravascular oxygen distribution in subcutaneous 9L tumors and radiation sensitivity
Authors: Cerniglia George J. , Wilson David F. , Pawlowski Marek , Vinogradov Sergei , Biaglow John
Published: December 2017

Cerniglia, George J., David F. Wilson, Marek Pawlowski, Sergei Vinogradov, and John Biaglow. Intravascular oxygen distribution in subcutaneous 9L tumors and radiation sensitivity. J. Appl. Physiol. 82(6): 1939–1945, 1997.—Phosphorescence quenching was evaluated as a technique for measuring [Formula: see text] in tumors and for determining the effect of increased[Formula: see text] on sensitivity of the tumors to radiation. Suspensions of cultured 9L cells or small pieces of solid tumors from 9L cells were injected subcutaneously on the hindquarter of rats, and tumors were grown to between 0.2 and 1.0 cm in diameter. Oxygen-dependent quenching of the phosphorescence of intravenously injected Pd-meso-tetra-(4-carboxyphenyl) porphine was used to image the in vivo distribution of [Formula: see text] in the vasculature of small tumors and surrounding tissue. Maps (512 × 480 pixels) of tissue oxygen distribution showed that the[Formula: see text] within 9L tumors was low (2–12 Torr) relative to the surrounding muscle tissue (20–40 Torr). When the rats were given 100% oxygen or carbogen (95% O2-5% CO2) to breathe, the[Formula: see text] in the tumors increased significantly. This increase was variable among tumors and was greater with carbogen compared with 100% oxygen. Based on irradiation and regrowth studies, carbogen breathing increased the sensitivity of the tumors to radiation. This is consistent with the measured increase in[Formula: see text] in the tumor vasculature. It is concluded that phosphorescence quenching can be used for noninvasive determination of the oxygenation of tumors. This method for oxygen measurements has great potential for clinical application in tumor identification and therapy.
Evaluation of estimates of alveolar gas exchange by using a tidally ventilated nonhomogenous lung model
Authors: Busso Thierry , Robbins Peter A.
Published: December 2017

Busso, Thierry, and Peter A. Robbins. Evaluation of estimates of alveolar gas exchange by using a tidally ventilated nonhomogenous lung model. J. Appl. Physiol. 82(6): 1963–1971, 1997.—The purpose of this study was to evaluate algorithms for estimating O2 and CO2 transfer at the pulmonary capillaries by use of a nine-compartment tidally ventilated lung model that incorporated inhomogeneities in ventilation-to-volume and ventilation-to-perfusion ratios. Breath-to-breath O2 and CO2 exchange at the capillary level and at the mouth were simulated by using realistic cyclical breathing patterns to drive the model, derived from 40-min recordings in six resting subjects. The SD of the breath-by-breath gas exchange at the mouth around the value at the pulmonary capillaries was 59.7 ± 25.5% for O2 and 22.3 ± 10.4% for CO2. Algorithms including corrections for changes in alveolar volume and for changes in alveolar gas composition improved the estimates of pulmonary exchange, reducing the SD to 20.8 ± 10.4% for O2 and 15.2 ± 5.8% for CO2. The remaining imprecision of the estimates arose almost entirely from using end-tidal measurements to estimate the breath-to-breath changes in end-expiratory alveolar gas concentration. The results led us to suggest an alternative method that does not use changes in end-tidal partial pressures as explicit estimates of the changes in alveolar gas concentration. The proposed method yielded significant improvements in estimation for the model data of this study.
Endotoxin priming of thromboxane-related vasoconstrictor responses in perfused rabbit lungs
Authors: Steudel Wolfgang , Krämer Hans-Joachim , Degner Daniela , Rosseau Simone , Schütte Hartwig , Walmrath Dieter , Seeger Werner
Published: December 2017

