bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid regulatory hormone response to exercise after coca-induced body fluid shifts
Authors: Favier R. , Caceres E. , Sempore B. , Cottet-Emard J. M. , Gauquelin G. , Gharib C. , Spielvogel H.
Published: December 2017

Favier, R., E. Caceres, B. Sempore, J. M. Cottet-Emard, G. Gauquelin, C. Gharib, and H. Spielvogel. Fluid regulatory hormone response to exercise after coca-induced body fluid shifts. J. Appl. Physiol. 83(2): 376–382, 1997.—To determine the effect of coca chewing on heart rate (HR), mean arterial blood pressure (MAP), and plasma volume and their relationship with the hormones regulating cardiovascular and body fluid homeostasis, 16 male volunteers were examined at rest and during 1 h of cycle exercise at ∼75% of their peak oxygen uptake in two trials separated by 1 mo. One trial was performed after the subjects chewed a sugar-free chewing gum (Coca− trial), whereas the other was done after the subjects chewed 15 g of coca leaves (Coca+), with the order of the Coca− and Coca+ trials being randomized. Blood samples were taken at rest, before (R1) and after 1-h chewing (R2), and during the 5th, 15th, 30th, and 60th min of exercise. They were analyzed for hematocrit, hemoglobin concentration, red blood cell count, plasma proteins, and for the fluid regulatory hormones, including plasma catecholamines [norepinephrine (NE) and epinephrine], renin, arginine vasopressin, and the atrial natriuretic peptide (ANP). During the control trial (Coca−), from R1 to R2, there was no significant change in hematologic, hormonal, and cardiovascular status except for a small increase in plasma NE. In contrast, it can be calculated that coca chewing at rest induced a significant hemoconcentration (−3.8 ± 1.3% in blood and −7.0 ± 0.7% in plasma volume), increased NE and MAP, and reduced plasma ANP. Chewing coca before exercise reduced the body fluid shifts but enhanced HR response during exercise. These effects were not accompanied by changes in NE, epinephrine, renin, and arginine vasopressin plasma levels. In contrast, plasma ANP response to exercise was lower during the Coca+ trial, suggesting that central cardiac filling was reduced by coca use. It is likely that the reduction in body fluid volumes is a major contributing factor to the higher HR at any given time of exercise after coca chewing.
Comparative hemodynamic effects of periodic obstructive and simulated central apneas in sedated pigs
Authors: Chen Ling , Scharf Steven M.
Published: December 2017

Chen, Ling, and Steven M. Scharf. Comparative hemodynamic effects of periodic obstructive and simulated central apneas in sedated pigs. J. Appl. Physiol. 83(2): 485–494, 1997.—It has been speculated that because of increased left ventricular (LV) afterload, decreased intrathoracic pressure (ITP) is responsible for decreased cardiac output (CO) in obstructive sleep apnea. If this were true, then obstructive apnea (OA) should have a greater effect on CO than would central apnea (CA). To assess the importance of decreased ITP during OA, we studied seven preinstrumented sedated pigs with OA and simulated CA that were matched for blood gases and apnea periodicities (with 15- or 30-s apnea duration). Compared with OA, CA with 30-s apnea duration produced comparable decreases in heart rate (from baseline to end apnea: OA, 106.6 ± 4.8 to 93.4 ± 4.4 beats/min, P < 0.01; and CA, 111.1 ± 6.2 to 94.0 ± 5.2 beats/min, P < 0.01) and comparable increases in LV end-diastolic pressure and LV end-diastolic myocardial segment length but greater increases in mean arterial pressure (97.1 ± 3.7 to 107.7 ± 4.3 Torr, P < 0.05; and 97.3 ± 4.8 to 119.3 ± 7.4 Torr, P < 0.01) and systemic vascular resistance (2,577 ± 224 to 3,346 ± 400 dyn ⋅ s ⋅ cm−5, P < 0.01; and 2,738 ± 294 to 5,111 ± 1,181 dyn ⋅ s ⋅ cm−5, P < 0.01) and greater decreases in CO (3.18 ± 0.31 to 2.74 ± 0.26 l/min, P < 0.05; and 3.07 ± 0.38 to 2.30 ± 0.36 l/min, P < 0.01) and stroke volume (32.2 ± 2.9 to 25.9 ± 2.4 ml, P < 0.05; and 31.5 ± 1.9 to 19.8 ± 3.1 ml, P < 0.01). Only CA increased LV end-systolic myocardial segment length. Similar findings were observed with 15-s apnea duration. We conclude that CA produced greater depression of CO and greater changes of afterload-related LV dysfunction than did OA. Therefore, decreased ITP was not the dominant factor determining LV function with apneas.
Effect of 2,4-dinitrophenol on the hypometabolic response to hypoxia of conscious adult rats
Authors: Saiki Chikako , Mortola Jacopo P.
Published: December 2017

Saiki, Chikako, and Jacopo P. Mortola. Effect of 2,4-dinitrophenol on the hypometabolic response to hypoxia of conscious adult rats. J. Appl. Physiol. 83(2): 537–542, 1997.—During acute hypoxia, a hypometabolic response is commonly observed in many newborn and adult mammalian species. We hypothesized that, if hypoxic hypometabolism were entirely a regulated response with no limitation in O2availability, pharmacological uncoupling of the oxidative phosphorylation should raise O2consumption (V˙o 2) by similar amounts in hypoxia and normoxia. Metabolic, ventilatory, and cardiovascular measurements were collected from conscious rats in air and in hypoxia, both before and after intravenous injection of the mitochondrial uncoupler 2,4-dinitrophenol (DNP). In hypoxia (10% O2 breathing, 60% arterial O2 saturation),V˙o 2, as measured by an open-flow technique, was less than in normoxia (∼80%). Successive DNP injections (6 mg/kg, 4 times) progressively increasedV˙o 2 in both normoxia and hypoxia by similar amounts. Body temperature slightly increased in normoxia, whereas it did not change in hypoxia. The DNP-stimulatedV˙o 2 during hypoxia could even exceed the control normoxic value. A single DNP injection (17 mg/kg iv) had a similar metabolic effect; it also resulted in hypotension and a drop in systemic vascular resistance. We conclude that pharmacological stimulation ofV˙o 2 counteracts theV˙o 2 drop determined by hypoxia and stimulates V˙o 2not dissimilarly from normoxia. Hypoxic hypometabolism is likely to reflect a regulated process of depression of thermogenesis, with no limitation in cellular O2availability.
Aerosolized manganese SOD decreases hyperoxic pulmonary injury in primates. II. Morphometric analysis
Authors: Welty-Wolf Karen E. , Simonson Steven G. , Huang Yuh-Chin T. , Kantrow Stephen P. , Carraway Martha S. , Chang Ling-Yi , Crapo James D. , Piantadosi Claude A.
Published: December 2017

