Structural failures of the blood-gas barrier and the epithelial-epithelial cell connections in the different vascular regions of the lung of the domestic fowl, Gallus gallus variant domesticus, at rest and during exercise (original) (raw)
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The FASEB Journal, 2012
Complete blood-gas barrier breaks (BGBBs) and epithelial-epithelial cells connections breaks (E-ECCBs) were enumerated in the lungs of free range chickens, Gallus gallus variant domesticus after vascular perfusion at different pressures. The E-ECCBs surpassed the BGBBs by a factor of ~2. This showed that the former parts of the gas exchange tissue were structurally weaker or more vulnerable to failure than the latter. The differences in the numbers of BGBBs and E-ECCBs in the different regions of the lung supplied with blood by the 4 main branches of the pulmonary artery (PA) corresponded with the diameters of the blood vessels, the angles at which they bifurcated from the PA, and the positions along the PA where they branched off. Most of the BGBBs and the E-ECCBs occurred in the regions supplied by the accessory-and the caudomedial branches: the former is the narrowest branch and the first blood vessel to separate from the PA while the latter is the most direct extension of the PA and is the widest. The E-ECCBs appeared to separate and fail from tensing of the blood capillary walls, as the perfusion-and intramural pressures increased. Compared to the mammalian lungs on which data are available, i.e., those of the rabbit, the dog, and the horse, the blood-gas barrier of the lung of free range chickens appears to be substantially stronger for its thinness.
The FASEB Journal, 2014
Complete blood-gas barrier breaks (BGBBs) and epithelial-epithelial cells connections breaks (E-ECCBs) were enumerated in the lungs of free range chickens, Gallus gallus variant domesticus after vascular perfusion at different pressures. The E-ECCBs surpassed the BGBBs by a factor of ~2. This showed that the former parts of the gas exchange tissue were structurally weaker or more vulnerable to failure than the latter. The differences in the numbers of BGBBs and E-ECCBs in the different regions of the lung supplied with blood by the 4 main branches of the pulmonary artery (PA) corresponded with the diameters of the blood vessels, the angles at which they bifurcated from the PA, and the positions along the PA where they branched off. Most of the BGBBs and the E-ECCBs occurred in the regions supplied by the accessory-and the caudomedial branches: the former is the narrowest branch and the first blood vessel to separate from the PA while the latter is the most direct extension of the PA and is the widest. The E-ECCBs appeared to separate and fail from tensing of the blood capillary walls, as the perfusion-and intramural pressures increased. Compared to the mammalian lungs on which data are available, i.e., those of the rabbit, the dog, and the horse, the blood-gas barrier of the lung of free range chickens appears to be substantially stronger for its thinness.
Biomedical engineering and computational biology, 2013
Complete blood-gas barrier breaks (BGBBs) and epithelial-epithelial cells connections breaks (E-ECCBs) were enumerated in the lungs of free range chickens, Gallus gallus variant domesticus after vascular perfusion at different pressures. The E-ECCBs surpassed the BGBBs by a factor of ~2. This showed that the former parts of the gas exchange tissue were structurally weaker or more vulnerable to failure than the latter. The differences in the numbers of BGBBs and E-ECCBs in the different regions of the lung supplied with blood by the 4 main branches of the pulmonary artery (PA) corresponded with the diameters of the blood vessels, the angles at which they bifurcated from the PA, and the positions along the PA where they branched off. Most of the BGBBs and the E-ECCBs occurred in the regions supplied by the accessory- and the caudomedial branches: the former is the narrowest branch and the first blood vessel to separate from the PA while the latter is the most direct extension of the P...
Effect of prolonged heavy exercise on pulmonary gas exchange in horses
Journal of Applied Physiology
Effect of prolonged, heavy exercise on pulmonary gas exchange in athletes. J. Appl. Physiol. 85(4): 1523-1532, 1998.-During maximal exercise, ventilation-perfusion inequality increases, especially in athletes. The mechanism remains speculative. We hypothesized that, if interstitial pulmonary edema is involved, prolonged exercise would result in increasing ventilation-perfusion inequality over time by exposing the pulmonary vascular bed to high pressures for a long duration. The response to shortterm exercise was first characterized in six male athletes [maximal O 2 uptake (V O 2 max ) ϭ 63 ml · kg Ϫ1 · min Ϫ1 ] by using 5 min of cycling exercise at 30, 65, and 90% V O 2 max . Multiple inert-gas, blood-gas, hemodynamic, metabolic rate, and ventilatory data were obtained. Resting log SD of the perfusion distribution (log SD Q ) was normal [0.50 Ϯ 0.03 (SE)] and increased with exercise (log SD Q ϭ 0.65 Ϯ 0.04, P Ͻ 0.005), alveolar-arterial O 2 difference