Steudel, Wolfgang, Hans-Joachim Krämer, Daniela Degner, Simone Rosseau, Hartwig Schütte, Dieter Walmrath, and Werner Seeger. Endotoxin priming of thromboxane-related vasoconstrictor responses in perfused rabbit lungs. J. Appl. Physiol. 83(1): 18–24, 1997.—In prior studies of perfused lungs, endotoxin priming markedly enhanced thromboxane (Tx) generation and Tx-mediated vasoconstriction in response to secondarily applied bacterial exotoxins. The present study addressed this aspect in more detail by employing precursor and intermediates of prostanoid synthesis and performing functional testing of vasoreactivity and measurement of product formation. Rabbit lungs were buffer perfused in the absence or presence of 10 ng/ml endotoxin. Repetitive intravascular bolus applications of free arachidonic acid provoked constant pulmonary arterial pressor responses and constant release reactions of TxA2and prostaglandin (PG) I2in nonprimed lungs. Within 60–90 min of endotoxin recirculation, which provoked progressive liberation of tumor necrosis factor-α but did not effect any hemodynamic changes by itself, both pressor responses and prostanoid release markedly increased, and both events were fully blocked by cyclooxygenase (Cyclo) inhibition with acetylsalicylic acid (ASA). The unstable intermediate PGG2provoked moderate pressor responses, again enhanced by preceding endotoxin priming and fully suppressed by ASA. Vasoconstriction also occurred in response to the direct Cyclo product PGH2, again amplified after endotoxin pretreatment, together with markedly enhanced liberation of TxA2and PGI2. In the presence of ASA, the priming-related increase in pressor responses and the prostanoid formation were blocked, but baseline vasoconstrictor responses corresponding to those in nonprimed lungs were maintained. Pressor responses to the stable Tx analog U-46619 were not significantly increased by endotoxin pretreatment, but some generation of TxA2and PGI2was also noted under these conditions. We conclude that endotoxin priming exerts profound effects on the lung vascular prostanoid metabolism, increasing the readiness to react with Tx-mediated vasoconstrictor responses to various stimuli, suggesting that enhanced Cyclo activity is an important underlying event.
Absorption from different intestinal segments during exercise
Authors: Lambert G. P. , Chang R. T. , Xia T. , Summers R. W. , Gisolfi C. V.
Published: December 2017

Lambert, G. P., R. T. Chang, T. Xia, R. W. Summers, and C. V. Gisolfi. Absorption from different intestinal segments during exercise. J. Appl. Physiol. 83(1): 204–212, 1997.—This study evaluated intestinal absorption from the first 75 cm of the proximal small intestine during 85 min of cycle exercise [63.6 ± 0.7% peak O2 consumption (V˙o 2 peak)] while subjects ingested either an isotonic carbohydrate-electrolyte beverage (CHO-E) or a water placebo (WP). The CHO-E beverage contained 117 mM (4%) sucrose, 111 mM (2%) glucose, 18 meq Na+, and 3 meq K+. The two experiments were performed a week apart by seven subjects (6 men and 1 woman; meanV˙o 2 peak = 53.5 ± 6.5 ml ⋅ kg−1 ⋅ min−1). Nasogastric and multilumen tubes were fluoroscopically positioned in the gastric antrum and duodenojejunum, respectively. Subjects ingested 23 ml/kg body weight of the test solution, 20% (383 ± 11 ml) of this volume 5 min before exercise and 10% (191 ± 5 ml) every 10 min thereafter. By using the rate of gastric emptying (18.1 ± 1.1 vs. 19.2 ± 0.7 ml/min for WP and CHO-E, respectively) as the rate of intestinal perfusion, intestinal absorption was determined by segmental perfusion from the duodenum (0–25 cm) and jejunum (25–50 and 50–75 cm). Water flux was different ( P < 0.05) between solutions in the 0- to 25- and 25- to 50-cm segments for WP vs. CHO-E (30.7 ± 2.7 vs. 15.0 ± 2.9 and 3.8 ± 1.1 vs. 11.9 ± 3.3 ml ⋅ cm−1 ⋅ h−1, respectively). Furthermore, water flux differed ( P < 0.05) for WP in a comparison of the 0- to 25- to the 25- to 50-cm segment. Total solute flux (TSF) was not significantly different among segments for a given solution or between solutions for a given segment. There was no difference between trials for percent change in plasma volume. These results indicate that 1) fluid absorption in the proximal small intestine depends on the segment studied and 2) solution composition can significantly effect water absorption rate in different intestinal segments.
Appendicular skeletal muscle mass: effects of age, gender, and ethnicity
Authors: Gallagher Dympna , Visser Marjolein , De Meersman Ronald E. , Sepúlveda Dennis , Baumgartner Richard N. , Pierson Richard N. , Harris Tamara , Heymsfield Steven B.
Published: December 2017