Welty-Wolf, Karen E., Steven G. Simonson, Yuh-Chin T. Huang, Stephen P. Kantrow, Martha S. Carraway, Ling-Yi Chang, James D. Crapo, and Claude A. Piantadosi. Aerosolized manganese SOD decreases hyperoxic pulmonary injury in primates. II. Morphometric analysis. J. Appl. Physiol. 83(2): 559–568, 1997.—Hyperoxia damages lung parenchyma via increased cellular production of reactive oxygen species that exceeds antioxidant defenses. We hypothesized that aerosolized human recombinant manganese superoxide dismutase (rhMnSOD) would augment extracellular antioxidant defenses and attenuate epithelial injury in the lung during hyperoxia in primates. Twenty-four adult male baboons were anesthetized and mechanically ventilated with 100% oxygen for 96 h. The baboons were divided equally into four groups. Oxygen alone and oxygen plus rhMnSOD given at 3 mg ⋅ kg−1⋅ day−1were compared to assess efficacy of the drug. Subsequently, aerosolized rhMnSOD was given at 1 or 10 mg ⋅ kg−1⋅ day−1to study dose effects and toxicity. Quantitative morphometry showed protection of alveolar epithelium from hyperoxia by 3 mg ⋅ kg−1⋅ day−1rhMnSOD ( P < 0.05). In addition, interstitial fibroblast volumes were increased in the treatment group ( P = 0.06). This effect appeared greater at the two higher doses of the rhMnSOD. The aerosolized drug was localized to the surface of airways and air spaces and macrophages by immunolabeling studies, suggesting efficacy via physicochemical properties that localize it to cell surfaces or by effects on alveolar macrophage function.
Exercise performance of Tibetan and Han adolescents at altitudes of 3,417 and 4,300 m
Authors: Chen Qiu-Hong , Ge Ri-Li , Wang Xiao-Zhen , Chen Hui-Xin , Wu Tian-Yi , Kobayashi Toshio , Yoshimura Kazuhiko
Published: December 2017

Chen, Qiu-Hong, Ri-Li Ge, Xiao-Zhen Wang, Hui-Xin Chen, Tian-Yi Wu, Toshio Kobayashi, and Kazuhiko Yoshimura. Exercise performance of Tibetan and Han adolescents at altitudes of 3,417 and 4,300 m. J. Appl. Physiol. 83(2): 661–667, 1997.—The difference was studied between O2 transport in lifelong Tibetan adolescents and in newcomer Han adolescents acclimatized to high altitude. We measured minute ventilation, maximal O2 uptake, maximal cardiac output, and arterial O2 saturation during maximal exercise, using the incremental exercise technique, at altitudes of 3,417 and 4,300 m. The groups were well matched for age, height, and nutritional status. The Tibetans had been living at the altitudes for a longer period than the Hans (14.5 ± 0.2 vs. 7.8 ± 0.8 yr at 3,417 m, P < 0.01; and 14.7 ± 0.3 vs. 5.3 ± 0.7 yr at 4,300 m, P < 0.01, respectively). At rest, Tibetans had significantly greater vital capacity and maximal voluntary ventilation than the Hans at both altitudes. At maximal exercise, Tibetans compared with Hans had higher maximal O2 uptake (42.2 ± 1.7 vs. 36.7 ± 1.2 ml ⋅ min−1 ⋅ kg−1at 3,417 m, P < 0.01; and 36.8 ± 1.9 vs. 30.0 ± 1.4 ml ⋅ min−1 ⋅ kg−1at 4,300 m, P < 0.01, respectively) and greater maximal cardiac output (12.8 ± 0.3 vs. 11.4 ± 0.2 l/min at 3,417 m, P < 0.01; 11.5 ± 0.5 vs. 10.0 ± 0.5 l/min at 4,300 m, P < 0.05, respectively). Although the differences in arterial O2saturation between Tibetans and Hans were not significant at rest and during mild exercise, the differences became greater with increases in exercise workload at both altitudes. We concluded that exposure to high altitude from birth to adolescence resulted in an efficient O2 transport and a greater aerobic exercise performance that may reflect a successful adaptation to life at high altitude.
Insulin activation of phosphatidylinositol 3-kinase in human skeletal muscle in vivo
Authors: Hickey Matthew S. , Tanner Charles J. , O’Neill D. Sean , Morgan Lydia J. , Dohm G. Lynis , Houmard Joseph A.
Published: December 2017