increased (to 24 Ϯ 3 Torr), and end-capillary pulmonary diffusion limitation occurred at 90% V O 2 max . The subjects recovered for 30 min, then, after resting measurements were taken, exercised for 60 min at ϳ65% V O 2 max . O 2 uptake, ventilation, cardiac output, and alveolararterial O 2 difference were unchanged after the first 5 min of this test, but log SD Q increased from 0.59 Ϯ 0.03 at 5 min to 0.66 Ϯ 0.05 at 60 min (P Ͻ 0.05), without pulmonary diffusion limitation. Log SD Q was negatively related to total lung capacity normalized for body surface area (r ϭ Ϫ0.97, P Ͻ 0.005 at 60 min). These data are compatible with interstitial edema as a mechanism and suggest that lung size is an important determinant of the efficiency of gas exchange during exercise. multiple inert-gas elimination technique; interstitial pulmonary edema
Comparative physiology of the pulmonary blood-gas barrier: the unique avian solution
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2009
High vascular and airway pressures increase interstitial protein mRNA expression in isolated rat lungs. J. Appl. Physiol. 83(5): 1697-1705.-We hypothesized that wall stresses produced by high peak airway (Paw) and venous (Ppv) pressures would increase mRNA levels for structural proteins of the interstitial matrix in isolated rat lungs. Groups of lungs (n ϭ 6) were perfused for 4 h at a peak Paw of 35 cmH 2 O (HiPaw), cyclical peak Ppv of 28 cmH 2 O (HiPv), or baseline vascular and airway pressures (LoPress). In two separate groups, comparable peak pressures increased capillary filtration coefficient fourfold in each group. Northern blots were probed for mRNA of ␣ 1 (I), ␣ 1 (III), and ␣ 2 (IV) procollagen chains, laminin B chain, fibronectin, and transforming growth factor- 1 , and densities were normalized to 18S rRNA. mRNA was significantly higher in the HiPv group for type I (4.3-fold) and type III (3.8-fold) procollagen and laminin B chain (4.8-fold) and in the HiPaw group for type I (2.4-fold) and type IV (4.5-fold) procollagen and laminin B chain (2.3-fold) than in the LoPress group. Only fibronectin mRNA was significantly increased (3.9-fold) in the LoPress group relative to unperfused lungs. Estimated wall stresses were highest for alveolar septa in the HiPaw group and for capillaries in the HiPv group. The different patterns of mRNA expression are attributed to different regional stresses or extent of injury. collagen; fibrosis; pulmonary hypertension; barotrauma; fibronectin; vascular permeability
Maximal rowing has an acute effect on the blood-gas barrier in elite athletes
Journal of applied physiology (Bethesda, Md. : 1985), 2003
The purpose of the study was to evaluate the effects of maximal exercise on the integrity of the alveolar epithelial membrane using the clearance rate of aerosolized 99mTc-labeled diethylenetriaminepentaacetic acid as an index for the permeability of the lung blood-gas barrier. Ten elite rowers (24.3 +/- 4.6 yr of age) completed two 20-min pulmonary clearance measurements immediately after and 2 h after 6 min of all-out rowing (initial and late, respectively). All subjects participated in resting control measurements on a separate day. For each 20-min measurement, lung clearance was calculated for 0-7 and 10-20 min. Furthermore, scintigrams were processed from the initial and late measurements of diethylenetriaminepentaacetic acid clearance. Compared with control levels, the pulmonary clearance measurement after rowing was increased from 1.2 +/- 0.5 to 2.4 +/- 1.0%/min (SD) at 0-7 min (P < 0.01) and from 0.8 +/- 0.3 to 1.5 +/- 0.4%/min at 10-20 min (P < 0.0005), returning to r...
Cardio-pulmonary function values in double-muscled cattle during muscular exercise
Veterinary Research Communications, 1988
Cardio-pulmonary function values in double-muscled cattle during muscular exercise. Veterinary Research Communications, 12 (65), 407416. Eleven double-muscled calves of the Belgian White and Blue breed and eleven Friesian calves have been investigated at rest, during exercise on a treadmill (11% incline; speed 1.3 m.secl) and 10 and 30 minutes after the end of this exercise. Blood gases and acid-base status were determined in mixed venous and arterial blood sampled from the pulmonary and the carotid artery respectively. Expired gases were collected in a balloon. The time of collection, volume of expired gases and fractional O2 and CO, concentrations in expired gases were measured. In double-muscled calves, inadequate oxygen intake and carbon dioxide elimination were demonstrated by the increase in the carbon dioxide tension (PaCO,) and in the hydrogen ion concentration [H+]= and the decrease in the oxygen tension (PaOJ in arterial blood during exercise. In Friesian calves, an adequate increase in oxygen intake occurred and no acidosis was recorded. A metabolic acidosis explained by only a 1.5fold increase in the cardiac output and by the small increase in haemoglobin concentration was recorded in double-muscled calves. It was concluded that some aspects of the cardio-pulmonary and metabolic responses to exercise in double-muscled calves can be related to their inability to greatly increase their O2 consumption.