Gallagher, Dympna, Marjolein Visser, Ronald E. De Meersman, Dennis Sepúlveda, Richard N. Baumgartner, Richard N. Pierson, Tamara Harris, and Steven B. Heymsfield. Appendicular skeletal muscle mass: effects of age, gender, and ethnicity. J. Appl. Physiol. 83(1): 229–239, 1997.—This study tested the hypothesis that skeletal muscle mass is reduced in elderly women and men after adjustment first for stature and body weight. The hypothesis was evaluated by estimating appendicular skeletal muscle mass with dual-energy X-ray absorptiometry in a healthy adult cohort. A second purpose was to test the hypothesis that whole body40K counting-derived total body potassium (TBK) is a reliable indirect measure of skeletal muscle mass. The independent effects on both appendicular skeletal muscle and TBK of gender ( n = 148 women and 136 men) and ethnicity ( n = 152 African-Americans and 132 Caucasians) were also explored. Main findings were 1) for both appendicular skeletal muscle mass (total, leg, and arm) and TBK, age was an independent determinant after adjustment first by stepwise multiple regression for stature and weight (multiple regression model r 2 = ∼0.60); absolute decrease with greater age in men was almost double that in women; significantly larger absolute amounts were observed in men and African-Americans after adjustment first for stature, weight, and age; and >80% of within-gender or -ethnic group between-individual component variation was explained by stature, weight, age, gender, and ethnicity differences; and 2) most of between-individual TBK variation could be explained by total appendicular skeletal muscle ( r 2 = 0.865), whereas age, gender, and ethnicity were small but significant additional covariates (total r 2 = 0.903). Our study supports the hypotheses that skeletal muscle is reduced in the elderly and that TBK provides a reasonable indirect assessment of skeletal muscle mass. These findings provide a foundation for investigating skeletal muscle mass in a wide range of health-related conditions.
Modulation of MHC isoforms in functionally overloaded and exercised rat plantaris fibers
Authors: Roy Roland R. , Talmadge Robert J. , Fox Kenneth , Lee Michael , Ishihara Aki , Edgerton V. Reggie
Published: December 2017

Roy, Roland R., Robert J. Talmadge, Kenneth Fox, Michael Lee, Aki Ishihara, and V. Reggie Edgerton. Modulation of MHC isoforms in functionally overloaded and exercised rat plantaris fibers. J. Appl. Physiol. 83(1): 280–290, 1997.—The effects of 1 and 10 wk of functional overload (FO) of the rat plantaris with (FOTr) and without daily endurance treadmill training on its myosin heavy chain (MHC) composition were studied. After 1 and 10 wk of FO, plantaris mass was 22 and 56% greater in FO and 37 and 94% greater, respectively, in FOTr rats compared with age-matched controls. At 1 wk, pure type I and pure type IIa MHC fibers were hypertrophied in FO (39 and 44%) and FOTr (70 and 87%) rats. By 10 wk all fiber types comprising >5% of the fibers sampled showed a hypertrophic response in both FO groups. One week of FO increased the percentage of hybrid (containing both type I and type IIa MHC) fibers and of fibers containing embryonic MHC. By 10 wk, the percentage of pure type I MHC fibers was ∼40% in both FO groups compared with 15% in controls, and the percentage of fibers containing embryonic MHC was similar to that in controls. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed an increase in type I MHC and a decrease in type IIb MHC in both FO groups at 10 wk, whereas little change was observed at 1 wk. These data are consistent with hypertrophy and transformation from faster to slower MHC isoforms in chronically overloaded muscles. The additional overload imposed by daily endurance treadmill training employed in this study (1.6 km/day; 10% incline) results in a larger hypertrophic response but appears to have a minimal effect on the MHC adaptations.
Diaphragm thickening during inspiration
Authors: Cohn David , Benditt Joshua O. , Eveloff Scott , McCool F. Dennis
Published: December 2017

Cohn, David, Joshua O. Benditt, Scott Eveloff, and F. Dennis McCool. Diaphragm thickening during inspiration. J. Appl. Physiol. 83(1): 291–296, 1997.—Ultrasound has been used to measure diaphragm thickness ( T di) in the area where the diaphragm abuts the rib cage (zone of apposition). However, the degree of diaphragm thickening during inspiration reported as obtained by one-dimensional M-mode ultrasound was greater than that predicted by using other radiographic techniques. Because two-dimensional (2-D) ultrasound provides greater anatomic definition of the diaphragm and neighboring structures, we used this technique to reevaluate the relationship between lung volume and T di. We first established the accuracy and reproducibility of 2-D ultrasound by measuring T diwith a 7.5-MHz transducer in 26 cadavers. We found that T di measured by ultrasound correlated significantly with that measured by ruler ( R 2 = 0.89), with the slope of this relationship approximating a line of identity ( y = 0.89 x + 0.04 mm). The relationship between lung volume and T di was then studied in nine subjects by obtaining diaphragm images at the five target lung volumes [25% increments from residual volume (RV) to total lung capacity (TLC)]. Plots of T di vs. lung volume demonstrated that the diaphragm thickened as lung volume increased, with a more rapid rate of thickening at the higher lung volumes [ T di = 1.74 vital capacity (VC)2 + 0.26 VC + 2.7 mm] ( R 2= 0.99; P < 0.001) where lung volume is expressed as a fraction of VC. The mean increase in T di between RV and TLC for the group was 54% (range 42–78%). We conclude that 2-D ultrasound can accurately measure T di and that the average thickening of the diaphragm when a subject is inhaling from RV to TLC using this technique is in the range of what would be predicted from a 35% shortening of the diaphragm.
Spiral nerve cuff electrode for recordings of respiratory output
Authors: Sahin Mesut , Haxhiu Musa A. , Durand Dominique M. , Dreshaj Ismail A.
Published: December 2017