Hickey, Matthew S., Charles J. Tanner, D. Sean O’Neill, Lydia J. Morgan, G. Lynis Dohm, and Joseph A. Houmard. Insulin activation of phosphatidylinositol 3-kinase in human skeletal muscle in vivo. J. Appl. Physiol. 83(3): 718–722, 1997.—The purpose of this investigation was to determine whether insulin-stimulated phosphatidylinositol 3-kinase (PI3-kinase) activity is detectable in needle biopsies of human skeletal muscle. Sixteen healthy nonobese males matched for age, percent fat, fasting insulin, and fasting glucose participated in one of two experimental protocols. During an intravenous glucose tolerance test (IVGTT) protocol, insulin-stimulated PI3-kinase activity was determined from percutaneous needle biopsies at 2, 5, and 15 min post-insulin administration (0.025 U/kg). In the second group, a 2-h, 100 mU ⋅ m−2⋅ min−1euglycemic hyperinsulinemic clamp was performed, and biopsies were obtained at 15, 60, and 120 min after insulin infusion was begun. Insulin stimulated PI3-kinase activity by 1.6 ± 0.2-, 2.2 ± 0.3-, and 2.2 ± 0.4-fold at 2, 5, and 15 min, respectively, during the IVGTT. During the clamp protocol, PI3-kinase was elevated by 5.3 ± 1.3-, 8.0 ± 2.6-, and 2.7 ± 1.4-fold above basal at 15, 60, and 120 min, respectively. Insulin-stimulated PI3-kinase activity at 15 min post-insulin administration was significantly greater during the clamp protocol vs. the IVGTT ( P < 0.05). These observations suggest that insulin-stimulated PI3-kinase activity is detectable in needle biopsies of human skeletal muscle, and furthermore, that the euglycemic, hyperinsulinemic clamp protocol may be a useful tool to assess insulin signaling in vivo.
Pharmacological modulation of the mechanical response of airway smooth muscle to length oscillation
Authors: Shen X. , Wu M. F. , Tepper R. S. , Gunst S. J.
Published: December 2017

Shen, X., M. F. Wu, R. S. Tepper, and S. J. Gunst. Pharmacological modulation of the mechanical response of airway smooth muscle to length oscillation. J. Appl. Physiol. 83(3): 739–745, 1997.—Stretch and retraction of the airways caused by changes in lung volume may play an important role in regulating airway reactivity. We studied the effects of different pharmacological stimuli on airway smooth muscle to determine whether the muscle behavior during length oscillation can be modulated pharmacologically and to evaluate the role of different activation mechanisms in determining its behavior during the oscillation. Active force decreased below the static isometric force during the shortening phase of length oscillation, resulting in an overall depression of force during the length oscillation cycle. This pattern of response was unaffected by the contractile stimulus or level of activation, suggesting that it was caused by a mechanism that is independent of the level of activation of cross bridges. The normalized area of the length-force hysteresis loop (hysteresivity) differed depending on the stimulus used for contraction. Effects of different stimuli on hysteresivity were not correlated with their effects on isotonic shortening velocity or isometric force, suggesting that the pharmacological modulation of the behavior of airway smooth muscle during length oscillation at these amplitudes cannot be accounted for by the effects on the cross-bridge cycling rate.
Pulmonary tissue volume, cardiac output, and diffusing capacity in sustained microgravity
Authors: Verbanck Sylvia , Larsson Hans , Linnarsson Dag , Prisk G. Kim , West John B. , Paiva Manuel
Published: December 2017

Verbanck, Sylvia, Hans Larsson, Dag Linnarsson, G. Kim Prisk, John B. West, and Manuel Paiva. Pulmonary tissue volume, cardiac output and diffusing capacity in sustained microgravity. J. Appl. Physiol. 83(3): 810–816, 1997.—In microgravity (μG) humans have marked changes in body fluids, with a combination of an overall fluid loss and a redistribution of fluids in the cranial direction. We investigated whether interstitial pulmonary edema develops as a result of a headward fluid shift or whether pulmonary tissue fluid volume is reduced as a result of the overall loss of body fluid. We measured pulmonary tissue volume (Vti), capillary blood flow, and diffusing capacity in four subjects before, during, and after 10 days of exposure to μG during spaceflight. Measurements were made by rebreathing a gas mixture containing small amounts of acetylene, carbon monoxide, and argon. Measurements made early in flight in two subjects showed no change in Vti despite large increases in stroke volume (40%) and diffusing capacity (13%) consistent with increased pulmonary capillary blood volume. Late in-flight measurements in four subjects showed a 25% reduction in Vti compared with preflight controls ( P < 0.001). There was a concomittant reduction in stroke volume, to the extent that it was no longer significantly different from preflight control. Diffusing capacity remained elevated (11%; P< 0.05) late in flight. These findings suggest that, despite increased pulmonary perfusion and pulmonary capillary blood volume, interstitial pulmonary edema does not result from exposure to μG.
Modulation of NK cell cytolytic activity by macrophages in chronically exercise-stressed mice
Authors: Blank Sally E. , Jones T. Bucky , Lee Eric G. , Brahler C. Jayne , Gallucci Randle M. , Fox Marne L. , Meadows Gary G.
Published: December 2017

Blank, Sally E., T. Bucky Jones, Eric G. Lee, C. Jayne Brahler, Randle M. Gallucci, Marne L. Fox, and Gary G. Meadows.Modulation of NK cell cytolytic activity by macrophages in chronically exercise-stressed mice. J. Appl. Physiol. 83(3): 845–850, 1997.—This study was designed to investigate the effects of moderate-intensity endurance training on basal natural killer (NK) cell cytolytic activity in murine splenocytes that were enriched for 1) NK1.1+cells or 2) macrophages and NK1.1+cells. Mice were assigned to sedentary (Sed), treadmill control (TM), or treadmill-trained (Trn) groups. Splenocyte number, the percentages of NK1.1+, large granular lymphocytes (NK1.1+, LGL-1+), and other subpopulations did not change in Trn mice. Approximately 70% of cells enriched for NK1.1+expressed this surface antigen. Lytic units (LU) expressed per LGL-1+cell were significantly lower in Trn [83.9 ± 3.2 (SE)] compared with Sed (109.5 ± 7.5) and TM (101.3 ± 6.4) groups. When macrophages remained in the in vitro assay, LU per LGL-1+cell did not differ across groups. The results indicate that highly enriched NK1.1+cells from Trn mice had lower NK cell activity compared with Sed mice. No differences in NK cell activity were observed when cells were enriched for NK1.1+cells and macrophages. These findings support the hypothesis that macrophage modulation of NK cells may be one mechanism contributing to augmented basal NK cell activity in endurance-trained individuals.
Rate and composition of sweat fluid losses are unaltered by hypohydration during prolonged exercise in horses
Authors: Kingston Janene K. , Geor Raymond J. , McCutcheon Laura Jill
Published: December 2017