Effects of graded exercise on bronchial blood flow and airway dimensions in sheep
Pulmonary Pharmacology & Therapeutics, 2007
Exercise stimulus-response relationships for airway blood supply and dimensions have not been described in mammalian species. These relationships are vital for postulates concerning integrated reflex factors normally controlling the airways and which may underlie the asthma syndromes of exercise. This study defines airways stimulus-response relationships in exercising sheep. Ewes between 35 and 40 kg were instrumented at left thoracotomy under thiopentone/isoflurane general anaesthesia. Pulsed Doppler ultrasonic transducers were mounted on the bronchial artery, and transit-time plus single-crystal sonomicrometers on the left main bronchus. These recorded simultaneously and continuously bronchial blood flow (Q br) and conductance (C br), bronchial circumference (Circ br) and wall thickness (Th br). In Protocol 1 (P1), four sheep ran duplicate 5 min protocols on a horizontal treadmill at continuous step-up-and-down speeds of 1 min duration, namely, 0.8, 1.6, 2.2, 1.6 and 0.8 mph (moderate exercise), followed by 10 min recovery. In P2, four sheep ran duplicate 2 min protocols at constant 4 mph (strenuous exercise), and in P3, one sheep ran duplicate protocols each of 3 min at 2.2, 4.4 and 6 mph (severe exercise). Regression analysis and repeated measures ANOVA were used to assess differences between times, runs and exercise intensity. In P1, airway effects were directly related to graded exercise effort sustained over 5 min. Peak effects occurred at 2.2 mph, except for Th br. Heart rate and P a rose (to 156% and 111% of resting, respectively), and Q br and C br fell (to 83% and 75%; both Po0.001). Circ br fell to 96% (P ¼ 0.02), and Th br rose at low speeds early and late, and thinned at the highest speed. In P2 and P3 for all variables the steady-state effects were systematically greater than for P1 (4.4 mph: C br to 43%, Circ br to 93%; 6.6 mph: C br to 25%, Circ br to 82%). There was no significant recovery hyperaemia, but there was residual post-exercise bronchoconstriction. The exercise stimulus-response relationships from rest to a maximal 6 mph for sheep airway circumference and its bronchial circulation are inverse and functionally constrictor.
A century of exercise physiology: lung fluid balance during and following exercise
European Journal of Applied Physiology, 2022
Purpose This review recalls the principles developed over a century to describe trans-capillary fluid exchanges concerning in particular the lung during exercise, a specific condition where dyspnea is a leading symptom, the question being whether this symptom simply relates to fatigue or also implies some degree of lung edema. Method Data from experimental models of lung edema are recalled aiming to: (1) describe how extravascular lung water is strictly controlled by "safety factors" in physiological conditions, (2) consider how waning of "safety factors" inevitably leads to development of lung edema, (3) correlate data from experimental models with data from exercising humans. Results Exercise is a strong edemagenic condition as the increase in cardiac output leads to lung capillary recruitment, increase in capillary surface for fluid exchange and potential increase in capillary pressure. The physiological low microvascular permeability may be impaired by conditions causing damage to the interstitial matrix macromolecular assembly leading to alveolar edema and haemorrhage. These conditions include hypoxia, cyclic alveolar unfolding/folding during hyperventilation putting a tensile stress on septa, intensity and duration of exercise as well as inter-individual proneness to develop lung edema. Conclusion Data from exercising humans showed inter-individual differences in the dispersion of the lung ventilation/perfusion ratio and increase in oxygen alveolar-capillary gradient. More recent data in humans support the hypothesis that greater vasoconstriction, pulmonary hypertension and slower kinetics of alveolar-capillary O2 equilibration relate with greater proneness to develop lung edema due higher inborn microvascular permeability possibly reflecting the morpho-functional features of the air-blood barrier.
Journal of Microscopy, 2008
In mammals, surface macrophages (SMs) play a foremost role in protecting the respiratory system by engulfing and destroying inhaled pathogens and harmful particulates. However, in birds, the direct defense role(s) that SMs perform remains ambiguous. Paucity and even lack of SMs have been reported in the avian respiratory system. It has been speculated that the pulmonary defenses in birds are inadequate and that birds are exceptionally susceptible to pulmonary diseases. In an endeavour to resolve the existing controversy, the phagocytic capacities of the respiratory SMs of the domestic fowl and the rat were compared under similar experimental conditions by exposure to polystyrene particles. In cells of equivalent diameters (8.5 μ m in the chicken and 9.0 μ m in the rat) and hence volumes, with the volume density of the engulfed polystyrene particles, i.e. the volume of the particles per unit volume of the cell (SM) of 23% in the chicken and 5% in the rat cells, the avian cells engulfed substantially more particles. Furthermore, the avian SMs phagocytized the particles more efficiently, i.e. at a faster rate. The chicken erythrocytes and the epithelial cells of the airways showed noteworthy phagocytic activity. In contrast to the rat cells that did not, 22% of the chicken erythrocytes phagocytized one to six particles. In birds, the phagocytic efficiencies of the SMs, erythrocytes, and epithelial cells may consolidate pulmonary defense. The assorted cellular defenses may explain how and why scarcity of SMs may not directly lead to a weak pulmonary defense. The perceived susceptibility of birds to respiratory diseases may stem from the human interventions that have included extreme genetic manipulation and intensive management for maximum productivity. The stress involved and the structural-functional disequilibria that have occurred from a 'directed evolutionary process', rather than weak immunological and cellular immunity, may explain the alleged vulnerability of the avian gas exchanger to diseases.