Sahin, Mesut, Musa A. Haxhiu, Dominique M. Durand, and Ismail A. Dreshaj. Spiral nerve cuff electrode for recordings of respiratory output. J. Appl. Physiol.83(1): 317–322, 1997.—The feasibility of using the spiral nerve cuff electrode design for recordings of respiratory output from the hypoglossal (HG) and phrenic nerves is demonstrated in anesthetized, paralyzed, and artificially ventilated cats. Raw neural discharges of the HG nerve were analyzed in terms of signal-to-noise ratios and frequency spectra. The rectified and integrated moving average activity of the HG nerve had a peak value of 1.74 ± 0.21 μV and a baseline value of 0.72 ± 0.11 μV at elevated respiratory drive induced by increases in CO2 or oxygen deprivation when recorded with 10-mm-long cuffs. The frequency content of the HG electroneurogram extended from several hundred hertz to 6 kHz. Spiral nerve cuff recordings without desheathing of the nerve provided large enough signal-to-noise ratios that allowed them to be used as a measure of respiratory output and had much wider frequency bandwidths than the hook electrode preparations. A major advantage of the cuff electrode over the hook electrode was its mechanical stability, which significantly improved the reproducibility of the recordings both in terms of signal amplitudes and frequency contents.
ET-1-induced bronchoconstriction is mediated via ETB receptor in mice
Authors: Nagase Takahide , Aoki Tomoko , Oka Teruaki , Fukuchi Yoshinosuke , Ouchi Yasuyoshi
Published: December 2017

Nagase, Takahide, Tomoko Aoki, Teruaki Oka, Yoshinosuke Fukuchi, and Yasuyoshi Ouchi. ET-1-induced bronchoconstriction is mediated via ETB receptor in mice. J. Appl. Physiol. 83(1): 46–51, 1997.—Endothelin (ET)-1 is one of the most potent agonists of airway smooth muscle and can act via two different ET receptor subtypes, i.e., ETA and ETB. To determine the effects of ET-1 on in vivo pulmonary function and which ET receptors are involved in murine lungs, we investigated 1) the effects of ET and sarafotoxin S6c (S6c), a selective ETB agonist, on pulmonary function and 2) the effects of BQ-123 and BQ-788, specific ETA- and ETB-receptor antagonists, on ET-1-induced bronchoconstriction. ICR mice were anesthetized and mechanically ventilated (frequency = 2.5 Hz, tidal volume = 8 ml/kg, positive end-expiratory pressure = 3 cmH2O). Intravenous ET-1, ET-2, and ET-3 increased lung resistance similarly and equipotently, whereas S6c elicited a greater degree of bronchoconstriction. Mice were then pretreated with saline (Sal), BQ-123 (0.2, 1, and 5 mg/kg), or BQ-788 (0.2, 1, and 5 mg/kg) before administration of ET-1 (10−7 mol/kg iv). No dose of BQ-123 blocked ET-1-induced constriction, whereas pretreatment with each dose of BQ-788 significantly inhibited ET-1-induced responses. There were significant differences in morphometrically assessed airway constriction between Sal and BQ-788 and between BQ-123 and BQ-788, whereas no significant difference was observed between Sal and BQ-123. There were no significant morphometric differences in the airway wall area among the three groups. These observations suggest that the ETB- but not ETA-receptor subtype may mediate the changes in murine pulmonary function in response to ET-1. In addition, the ETB-receptor antagonist reduces ET-1-induced airway narrowing by affecting airway smooth muscle contraction in mice.
Posthemorrhagic antipyresis: what stage of fever genesis is affected?
Authors: Romanovsky Andrej A. , Karman Yelena K.
Published: December 2017