Kingston, Janene K., Raymond J. Geor, and Laura Jill McCutcheon. Rate and composition of sweat fluid losses are unaltered by hypohydration during prolonged exercise in horses. J. Appl. Physiol. 83(4): 1133–1143, 1997.— Rate and ionic composition of sweat fluid losses and partitioning of evaporative heat loss into respiratory and cutaneous components were determined in six horses during three 15-km phases of exercise at ∼40% of maximal O2uptake. Pattern of change in sweat rate (SR) and composition was similar during each phase. SR increased rapidly for the first 20 min of exercise but remained at ∼24–28 ml ⋅ m−2⋅ min−1during the remainder of each phase. Similarly, the concentrations of Na and Cl in sweat increased until 30 min of exercise but were unchanged thereafter. Sweat osmolality and concentrations of Na and Cl were positively correlated with SR. Sweat K concentration decreased during exercise but was not correlated with SR. Fluid losses were 33.8 ± 1.5 liters, resulting in decreases of ∼21% in plasma volume and ∼11% in total body water. The ∼6% hypohydration was not associated with an alteration in SR, sweat composition, or heat storage. Respiratory and cutaneous evaporative heat loss represented ∼23 and 70%, respectively, of the total heat dissipated, and the partitioning of heat loss was similar in each exercise phase. We conclude that SR and the relative proportions of respiratory and cutaneous evaporative heat loss are unchanged in horses during prolonged low-intensity exercise despite moderate hypohydration.
Myogenic regulatory factors during regeneration of skeletal muscle in young, adult, and old rats
Authors: Marsh Daniel R. , Criswell David S. , Carson James A. , Booth Frank W.
Published: December 2017

Marsh, Daniel R., David S. Criswell, James A. Carson, and Frank W. Booth. Myogenic regulatory factors during regeneration of skeletal muscle in young, adult, and old rats. J. Appl. Physiol. 83(4): 1270–1275, 1997.—Myogenic factor mRNA expression was examined during muscle regeneration after bupivacaine injection in Fischer 344/Brown Norway F1 rats aged 3, 18, and 31 mo of age (young, adult, and old, respectively). Mass of the tibialis anterior muscle in the young rats had recovered to control values by 21 days postbupivacaine injection but in adult and old rats remained 40% less than that of contralateral controls at 21 and 28 days of recovery. During muscle regeneration, myogenin mRNA was significantly increased in muscles of young, adult, and old rats 5 days after bupivacaine injection. Subsequently, myogenin mRNA levels in young rat muscle decreased to postinjection control values by day 21 but did not return to control values in 28-day regenerating muscles of adult and old rats. The expression of MyoD mRNA was also increased in muscles at day 5 of regeneration in young, adult, and old rats, decreased to control levels by day 14 in young and adult rats, and remained elevated in the old rats for 28 days. In summary, either a diminished ability to downregulate myogenin and MyoD mRNAs in regenerating muscle occurs in old rat muscles, or the continuing myogenic effort includes elevated expression of these mRNAs.
Effects of endurance training on the cardiovascular system and water compartments in elderly subjects
Authors: Pickering Gisèle P. , Fellmann Nicole , Morio Béatrice , Ritz Patrick , Amonchot Aimé , Vermorel Michel , Coudert Jean
Published: December 2017

Pickering, Gisèle P., Nicole Fellmann, Béatrice Morio, Patrick Ritz, Aimé Amonchot, Michel Vermorel, and Jean Coudert. Effects of endurance training on the cardiovascular system and water compartments in elderly subjects. J. Appl. Physiol. 83(4): 1300–1306, 1997.—The effects of endurance training on the water compartments and the cardiovascular system were determined in 10 elderly subjects [age 62 ± 2 yr, pretraining maximal oxygen consumption (V˙o 2 max)/kg = 25 ± 2 ml ⋅ min−1 ⋅ kg−1body wt]. They trained on a cycloergometer 3 times/wk for 16 wk (50–80%V˙o 2 max, then 80–85%V˙o 2 max). They were checked at 8 wk, 16 wk, and 4 mo after detraining. Training improvedV˙o 2 max (+16%) and induced plasma volume expansion (+11%). No change in total body water, extracellular fluid, interstitial and intracellular fluid volumes, fat-free mass, and body weight was detected in this small sample with training. Body fat mass decreased (−2.1 ± 2.2 kg). Echocardiography at rest showed increased fractional shortening and ejection fraction and decreased left ventricular end-systolic dimension ( P < 0.05). Blood volume expansion correlates with cardiac contractility and has an impact on cardiac function. These improvements are precarious, however, and are completely lost after 4 mo of detraining, when elderly subjects lose the constraints and the social stimulation of the imposed protocol.
Dynamic properties of lung parenchyma: mechanical contributions of fiber network and interstitial cells
Authors: Yuan Huichin , Ingenito Edward P. , Suki Béla
Published: December 2017

