A morphometric study of the lungs of different sized bats: correlations between structure and function of the chiropteran lung

1991 ◽  
Vol 333 (1266) ◽  
pp. 31-50 ◽  
Keyword(s):  
Surface Area ◽  
Body Mass ◽  
Lung Volume ◽  
Capillary Blood ◽  
The Body ◽  
Capillary Endothelium ◽  
Diffusing Capacity ◽  
Blood Gas ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood

1. The lungs of four species of bats, Phyllostomus hastatus (PH, mean body mass, 98 g), Pteropus lylei (PL,456 g), Pteropus alecto (PA, 667 g), and Pteropus poliocephalus (PP, 928 g) were analysed by morphometric methods. These data increase fivefold the range of body masses for which bat lung data are available, and allow more representative allometric equations to be formulated for bats. 2. Lung volume ranged from 4.9 cm 3 for PH to 39 cm 3 for PP. The volume density of the lung parenchyma (i.e. the volume proportion of the parenchyma in the lung) ranged from 94% in PP to 89% in PH. Of the components of the parenchyma, the alveoli composed 89% and the blood capillaries about 5% . 3. The surface area of the alveoli exceeded that of the blood—gas (tissue) barrier and that of the capillary endothelium whereas the surface area of the red blood cells as well as that of the capillary endothelium was greater than that of the tissue barrier. PH had the thinnest tissue barrier (0.1204 μm) and PP had the thickest (0.3033 μm). 4. The body mass specific volume of the lung, that of the volume of pulmonary capillary blood, the surface area of the blood-gas (tissue) barrier, the diffusing capacity of the tissue barrier, and the total morphometric pulmonary diffusing capacity in PH all substantially exceeded the corresponding values of the pteropid species (i.e. PL, PA and PP). This conforms with the smaller body mass and hence higher unit mass oxygen consumption of PH, a feature reflected in the functionally superior gas exchange performance of its lungs. 5. Morphometrically, the lungs of different species of bats exhibit remarkable differences which cannot always be correlated with body mass, mode of flight and phylogeny. Conclusive explanations of these pulmonary structural disparities in different species of bats must await additional physiological and flight biomechanical studies. 6. While the slope, the scaling factor (b), of the allometric equation fitted to bat lung volume data (b = 0.82) exceeds the value for flight Vo 2max , (b = 0.70), those for the surface area of the blood-gas (tissue) barrier (b = 0.74), the pulmonary capillary blood volume (b = 0.74), and the total morphometric lung diffusing capacity for oxygen (b = 0.69) all correspond closely to the Vo 2max , value. 7 Allometric comparisons of the morphometric pulmonary parameters of bats, birds and non-flying mammals reveal that superiority of the bat lung over that of the non-flying mammal. However, the bat parameters relative to those of non-flying mammals deteriorate towards the higher body size range, because of the generally steeper slopes of the equations for non-flying mammals. Allometric comparisons also reveal that small-size bats have, in general, better adapted lungs than birds of equivalent size but at the higher body mass scale, bats are generally inferior to birds.

An allometric study of pulmonary morphometric parameters in birds, with mammalian comparisons

1989 ◽  
Vol 326 (1231) ◽  
pp. 1-57 ◽  
Keyword(s):  
Surface Area ◽  
Body Mass ◽  
Plasma Layer ◽  
Strongly Correlated ◽  
Diffusing Capacity ◽  
Blood Gas ◽  
Pulmonary Diffusing Capacity ◽  
Total Lung Volume ◽  
Pulmonary Capillary ◽  
Pulmonary Capillary Blood

Comprehensive pulmonary morphometric data from 42 species of birds representing ten orders were compared with those of other vertebrates, especially mammals, relating the comparisons to the varying biological needs of these avian taxa. The total lung volume was strongly correlated with body mass. The volume density of the exchange tissue was lowest in the charadriiform and anseriform species and highest in the piciform, cuculiform and passeriform species. The surface area of the blood-gas (tissue) barrier, the volume of the pulmonary capillary blood and the total morphometric pulmonary diffusing capacity were all strongly correlated with body mass. The harmonic mean thickness of both the blood—gas (tissue) barrier and the plasma layer were weakly correlated with body mass. The mass-specific surface area of the blood—gas (tissue) barrier (surface area per gram body mass) and the surface density of the blood—gas (tissue) barrier (i.e. its surface area per unit volume of exchange tissue) were inversely correlated (though weakly) with body mass. The passeriform species exhibited outstanding pulmonary morphometric adaptations leading to a high specific total diffusing capacity per gram body mass, consistent with the comparatively small size and energetic mode of life which typify passeriform birds. The relatively inactive, ground-dwelling domestic fowl ( Gallus gallus ) had the lowest pulmonary diffusing capacity per gram body mass. The specific total lung volume is about 27 % smaller in birds than in mammals but the specific surface area of the blood-gas (tissue) barrier is about 15% greater in birds. The ratio of the surface area of the tissue barrier to the volume of the exchange tissue was also much greater in the birds (170-305 %). The harmonic mean thickness of the tissue barrier was 56—67 % less in the birds, but that of the plasma layer was about 66% greater in the birds. The pulmonary capillary blood volume was also greater (22%) in the birds. Except for the thickness of the plasma layer, these morphometric parameters all favour the gas exchange capacity of birds. Consequently, the total specific mean morphometric pulmonary diffusing capacity for oxygen was estimated to be about 22% greater in birds than in mammals of similar body mass. This estimate was obtained by employing oxygen permeation constants for mammalian tissue, plasma and erythrocytes, as avian constants were not then available. Recalculations using recent values for the rate of oxygen uptake by avian whole blood indicate that the superiority of the avian pulmonary diffusing capacity for oxygen is even greater, the value for birds exceeding that of mammals by about 82%. However, because of the small numbers of some of the avian species investigated and the lack of representatives of many important groups of birds, our allometric computations should be regarded as essentially a preliminary basis for comparing the pulmonary morphometric characteristics of birds and mammals. It is suggested that the greater physiological efficiency of the avian pulmonary system compared with that of mammals can be attributed partly to the pulmonary morphometric differences between these two vertebrate classes. Other major factors are the cross-current relation of parabronchial gas and blood, the auxiliary countercurrent relation of air capillary gas and blood, and the bellows action of the air sacs.