Romanovsky, Andrej A., and Yelena K. Karman.Posthemorrhagic antipyresis: what stage of fever genesis is affected? J. Appl. Physiol. 83(2): 359–365, 1997.—It has been shown that hemorrhage leads to a decreased thermal responsiveness to lipopolysaccharide (LPS). The aim of this study was to clarify what stage of fever genesis [production of endogenous pyrogens such as interleukin-1 (IL-1), increase of the prostaglandin E2(PGE2) concentration in brain tissue, activation of cold-defense effectors] is deficient in posthemorrhagic antipyresis. In adult rabbits, we evaluated the effect of acute hemorrhage (15 ml/kg) on the rectal temperature (Tre) responses to LPS from Salmonella typhi (200 ng/kg iv), ethanol-purified preparation of homologous IL-1 (1 ml from 3.5 × 107 cells, 1.5 ml/kg iv), and PGE2 (1 μg, intracisternal injection). The effect of hemorrhage on Tre was also studied in afebrile rabbits, both at thermoneutrality (23°C) and during ramp cooling (to 7°C). The hemorrhage strongly attenuated the biphasic LPS-induced fever (a Tre rise of 0.4 ± 0.1 instead of 1.2 ± 0.2°C at the time of the second peak), the monophasic Tre response to IL-1 (by ∼0.5°C for over 1–5 h postinjection), and the PGE2-induced hyperthermia (0.4 ± 0.1 vs. 0.9 ± 0.1°C, maxima). In afebrile animals, the hemorrhage neither affected Tre at thermoneutrality nor changed the Tre response to cold exposure. The data suggest that neither insufficiency of cold-defense effectors nor lack of endogenous mediators of fever (IL-1, PGE2) can be the only or even the major cause of posthemorrhagic antipyresis. We speculate that fever genesis is altered at a stage occurring after the intrabrain PGE2 level is increased but before thermoeffectors are activated.
Interaction between airway edema and lung inflation on responsiveness of individual airways in vivo
Authors: Brown Robert H. , Mitzner Wayne , Wagner Elizabeth M.
Published: December 2017

Brown, Robert H., Wayne Mitzner, and Elizabeth M. Wagner.Interaction between airway edema and lung inflation on responsiveness of individual airways in vivo. J. Appl. Physiol. 83(2): 366–370, 1997.—Inflammatory changes and airway wall thickening are suggested to cause increased airway responsiveness in patients with asthma. In five sheep, the dose-response relationships of individual airways were measured at different lung volumes to methacholine (MCh) before and after wall thickening caused by the inflammatory mediator bradykinin via the bronchial artery. At 4 cmH2O transpulmonary pressure (Ptp), 5 μg/ml MCh constricted the airways to a maximum of 18 ± 3%. At 30 cmH2O Ptp, MCh resulted in less constriction (to 31 ± 5%). Bradykinin increased airway wall area at 4 and 30 cmH2O Ptp (159 ± 6 and 152 ± 4%, respectively; P < 0.0001). At 4 cmH2O Ptp, bradykinin decreased airway luminal area (13 ± 2%; P< 0.01), and the dose-response curve was significantly lower ( P = 0.02). At 30 cmH2O, postbradykinin, the maximal airway narrowing was not significantly different (26 ± 5%; P = 0.76). Bradykinin produced substantial airway wall thickening and slight potentiation of the MCh-induced airway constriction at low lung volume. At high lung volume, bradykinin increased wall thickness but had no effect on the MCh-induced airway constriction. We conclude that inflammatory fluid leakage in the airways cannot be a primary cause of airway hyperresponsiveness.
Ventilatory stability to transient CO2 disturbances in hyperoxia and normoxia in awake humans
Authors: Lai Jie , Bruce Eugene N.
Published: December 2017

Lai, Jie, and Eugene N. Bruce. Ventilatory stability to transient CO2 disturbances in hyperoxia and normoxia in awake humans. J. Appl. Physiol. 83(2): 466–476, 1997.—Modarreszadeh and Bruce ( J. Appl. Physiol. 76: 2765–2775, 1994) proposed that continuous random disturbances in arterial [Formula: see text] are more likely to elicit ventilatory oscillation patterns that mimic periodic breathing in normoxia than in hyperoxia. To test this hypothesis experimentally, in nine awake humans we applied pseudorandom binary inspired CO2 fraction stimulation in normoxia and hyperoxia to derive the closed-loop and open-loop ventilatory responses to a brief CO2 disturbance in terms of impulse responses and transfer functions. The closed-loop impulse response has a significantly higher peak value [0.143 ± 0.071 vs. 0.079 ± 0.034 (SD) l ⋅ min−1 ⋅ 0.01 l CO2 −1, P = 0.014] and a significantly shorter 50% response duration (42.7 ± 13.3 vs. 72.3 ± 27.6 s, P = 0.020) in normoxia than in hyperoxia. Therefore, the ventilatory responses to transient CO2 disturbances are less damped (but generally not oscillatory) in normoxia than in hyperoxia. For the closed-loop transfer function, the gain in normoxia increased significantly ( P < 0.0005), while phase delay decreased significantly ( P< 0.0005). The gain increased by 108.5, 186.0, and 240.6%, while phase delay decreased by 26.0, 18.1, and 17.3%, at 0.01, 0.03, and 0.05 Hz, respectively. Changes in the same direction were found for the open-loop system. Generally, an oscillatory ventilatory response to a small transient CO2 disturbance is unlikely during wakefulness. However, changes in parameters that lead to additional increases in chemoreflex loop gain are more likely to initiate oscillations in normoxia than in hyperoxia.
Enhanced ventilatory and exercise performance in athletes with slight expiratory resistive loading
Authors: Fee Lawrence L. , Smith Richard M. , English Michael B.
Published: December 2017