Yuan, Huichin, Edward P. Ingenito, and Béla Suki.Dynamic properties of lung parenchyma: mechanical contributions of fiber network and interstitial cells. J. Appl. Physiol. 83(5): 1420–1431, 1997.—We investigated the contributions of the connective tissue fiber network and interstitial cells to parenchymal mechanics in a surfactant-free system. In eight strips of uniform dimension from guinea pig lung, we assessed the storage (G′) and loss (G”) moduli by using pseudorandom length oscillations containing a specially designed set of seven frequencies from 0.07 to 2.4 Hz at baseline, during methacholine (MCh) challenge, and after death of the interstitial cells. Measurements were made at mean forces of 0.5 and 1 g and strain amplitudes of 5, 10, and 15% and were repeated 12 h later in the same, but nonviable samples. The results were interpreted using a linear viscoelastic model incorporating both tissue damping (G) and stiffness (H). The G′ and G” increased linearly with the logarithm of frequency, and both G and H showed negative strain amplitude and positive mean force dependence. After MCh challenge, the G′ and G” spectra were elevated uniformly, and G and H increased by <15%. Tissue stiffness, strain amplitude, and mean force dependence were virtually identical in the viable and nonviable samples. The G and hence energy dissipation were ∼10% smaller in the nonviable samples due to absence of actin-myosin cross-bridge cycling. We conclude that the connective tissue network may also dominate parenchymal mechanics in the intact lung, which can be influenced by the tone or contraction of interstitial cells.
Role of circulating blood components and thromboxane in anaphylactic vasoconstriction in isolated canine lungs
Authors: Miyahara Takashige , Shibamoto Toshishige , Wang Hong-Gang , Koyama Shozo
Published: December 2017

Miyahara, Takashige, Toshishige Shibamoto, Hong-Gang Wang, and Shozo Koyama. Role of circulating blood components and thromboxane in anaphylactic vasoconstriction in isolated canine lungs. J. Appl. Physiol. 83(5): 1508–1516, 1997.—We determined the roles of circulating blood components and chemical mediators in anaphylactic vasoconstriction and microvascular permeability during Ascaris suum antigen-induced anaphylaxis in isolated canine lungs. Either the right or left lower lobe served as the control lung, which was perfused with autologous blood, and the contralateral lobe from the same dog was examined for the effect of albumin Krebs-Henseleit solution (Krebs) or of blockers of various vasoconstrictors with blood perfusion. Pulmonary vasoconstriction occurred after injection of the antigen (15 mg) in both the blood- and Krebs-perfused lungs. However, the percent change of peak pulmonary vascular resistance in the Krebs-perfused lungs tended to be greater than that in the blood-perfused lungs (689.9 ± 289.3 and 389.3 ± 171.9%, respectively). This increased peak pulmonary vascular resistance was attenuated similarly by pretreatment with indomethacin (1.1 × 10−4M; cyclooxygenase inhibitor), AA-2414 (10−5M; thromboxane-receptor antagonist), or a combination of TCV-309 (10−5M; platelet-activating factor-receptor antagonist), diphenhydramine (1.7 × 10−4M, histamine H1-receptor antagonist), and indomethacin but not by pretreatment with TCV-309 or diphenhydramine alone. The filtration coefficient, an index of vascular permeability, did not change significantly at 15 or 60 min after the antigen in all groups. These findings suggest that anaphylactic vasoconstriction in the isolated canine lung is independent of circulating blood components. Thromboxane is the major mediator for the anaphylactic vasoconstriction. Anaphylaxis does not increase pulmonary vascular permeability in isolated canine lungs.
Effects of a training program on resting plasma 2-hydroxycatecholestrogen levels in eumenorrheic women
Authors: De Crée Carl , Ball Peter , Seidlitz Bärbel , Van Kranenburg Gerrit , Geurten Peter , Keizer Hans A.
Published: December 2017

De Crée, Carl, Peter Ball, Bärbel Seidlitz, Gerrit Van Kranenburg, Peter Geurten, and Hans A. Keizer.Effects of a training program on resting plasma 2-hydroxycatecholestrogen levels in eumenorrheic women. J. Appl. Physiol. 83(5): 1551–1556, 1997.—Catecholestrogens (CE) represent a major metabolic pathway in estrogen metabolism. Previous information on CE and training is limited to two cross-sectional studies that did not involve standardized training. Our purpose, by means of a prospective design, was to evaluate the effects of a brief, exhaustive training program on resting plasma concentrations of 2-hydroxy CE. The experimental design spanned two menstrual cycles: a control cycle and a training cycle. The subjects were nine previously untrained, eumenorrheic women [body fat: 24.8 ± 1.0 (SE) %]. Data were collected during the follicular (FPh) and the luteal phases (LPh). Posttraining FPh and LPh tests were held the day after the last day of a 5-day period of training on a cycle ergometer. Total 2-hydroxyestrogens (2-OHE) averaged 200 ± 29 pg/ml during the FPh and 420 ± 54 pg/ml during the LPh ( P < 0.05). Levels of total 2-methoxyestrogens (2-MeOE) were 237 ± 32 pg/ml during the FPh and 339 ± 26 pg/ml during the LPh ( P< 0.05). After training, although the plasma levels of 2-OHE significantly decreased (−21%; P < 0.05) during the LPh, the actual CE formation (as estimated from the 2-OHE-to-total estrogens ratio) increased (+29%; P < 0.05). CE activity, as expressed by the 2-MeOE-to-2-OHE ratio, showed significantly higher values in both phases (FPh, +14%; LPh, +13%; P < 0.05). At the same time, resting levels of norepinephrine (NE) were increased by 42% ( P < 0.05). CE strongly inhibit biological decomposition of NE by catechol- O-methyltransferase (COMT). Results of the present study suggest that, in response to training, CE are increasingly competing with the enzyme COMT, thus preventing premature NE deactivation.
Determination of airway and tissue resistances after antigen and methacholine in nonhuman primates
Authors: Madwed Jeffrey B. , Jackson Andrew C.
Published: December 2017