Effect of pressure suit inflation on pulmonary capillary blood volume

1961 ◽  
Vol 16 (4) ◽  
pp. 674-678 ◽  
Author(s):  
Joseph C. Ross ◽  
Gene E. Maddock ◽  
Glen D. Ley
Keyword(s):  
Blood Volume ◽  
Capillary Blood ◽  
The Body ◽  
Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Capillary Bed ◽  
Pulmonary Capillary Blood Volume ◽  
Intravascular Pressure

Compression of the lower part of the body by an aviator's G suit produces acute pulmonary vascular engorgement and increases pulmonary vascular pressure. In previous studies, pulmonary diffusing capacity for carbon monoxide (Dl) was increased by this procedure, presumably due to increase in the pulmonary capillary blood volume (Vc), and apparently indicating that the pulmonary capillary bed can be passively dilated by increased intravascular pressure. In the present study, the effect of G-suit inflation on Dl was again studied in 12 normal subjects, but also with determinations of Dl at different alveolar O2 tensions so that Vc and the true pulmonary membrane diffusing capacity (Dm) could be calculated. Studies were made in each subject with the suit on, uninflated and then inflated. With suit inflation, Dl was increased in all 12 subjects (27%), Vc was increased in 11 subjects (33%), and Dm was increased in 10 subjects (21%). These studies show that the pulmonary capillary bed can be passively dilated by increased intravascular pressure, but it is not possible to distinguish between the two possible mechanisms, dilatation of open capillaries or opening of previously closed ones. Submitted on December 22, 1960

Temporal course of gas exchange and mechanical compensation after right pneumonectomy in immature dogs

1996 ◽  
Vol 80 (4) ◽  
pp. 1304-1312 ◽  
Author(s):  
S. Takeda ◽  
E. Y. Wu ◽  
M. Ramanathan ◽  
A. S. Estrera ◽  
C. C. Hsia
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Lung Volume ◽  
Pulmonary Blood Flow ◽  
Capillary Blood ◽  
Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Capillary Blood Volume

To determine the temporal progression and magnitude of functional compensation in immature dogs raised to maturity after extensive lung resection, we performed right pneumonectomy (R-Pnx) or right thoracotomy without pneumonectomy (Sham) in matched foxhounds at 2 mo of age. At 4, 8, 20, 40, and 60 wk after surgery, static transpulmonary pressure-lung volume relationships were determined. Lung diffusing capacity, membrane diffusing capacity, pulmonary capillary blood volume, pulmonary blood flow, septal lung tissue volume, and lung volumes were measured simultaneously by a rebreathing technique. During maturation, total lung capacity, lung volume at a given distending pressure, and compliance were lower in the R-Pnx group than in the Sham group (P < 0.05). Pulmonary viscous resistance at maturity was elevated after R-Pnx. There were no significant differences in total lung diffusing capacity, membrane diffusing capacity, pulmonary capillary blood volume, pulmonary blood flow, and septal lung tissue volume between groups. Compensation of alveolar-capillary gas exchange was complete by 4-8 wk after R-Pnx, but compensation of mechanical properties remained incomplete throughout maturation. Relative magnitude of compensation after R-Pnx was greater in immature dogs than in adult dogs studied previously by similar techniques.