Fee, Lawrence L., Richard M. Smith, and Michael B. English.Enhanced ventilatory and exercise performance in athletes with slight expiratory resistive loading. J. Appl. Physiol. 83(2): 503–510, 1997.—We determined the cardiorespiratory and performance effects of slight (1.5–3.0 cmH2O) expiratory resistive loading (ERL). Twenty-eight highly fit [peak O2 uptake (V˙o 2 peak) = 63.6 ± 1.3 ml ⋅ kg−1 ⋅ min−1] athletes (age = 33.5 ± 1.3 yr) performed pairedV˙o 2 peak cycle ergometer tests (control vs. ERL). End-expiratory lung volume was separately determined in a subset of subjects ( n = 12) at steady-state 75% maximum power output (POmax) and was found to increase (0.67 ± 0.29 liter) with ERL. In theV˙o 2 peaktests, peak expiratory pressure at the mouth, mean inspiratory flow, minute ventilation, and O2 pulse were greater with ERL at every intensity level (i.e., 75, 80, 85, and 90% POmax). Increased minute ventilation was largely due to a trend toward increased tidal volume ( P < 0.05 at 80% POmax). O2 uptake was greater at 90% POmax with ERL. Increased O2 pulse with ERL at comparative workloads suggests that stroke volume was augmented with ERL. Also, with ERL, athletes attained higherV˙o 2 peak (63.0 ± 1.4 vs. 60.1 ± 1.3 ml ⋅ kg−1 ⋅ min−1) and greater POmax (352.0 ± 9.9 vs. 345.7 ± 9.5 W). We conclude that elevated end-expiratory lung volume in response to slight ERL during strenuous exercise served to attenuate both airflow and blood flow limitations, which enhanced exercise capacity.
Capillary recruitment and transit time in the rat lung
Authors: Presson Robert G. , Todoran Thomas M. , De Witt Bracken J. , McMurtry Ivan F. , Wagner Wiltz W.
Published: December 2017

Presson, Robert G., Jr., Thomas M. Todoran, Bracken J. De Witt, Ivan F. McMurtry, and Wiltz W. Wagner, Jr.Capillary recruitment and transit time in the rat lung. J. Appl. Physiol. 83(2): 543–549, 1997.—Increasing pulmonary blood flow and the associated rise in capillary perfusion pressure cause capillary recruitment. The resulting increase in capillary volume limits the decrease in capillary transit time. We hypothesize that small species with relatively high resting metabolic rates are more likely to utilize a larger fraction of gas-exchange reserve at rest. Without reserve, we anticipate that capillary transit time will decrease rapidly as pulmonary blood flow rises. To test this hypothesis, we measured capillary recruitment and transit time in isolated rat lungs. As flow increased, transit time decreased, and capillaries were recruited. The decrease in transit time was limited by an increase in the homogeneity of the transit time distribution and an increased capillary volume due, in part, to recruitment. The recruitable capillaries, however, were nearly completely perfused at flow rates and pressures that were less than basal for the intact animal. This suggests that a limited reserve of recruitable capillaries in the lungs of species with high resting metabolic rates may contribute to their inability to raise O2 consumption manyfold above basal values.
Comparison of effects of sustained isocapnic hypoxia on ventilation in men and women
Authors: Sajkov Dimitar , Neill Alister , Saunders Nicholas A. , McEvoy R. Douglas
Published: December 2017

Sajkov, Dimitar, Alister Neill, Nicholas A. Saunders, and R. Douglas McEvoy. Comparison of the effects of sustained isocapnic hypoxia on ventilation in men and women. J. Appl. Physiol. 83(2): 599–607, 1997.—Sleep-related respiratory disturbances are more common in men than in premenopausal women. This might, in part, be due to different susceptibilities to the respiratory depressant effects of hypoxia. Therefore, we compared ventilation during 10 min of baseline room-air breathing and 20-min sustained isocapnic hypoxia (fractional inspired O2 = 11%, arterial saturation of O2 ≈ 80%) followed by 10 min of breathing 100% O2 in 10 normal men and in 10 women in the follicular phase of the menstrual cycle. Control measurements were made during two transitions from room air (10 min) to 100% O2 (10 min) and averaged. Inspired minute ventilation (V˙i) after 2 min of hypoxia was the same in men and women [131 ± 6.1% baseline for men, 136 ± 7.7% baseline for women; not significant (NS)] and declined to the same level after 20 min (115 ± 5.0% baseline for men, 116 ± 6.6% baseline for women; NS) associated with a similar decline in inspiratory time and tidal volume. Breathing frequency did not change.V˙i decreased transiently during subsequent 100% O2 breathing in both men and women, associated with reduced frequency and duty cycle and increased expiratory time. The fall inV˙i was significantly greater than that observed during control hyperoxia experiments in men but not in women. We conclude that ventilatory responses to sustained isocapnic hypoxia do not differ between awake healthy men and women in the follicular phase of their menstrual cycle. However, after termination of isocapnic hypoxia, men appear to depress their ventilation to a greater degree than women.
Contribution of abdomen and legs to central blood volume expansion in humans during immersion
Authors: Johansen Lars Bo , Jensen Thomas Ulrik Skram , Pump Bettina , Norsk Peter
Published: December 2017