Madwed, Jeffrey B., and Andrew C. Jackson.Determination of airway and tissue resistances after antigen and methacholine in nonhuman primates. J. Appl. Physiol. 83(5): 1690–1696, 1997.—Antigen challenge of Ascaris suum-sensitive animals has been used as a model of asthma in humans. However, no reports have separated total respiratory resistance into airway (Raw) and tissue (Rti) components. We compared input impedance (Zin) and transfer impedance (Ztr) to determine Raw and Rti in anesthetized cynomolgus monkeys under control and bronchoconstricted conditions. Zin data between 1 and 64 Hz are frequency dependent during baseline conditions, and this frequency dependence shifts in response to A. suum or methacholine. Thus it cannot be modeled with the DuBois model, and estimates of Raw and Rti cannot be determined. With Ztr, baseline data were much less variable than Zin in all monkeys. After bronchial challenge with A. suum or methacholine, the absolute amplitude of the resistive component of Ztr increased and its zero crossing shifted to higher frequencies. These data can estimate Raw and Rti with the six-element DuBois model. Therefore, in monkeys, Ztr has advantages over other measures of lung function, since it provides a methodology to separate estimates of Raw and Rti. In conclusion, Ztr shows spectral features similar to those reported in healthy and asthmatic humans.
Role of endogenous female hormones in hypoxic chemosensitivity
Authors: Tatsumi Koichiro , Pickett Cheryl K. , Jacoby Christopher R. , Weil John V. , Moore Lorna G.
Published: December 2017

Tatsumi, Koichiro, Cheryl K. Pickett, Christopher R. Jacoby, John V. Weil, and Lorna G. Moore. Role of endogenous female hormones in hypoxic chemosensitivity. J. Appl. Physiol. 83(5): 1706–1710, 1997.—Effective alveolar ventilation and hypoxic ventilatory response (HVR) are higher in females than in males and after endogenous or exogenous elevation of progesterone and estrogen. The contribution of normal physiological levels of ovarian hormones to resting ventilation and ventilatory control and whether their site(s) of action is central and/or peripheral are unclear. Accordingly, we examined resting ventilation, HVR, and hypercapnic ventilatory responses (HCVR) before and 3 wk after ovariectomy in five female cats. We also compared carotid sinus nerve (CSN) and central nervous system translation responses to hypoxia in 6 ovariectomized and 24 intact female animals. Ovariectomy decreased serum progesterone but did not change resting ventilation, end-tidal[Formula: see text], or HCVR (all P = NS). Ovariectomy reduced the HVR shape parameter A in the awake (38.9 ± 5.5 and 21.2 ± 3.0 before and after ovariectomy, respectively, P < 0.05) and anesthetized conditions. The CSN response to hypoxia was lower in ovariectomized than in intact animals (shape parameter A = 22.6 ± 2.5 and 54.3 ± 3.5 in ovariectomized and intact animals, respectively, P < 0.05), but central nervous system translation of CSN activity into ventilation was similar in ovariectomized and intact animals. We concluded that ovariectomy decreased ventilatory and CSN responsiveness to hypoxia, suggesting that the presence of physiological levels of ovarian hormones influences hypoxic chemosensitivity by acting primarily at peripheral sites.
Recovery of diaphragmatic function in awake sheep after two approaches to thoracic surgery
Authors: Imanaka Hideaki , Kimball William R. , Wain John C. , Nishimura Masaji , Okubo Kenichi , Hess Dean , Kacmarek Robert M.
Published: December 2017

Imanaka, Hideaki, William R. Kimball, John C. Wain, Masaji Nishimura, Kenichi Okubo, Dean Hess, and Robert M. Kacmarek.Recovery of diaphragmatic function in awake sheep after two approaches to thoracic surgery. J. Appl. Physiol. 83(5): 1733–1740, 1997.—Video-assisted thoracoscopic surgery (VATS) is replacing thoracotomy, but no study has addressed the extent or duration of VATS-induced diaphragmatic alteration. We hypothesized that VATS would impair diaphragmatic function less and return diaphragmatic function faster than thoracotomy. In eight sheep, sonomicrometers were randomly implanted on the right costal diaphragm via VATS or thoracotomy. Diaphragmatic resting length, shortening fraction, and respiratory function were measured weekly during quiet breathing (QB) and CO2rebreathing for 4 wk. For VATS, shortening fraction was smallest on postoperative days 1( POD 1) (6.4 ± 3.4 and 12.9 ± 8.7% during QB and 10% CO2rebreathing, respectively) and 7 (6.3 ± 3.4 and 16.9 ± 4.0% during QB and 10% CO2rebreathing, respectively) and recovered by 3 wk (13.2 ± 1.8 and 28.9 ± 8.0% during QB and 10% CO2rebreathing, respectively). For thoracotomy, shortening fraction at 10% CO2rebreathing was smaller on PODs 1, 7, 14 (15.9 ± 7.1, 13.6 ± 5.4, and 19.0 ± 6.9%) than on POD 28 (29.9 ± 8.2%), but not during QB on POD 1 or 7 (7.5 ± 3.8 and 3.4 ± 2.6%) compared with POD 28 (10.7 ± 8.7%). Shortening fraction did not differ between surgeries. There was no group difference in minute ventilation, respiratory rate, transdiaphragmatic pressure, or esophageal and gastric pressures. In conclusion, although shortening fraction recovered faster for VATS, this translated into insignificant functional differences.
Coupled vs. uncoupled pericardial constraint: effects on cardiac chamber interactions
Authors: Takata Masao , Harasawa Yasuhiko , Beloucif Sadek , Robotham James L.
Published: December 2017

Takata, Masao, Yasuhiko Harasawa, Sadek Beloucif, and James L. Robotham. Coupled vs. uncoupled pericardial constraint: effects on cardiac chamber interactions. J. Appl. Physiol. 83(6): 1799–1813, 1997.—The effects of pericardial constraint on cardiac chamber interactions were evaluated by mathematical model analyses based on a novel concept of coupled vs. uncoupled pericardial constraint. We hypothesized that the nature of pericardial constraint can be classified as a “coupled” constraint exerted by uniform liquid pressure or an “uncoupled” constraint exerted by regional surface pressure. The numerical solution of the model of atrioventricular interaction produced the characteristic waveforms in venous flows and right atrial/ventricular pressures in classical pericardial diseases. Coupled constraint accounted for the patterns in cardiac tamponade; uncoupled constraint accounted for those in constrictive pericarditis. Analytic solution of the model of ventricular interdependence demonstrated that coupled constraint (tamponade) produced greater gains in ventricular interdependence, increasing the occurrence of pulsus paradoxus, whereas uncoupled constraint (constriction) produced a greater effective right ventricular elastance, increasing the likelihood of Kussmaul’s sign. Thus the concept of coupled vs. uncoupled constraint may offer a coherent framework to understand the characteristic steady-state and respiratory-induced hemodynamic events in multiple forms of pericardial diseases.
On the mechanism of mucosal folding in normal and asthmatic airways
Authors: Wiggs Barry R. , Hrousis Constantine A. , Drazen Jeffrey M. , Kamm Roger D.
Published: December 2017