Pulmonary diffusing capacity, capillary blood volume, and cardiac output during sustained microgravity

1993 ◽  
Vol 75 (1) ◽  
pp. 15-26 ◽  
Author(s):  
G. K. Prisk ◽  
H. J. Guy ◽  
A. R. Elliott ◽  
R. A. Deutschman ◽  
J. B. West
Keyword(s):  
Cardiac Output ◽  
Surface Area ◽  
Blood Volume ◽  
Capillary Blood ◽  
Diffusing Capacity ◽  
Principal Mechanism ◽  
Pulmonary Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood

We measured pulmonary diffusing capacity (DL), diffusing capacity per unit lung volume, pulmonary capillary blood volume (Vc), membrane diffusing capacity (Dm), pulmonary capillary blood flow or cardiac output (Qc), and cardiac stroke volume (SV) in four subjects exposed to 9 days of microgravity (weightlessness, 0 G). The same subjects were studied standing and supine numerous times preflight and in the week immediately after return from space. DL in microgravity was elevated (28%) compared with preflight standing values and was higher than preflight supine because of the elevation of both Vc (28%) and Dm (27%). The elevation in Vc was comparable to that measured supine in 1 G, but the increase in Dm was in sharp contrast to the supine value (which was unchanged). We postulate that, in 0 G, pulmonary capillary blood is evenly distributed throughout the lung, providing for uniform capillary filling, leading to an increase in the surface area available for diffusion. By contrast, in the supine 1-G state, the capillaries are less evenly filled, and although a similar increase in blood volume is observed, the corresponding increase in surface area does not occur. DL and its subdivisions showed no adaptive changes from the first measurement 24 h after the start of 0 G to 8 days later. Similarly, there were no trends in the postflight data, suggesting that the principal mechanism of these changes was gravitational. The increase in Dm suggests that subclinical pulmonary edema did not result from exposure to 0 G. Qc was modestly increased (18%) inflight and decreased (9%) post-flight compared with preflight standing. Compared with preflight standing, SV was increased 46% inflight and decreased 14% in the 1st wk postflight. There were temporal changes in Qc and SV during 0 G, with the highest values recorded at the first measurement, 24 h into the flight. The lowest values of Qc and SV occurred on the day of return.

scholarly journals Pulmonary tissue volume, cardiac output, and diffusing capacity in sustained microgravity

1997 ◽  
Vol 83 (3) ◽  
pp. 810-816 ◽  
Author(s):  
Sylvia Verbanck ◽  
Hans Larsson ◽  
Dag Linnarsson ◽  
G. Kim Prisk ◽  
John B. West ◽  
...  
Keyword(s):  
Capillary Blood ◽  
Diffusing Capacity ◽  
Pulmonary Tissue ◽  
Tissue Volume ◽  
Pulmonary Capillary ◽  
Interstitial Pulmonary Edema ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Tissue Volume ◽  
Pulmonary Capillary Blood Volume

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.

scholarly journals Are there sex differences in the capillary blood volume and diffusing capacity response to exercise?

2017 ◽  
Vol 122 (3) ◽  
pp. 460-469 ◽  
Author(s):  
Melissa M. Bouwsema ◽  
Vincent Tedjasaputra ◽  
Michael K. Stickland
Keyword(s):  
Blood Volume ◽  
Sex Difference ◽  
Transit Time ◽  
Capillary Blood ◽  
Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Response To Exercise ◽  
Pulmonary Transit Time

Previous work suggests that women may exhibit a greater respiratory limitation in exercise compared with height-matched men. Diffusion capacity (DlCO) increases with incremental exercise, and the smaller lungs of women may limit membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc) in response to the increased oxygen demand. We hypothesized that women would have lower DlCO, DlCO relative to cardiac output (DlCO/Q̇), Dm, Vc, and pulmonary transit time, secondary to lower Vc at peak exercise. Sixteen women (112 ± 12% predicted relative V̇o2peak) and sixteen men (118 ± 22% predicted relative V̇o2peak) were matched for height and weight. Hemoglobin-corrected diffusing capacity (DlCO), Vc, and Dm were determined via the multiple-[Formula: see text] DlCO technique at rest and during incremental exercise up to 90% of V̇o2peak. Both groups increased DlCO, Vc, and Dm with exercise intensity, but women had 20% lower DlCO ( P < 0.001), 18% lower Vc ( P = 0.002), and 22% lower Dm ( P < 0.001) compared with men across all workloads, and neither group exhibited a plateau in Vc. When expressed relative to alveolar volume (Va), the between-sex difference was eliminated. The drop in DlCO/Q̇ was proportionally less in women than men, and mean pulmonary transit time did not drop below 0.3 s in either group. Women demonstrate consistently lower DlCO, Vc, and Dm compared with height-matched men during exercise; however, these differences disappear with correction for lung size. These results suggest that after differences in lung volume are accounted for there is no intrinsic sex difference in the DlCO, Vc, or Dm response to exercise. NEW & NOTEWORTHY Women demonstrate lower diffusing capacity-to-cardiac output ratio (DlCO/Q̇), pulmonary capillary blood volume (Vc), and membrane diffusing capacity (Dm) compared with height-matched men during exercise. However, these differences disappear after correction for lung size. The drop in DlCO/Q̇ was proportionally less in women, and pulmonary transit time did not drop below 0.3 s in either group. After differences in lung volume are accounted for, there is no intrinsic sex difference in DlCO, Vc, or Dm response to exercise.

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