Johansen, Lars Bo, Thomas Ulrik Skram Jensen, Bettina Pump, and Peter Norsk. Contribution of abdomen and legs to central blood volume expansion in humans during immersion. J. Appl. Physiol. 83(3): 695–699, 1997.—The hypothesis was tested that the abdominal area constitutes an important reservoir for central blood volume expansion (CBVE) during water immersion in humans. Six men underwent 1) water immersion for 30 min (WI), 2) water immersion for 30 min with thigh cuff inflation (250 mmHg) during initial 15 min to exclude legs from contributing to CBVE (WI+Occl), and 3) a seated nonimmersed control with 15 min of thigh cuff inflation (Occl). Plasma protein concentration and hematocrit decreased from 68 ± 1 to 64 ± 1 g/l and from 46.7 ± 0.3 to 45.5 ± 0.4% ( P < 0.05), respectively, during WI but were unchanged during WI+Occl. Left atrial diameter increased from 27 ± 2 to 36 ± 1 mm ( P < 0.05) during WI and increased similarly during WI+Occl from 27 ± 2 to 35 ± 1 mm ( P < 0.05). Central venous pressure increased from −3.7 ± 1.0 to 10.4 ± 0.8 mmHg during WI ( P < 0.05) but only increased to 7.0 ± 0.8 mmHg during WI+Occl ( P < 0.05). In conclusion, the dilution of blood induced by WI to the neck is caused by fluid from the legs, whereas the CBVE is caused mainly by blood from the abdomen.
RTN TRH causes prolonged respiratory stimulation
Authors: Cream Carlos L. , Li Aihua , Nattie Eugene E.
Published: December 2017

Cream, Carlos L., Aihua Li, and Eugene E. Nattie. RTN TRH causes prolonged respiratory stimulation. J. Appl. Physiol. 83(3): 792–799, 1997.—We injected thyrotropin-releasing hormone (TRH; 10 nl; 0.25, 0.5, 1.0, or 10 mM), its inactive free acid form (TRHOH; 1 mM), or a metabolite with low TRH-receptor binding affinity, histidine-proline diketopiperazine (cHP; 1 mM), into the retrotrapezoid nucleus of anesthetized rats. Injection location was verified by anatomic analysis. Lower doses (0.25–0.5 mM) significantly increased both the product of integrated phrenic amplitude and frequency ([Formula: see text]Phr ⋅ f) and f for 20–30 min compared with artificial cerebrospinal fluid control injections. Higher doses (1.0–10 mM) produced greater and long-lasting stimulation of [Formula: see text]Phr ⋅ f,[Formula: see text]Phr, and f and of blood pressure. This stimulation reached values 150% of baseline and durations of 270 min after a single injection. TRHOH (1 mM ) or cHP (1 mM) had no effect on[Formula: see text]Phr but increased f, as did 1 mM TRH. We conclude that TRH has a very powerful stimulatory effect in the retrotrapezoid nucleus region on [Formula: see text]Phr ⋅ f, with the [Formula: see text]Phr response seemingly specific for TRH receptors. Similar responses of f to TRHOH and cHP suggest it may be nonspecific.
Contraction-induced injury to the extensor digitorum longus muscles of rats: the role of vitamin E
Authors: Van Der Meulen Jack H. , McArdle Anne , Jackson Malcolm J. , Faulkner John A.
Published: December 2017