Wiggs, Barry R., Constantine A. Hrousis, Jeffrey M. Drazen, and Roger D. Kamm. On the mechanism of mucosal folding in normal and asthmatic airways. J. Appl. Physiol. 83(6): 1814–1821, 1997.—Previous studies have demonstrated that the airway wall in asthma and chronic obstructive pulmonary disease is markedly thickened. It has also been observed that when the smooth muscle constricts the mucosa buckles, forming folds that penetrate into the airway lumen. This folding pattern may influence the amount of luminal obstruction associated with smooth muscle activation. A finite-element analysis of a two-layer composite model for an airway is used to investigate the factors that determine the mucosal folding pattern and how it is altered as a result of changes in the thickness or stiffness of the different layers that comprise the airway wall. Results demonstrate that the most critical physical characteristic is the thickness of the thin inner layer of the model. Thickening of this inner layer likely is represented by the enhanced subepithelial collagen deposition seen in asthma. Other findings show a high shear stress at or near the epithelial layer, which may explain the pronounced epithelial sloughing that occurs in asthma, and steep gradients in pressure that could cause significant shifts of liquid between wall compartments or between the wall and luminal or vascular spaces.
Atrial distension in humans during microgravity induced by parabolic flights
Authors: Videbaek Regitze , Norsk Peter
Published: December 2017

Videbaek, Regitze, and Peter Norsk. Atrial distension in humans during microgravity induced by parabolic flights. J. Appl. Physiol. 83(6): 1862–1866, 1997.—The hypothesis was tested that human cardiac filling pressures increase and the left atrium is distended during 20-s periods of microgravity (μG) created by parabolic flights, compared with values of the 1-G supine position. Left atrial diameter ( n = 8, echocardiography) increased significantly during μG from 26.8 ± 1.2 to 30.4 ± 0.7 mm ( P < 0.05). Simultaneously, central venous pressure (CVP; n = 6, transducer-tipped catheter) decreased from 5.8 ± 1.5 to 4.5 ± 1.1 mmHg ( P < 0.05), and esophageal pressure (EP; n = 6) decreased from 1.5 ± 1.6 to −4.1 ± 1.7 mmHg ( P < 0.05). Thus transmural CVP (TCVP = CVP − EP; n = 4) increased during μG from 6.1 ± 3.2 to 10.4 ± 2.7 mmHg ( P < 0.05). It is concluded that short periods of μG during parabolic flights induce an increase in TCVP and left atrial diameter in humans, compared with the results obtained in the 1-G horizontal supine position, despite a decrease in CVP.
Allometric modeling does not determine a dimensionless power function ratio for maximal muscular function
Authors: Batterham Alan M. , George Keith P.
Published: December 2017

Batterham, Alan M., and Keith P. George. Allometric modeling does not determine a dimensionless power function ratio for maximal muscular function. J. Appl. Physiol. 83(6): 2158–2166, 1997.—In the exercise sciences, simple allometry ( y = axb ) is rapidly becoming the method of choice for scaling physiological and human performance data for differences in body size. The purpose of this study is to detail the specific regression diagnostics required to validate such models. The sum (T, in kg) of the “snatch” and “clean-and-jerk” lifts of the medalists from the 1995 Men’s and Women’s World Weightlifting Championships was modeled as a function of body mass (M, in kg). A log-linearized allometric model (ln T = ln a + bln M) yielded a common mass exponent ( b) of 0.47 (95% confidence interval = 0.43–0.51, P < 0.01). However, size-related patterned deviations in the residuals were evident, indicating that the allometric model was poorly specified and that the mass exponent was not size independent. Model respecification revealed that second-order polynomials provided the best fit, supporting previous modeling of weightlifting data (R. G. Sinclair. Can. J. Appl. Sport Sci. 10: 94–98, 1985). The model parameters (means ± SE) were T = (21.48 ± 16.55) + (6.119 ± 0.359)M − (0.022 ± 0.002)M2( R 2 = 0.97) for men and T = (−20.73 ± 24.14) + (5.662 ± 0.722)M − (0.031 ± 0.005)M2( R 2 = 0.92) for women. We conclude that allometric scaling should be applied only when all underlying model assumptions have been rigorously evaluated.
Letters to the Editor
Authors: Nevill Alan
Published: December 2017

The following is the abstract of the article discussed in the subsequent letter:

Batterham, Alan M., Keith Tolfrey, and Keith P. George. Nevill’s explanation of Kleiber’s 0.75 mass exponent: an artifact of collinearity problems in least squares models? J. Appl. Physiol. 82(2): 693–697, 1997.—Intraspecific allometric modeling (Y = a ⋅ mass b , where Y is the physiological dependent variable and ais the proportionality coefficient) of peak oxygen uptake (V˙o 2peak) has frequently revealed a mass exponent ( b) greater than that predicted from dimensionality theory, approximating Kleiber’s 3/4 exponent for basal metabolic rate. Nevill ( J. Appl. Physiol. 77: 2870–2873, 1994) proposed an explanation and a method that restores the inflated exponent to the anticipated 2/3. In human subjects, the method involves the addition of “stature” as a continuous predictor variable in a multiple log-linear regression model: ln Y = ln a + c ⋅ ln stature + b ⋅ ln mass + ln ε, where c is the general body size exponent and ε is the error term. It is likely that serious collinearity confounds may adversely affect the reliability and validity of the model. The aim of this study was to critically examine Nevill’s method in modelingV˙o 2peak in prepubertal, teenage, and adult men. A mean exponent of 0.81 (95% confidence interval, 0.65–0.97) was found when scaling by mass alone. Nevill’s method reduced the mean mass exponent to 0.67 (95% confidence interval, 0.44–0.9). However, variance inflation factors and tolerance for the log-transformed stature and mass variables exceeded published criteria for severe collinearity. Principal components analysis also diagnosed severe collinearity in two principal components, with condition indexes >30 and variance decomposition proportions exceeding 50% for two regression coefficients. The derived exponents may thus be numerically inaccurate and unstable. In conclusion, the restoration of the mean mass exponent to the anticipated 2/3 may be a fortuitous statistical artifact.
Alterations in myocardial signal transduction due to aging and chronic dynamic exercise
Authors: Roth David A. , White Cynthia D. , Podolin Deborah A. , Mazzeo Robert S.
Published: December 2017

Roth, David A., Cynthia D. White, Deborah A. Podolin, and Robert S. Mazzeo. Alterations in myocardial signal transduction due to aging and chronic dynamic exercise. J. Appl. Physiol.84(1): 177–184, 1998.—Normal aging without disease leads to diminished chronotropic and inotropic responses to catecholamine stimulation, resulting in depressed cardiac function with stress. The purpose of this study was to determine molecular mechanisms for decrements in adrenergic responsiveness of the left ventricle (LV) due to aging and to study the effects of chronic dynamic exercise on signal transduction. We measured β-adrenergic receptor (β-AR) density, adenylyl cyclase (AC) activity, and G-protein content and distribution in LV from 66 male Fischer 344 rats from three age groups that were either sedentary or treadmill trained (60 min/day, 5 days/wk, 10 wk at 75% of the maximal capacity). Final ages were 7 mo (young), 15 mo (middle-age), and 25 mo (old). There was no significant difference in β-AR density among groups as a function of age or training. AC production of adenosine 3′,5′-cyclic monophosphate (cAMP) with the use of five pharmacological stimulations revealed that old sedentary myocardium had depressed basal, receptor-dependent, G-protein-dependent, and AC catalyst stimulation (30–43%) compared with hearts from young and middle-age sedentary rats. Training did not alter AC activity in either middle-age or old groups but did increase G-protein-dependent cAMP production in young myocardium (12–34%). Immunodetectable concentrations of stimulatory and inhibitory G proteins (Gs and Gi, respectively) showed 43% less total Gs with similar Gicontent in hearts from old sedentary compared with middle-age sedentary rats. When compared with young sedentary animals, Gicontent was 39 and 50% higher in middle-age sedentary and old sedentary myocardium, respectively. With age, there was a significant shift in the α-subunit of Gs distribution from cytosolic fractions of LV homogenates to membrane-bound fractions (8–12% redistribution in middle-age sedentary vs. old sedentary). The most significant training effect was a decrease in Gi content in hearts from old trained rats (23%), which resulted in values comparable with young sedentary rats and reduced the Gi/Gs ratio by 27% in old-rat LV. We report that age-associated reductions in cardiovascular β-adrenergic responsiveness correspond with alterations in postreceptor adrenergic signaling rather than with a decrease in receptor number. Chronic dynamic exercise partially attenuates these reductions through alterations in postreceptor elements of cardiac signal transduction.
Older adults can maximally activate the biceps brachii muscle by voluntary command
Authors: De Serres Sophie J. , Enoka Roger M.
Published: December 2017

De Serres, Sophie J., and Roger M. Enoka. Older adults can maximally activate the biceps brachii muscle by voluntary command. J. Appl. Physiol. 84(1): 284–291, 1998.—Because some of the decline in strength with age may be explained by an impairment of muscle activation, the purpose of this study was to determine the activation level achieved in biceps brachii by older adults during a maximum voluntary contraction (MVC). This capability was assessed with two superimposition techniques: one calculated the activation level that was achieved during an MVC, and the other provided an estimate of the expected MVC force based on extrapolation with submaximal forces. The activation level in biceps brachii was incomplete (<100%) for the young ( n = 16) and elderly ( n = 16) subjects, with the elderly subjects exhibiting the greater deficit. In contrast, there was no difference between the measured and expected MVC forces for either group of subjects, whether the extrapolation involved a third-order polynomial or linearization of the data. Because of the lower signal-to-noise ratio associated with the measurement of activation level and the greater number of measurements that contributed to the estimate of the expected MVC force, we conclude that the older adults were able to achieve complete activation of the biceps brachii muscle during an MVC.
A modified Bessel filter for amplitude demodulation of respiratory electromyograms
Authors: Platt Ronald S. , Hajduk Eric A. , Hulliger Manuel , Easton Paul A.
Published: December 2017

Platt, Ronald S., Eric A. Hajduk, Manuel Hulliger, and Paul A. Easton. A modified Bessel filter for amplitude demodulation of respiratory electromyograms. J. Appl. Physiol. 84(1): 378–388, 1998.—We studied a device that is commonly used for amplitude demodulation of respiratory muscle electromyograms (EMG). This device contains a rectifier and a low-pass filter called a modified third-order Paynter filter. We characterized this filter and found that it has good transient characteristics that suit its task as an EMG demodulator, but it has poor high-frequency attenuation that passes interfering, higher frequency components to the output waveform. Therefore, we designed and constructed a new filter with transient characteristics that are comparable to those of the modified Paynter filter but with superior high-frequency attenuation. This new filter is a modified seventh-order Bessel filter. We also identified a simple technique to convert an existing modified Paynter filter back to an original Paynter filter. The original Paynter filter has a wider pass band than the modified Paynter filter but superior stop-band attenuation.