Van der Meulen, Jack H., Anne McArdle, Malcolm J. Jackson, and John A. Faulkner. Contraction-induced injury to the extensor digitorum longus muscles of rats: the role of vitamin E. J. Appl. Physiol. 83(3): 817–823, 1997.—Three days after a protocol of 225 pliometric (lengthening) contractions was administered to in situ extensor digitorum longus muscles of rats, the force deficit was 64 ± 7% and the percentage of damaged muscle fibers was 38 ± 5% of the control values. We then tested the hypothesis that at 3 h and 3 days after the protocol an elevation in the muscle vitamin E content would decrease the force deficit, the percentage of damaged muscle fibers, and the serum activities of creatine kinase and pyruvate kinase. The 5–8 days of intravenous injections of α-tocopherol increased muscle vitamin E content threefold compared with vehicle (ethanol)-treated rats. Despite the difference in vitamin E content, the force deficit and number of damaged fibers were not different. After the contraction protocol, the serum creatine kinase and pyruvate kinase activities of the vehicle-treated rats increased fourfold at 3 h and twofold at 3 days, whereas the vitamin E-treated rats showed no change. We conclude that vitamin E treatment did not ameliorate either the induction of the injury or the more severe secondary injury at 3 days. Despite the absence of evidence for an antioxidant function, the lack of any increase in serum enzyme activities for vitamin E-treated rats at 3 h and 3 days supported a role for vitamin E in the prevention of enzyme loss after muscle damage.
Ragweed sensitization alters pulmonary vascular responses to bronchoprovocation in beagle dogs
Authors: Theodorou Andreas , Weger Natalie , Kunke Kathleen , Rhee Kyoo , Bice David , Muggenberg Bruce , Lemen Richard
Published: December 2017

Theodorou, Andreas, Natalie Weger, Kathleen Kunke, Kyoo Rhee, David Bice, Bruce Muggenberg, and Richard Lemen. Ragweed sensitization alters pulmonary vascular responses to bronchoprovocation in beagle dogs. J. Appl. Physiol.83(3): 912–917, 1997.—In ragweed (RW)-sensitized beagle dogs, we tested the hypothesis that reactivity of the pulmonary vasculature was enhanced with aerosolized histamine (Hist) and RW. Seven dogs were neonatally sensitized with repeated intraperitoneal RW injections, and 12 dogs were controls (Con). The dogs were anesthetized with intravenous chloralose, mechanically ventilated, and instrumented with femoral arterial and pulmonary artery catheters. Specific lung compliance (Clsp), specific lung conductance (Gsp), systemic vascular resistance index, and pulmonary vascular resistance index (PVRI) were measured before and after bronchoprovocation with Hist and RW. After Hist inhalation (5 breaths of 30 mg/ml), both Con and RW dogs had significant ( P < 0.05) decreases in Clsp(−51 ± 4 and −53 ± 5%, respectively) and Gsp(−65 ± 5 and −69 ± 3%, respectively), but only RW-sensitized dogs had a significant increase in PVRI (38 ± 10%). After RW inhalation (60 breaths of 0.8 mg/ml), only RW-sensitized dogs had significant increases (62 ± 20%) in PVRI and decreases in Gsp(−77 ± 4%) and Clsp(−65 ± 7%). We conclude that, compared with Con, RW-sensitized beagle dogs have increased pulmonary vasoconstrictive responses with Hist or RW inhalation.
Alterations in growth and body composition during puberty. I. Comparing multicompartment body composition models
Authors: Roemmich James N. , Clark Pamela A. , Weltman Arthur , Rogol Alan D.
Published: December 2017

Roemmich, James N., Pamela A. Clark, Arthur Weltman, and Alan D. Rogol. Alterations in growth and body composition during puberty. I. Comparing multicompartment body composition models. J. Appl. Physiol. 83(3): 927–935, 1997.—A four-compartment (4C) model of body composition was used as a criterion to determine the accuracy of three-compartment (3C) and two-compartment (2C) models to estimate percent body fat (%BF) in prepubertal and pubertal boys (genital I & II, n = 17; genital III & IV, n = 7) and girls (breast I & II, n = 8; breast III & IV, n = 15). The 3C water-density (3C-H2O) and 3C mineral-density models, dual-energy X-ray absorptiometry, the Lohman age-adjusted equations, the Slaughter et al. skinfold equations, and the Houtkooper et al. and Boileau bioelectrical impedance equations were evaluated. Agreement with the 4C model increased with the number of compartments (i.e., body water, bone mineral) measured. Except for the 3C-H2O model, the limits of agreement were large and did not perform well for individuals. The mean %BF by dual-energy X-ray absorptiometry (23.6%) was greater than that of the criterion 4C method (21.7%). For the field methods, the Slaughter et al. skinfold equations performed better than did the Houtkooper et al. and Boileau bioimpedance equations. The hydration of the fat-free mass decreased (genital I & II = 75.7%, genital III & IV = 74.8%, breast I & II = 75.5%, breast III & IV = 74.4%) and the mineral content increased (genital I & II = 4.9%, genital III & IV = 5.0%, breast I & II = 5.1%, breast III & IV = 5.7%) with maturation. The density of the fat-free mass also increased (genital I & II = 1.084 g/ml, genital III & IV = 1.087 g/ml, breast I & II = 1.086 g/ml, breast III & IV = 1.091 g/ml) with maturation. All of the models reduced the %BF overprediction of the Siri 2C model, but only the 4C and 3C-H2O models should be used as criterion methods for body composition validation in children and adolescents.