Computer determination of perfusion patterns in pulmonary capillary networks

1997 ◽  
Vol 82 (4) ◽  
pp. 1283-1289 ◽  
Author(s):  
Christopher C. Hanger ◽  
Robert G. Presson ◽  
Osamu Okada ◽  
Steven J. Janke ◽  
John J. Watkins ◽  
...  
Keyword(s):  
Computer Program ◽  
Capillary Network ◽  
Alveolar Wall ◽  
Capillary Perfusion ◽  
Capillary Networks ◽  
Pulmonary Capillary ◽  
Computer Determination ◽  
Upstream Pressure

Hanger, Christopher C., Robert G. Presson, Jr., Osamu Okada, Steven J. Janke, John J. Watkins, Wiltz W. Wagner, Jr., and Ronald L. Capen. Computer determination of perfusion patterns in pulmonary capillary networks. J. Appl. Physiol.82(4): 1283–1289, 1997.—Individual pulmonary capillaries are not steadily perfused. By using in vivo microscopy, it can readily be demonstrated that perfusion continually switches between capillary segments and between portions of the network within a single alveolar wall. These changes in capillary perfusion occur even when upstream pressure and flow are constant. Flow switching between capillary segments in the absence of hemodynamic changes in large upstream vessels suggests that capillary perfusion patterns could be random. To calculate the probability that perfusion patterns could occur by chance, it is necessary to know the total number of possible perfusion patterns in a given capillary network. We developed a computer program that can determine every possible perfusion pattern for any given capillary network, and from that information we can calculate whether perfusion of individual segments in the network is random. With the results of the computer program, we have obtained statistical evidence that some capillary segments in a network are nonrandomly perfused.

Blood flow switching among pulmonary capillaries is decreased during high hematocrit

2004 ◽  
Vol 97 (2) ◽  
pp. 522-526 ◽  
Author(s):  
William A. Baumgartner ◽  
Amanda J. Peterson ◽  
Robert G. Presson ◽  
Nobuhiro Tanabe ◽  
Eric M. Jaryszak ◽  
...  
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Average Distance ◽  
Substantial Part ◽  
Alveolar Wall ◽  
Capillary Perfusion ◽  
Capillary Networks ◽  
Pulmonary Capillaries ◽  
Pulmonary Capillary ◽  
Alveolar Capillary

Pulmonary capillary perfusion within a single alveolar wall continually switches among segments, even when large-vessel hemodynamics are constant. The mechanism is unknown. We hypothesize that the continually varying size of plasma gaps between individual red blood cells affects the likelihood of capillary segment closure and the probability of cells changing directions at the next capillary junction. We assumed that an increase in hematocrit would decrease the average distance between red blood cells, thereby decreasing the switching at each capillary junction. To test this idea, we observed 26 individual alveolar capillary networks by using videomicroscopy of excised canine lung lobes that were perfused first at normal hematocrit (31–43%) and then at increased hematocrit (51–62%). The number of switches decreased by 38% during increased hematocrit ( P < 0.01). These results support the idea that a substantial part of flow switching among pulmonary capillaries is caused by the particulate nature of blood passing through a complex network of tubes with continuously varying hematocrit.

Temporal capillary perfusion patterns in single alveolar walls of intact dogs

1994 ◽  
Vol 76 (1) ◽  
pp. 380-386 ◽  
Author(s):  
O. Okada ◽  
R. G. Presson ◽  
P. S. Godbey ◽  
R. L. Capen ◽  
W. W. Wagner
Keyword(s):  
Original Work ◽  
Alveolar Wall ◽  
In Vivo Microscopy ◽  
Capillary Perfusion ◽  
Pulmonary Capillary ◽  
Pulmonary Arterial ◽  
Preferential Pathways ◽  
Variable Group ◽  
Over Time

Pulmonary gas exchange reserve in the form of recruitable capillaries was first described in the 1930s, when in vivo microscopy was used to demonstrate that not all capillaries were perfused during basal conditions and that perfusion of individual capillaries varied over time. These important observations have never been directly confirmed, nor have the hemodynamic causes of the variation been investigated. We used videomicroscopy to record nine consecutive pulmonary capillary perfusion patterns during a 40-min period. Confirming the original work, we found considerable perfusion variation in about one-half of the capillaries. These variations did not correlate with changes in pulmonary arterial pressures or cardiac outputs, suggesting that factors more subtle than large-vessel hemodynamics affected capillary perfusion consistency. In contrast to this variable group, one-half of the capillary segments were consistently perfused during at least eight of the nine observations and were interconnected to form preferential pathways across the alveolar wall.

Effect of luminal angiotensin II and ANP on early and late cortical distal tubule HCO3- reabsorption

1996 ◽  
Vol 271 (5) ◽  
pp. F977-F984 ◽  
Author(s):  
M. L. Barreto-Chaves ◽  
M. Mello-Aires
Keyword(s):  
Angiotensin Ii ◽  
Exchange Resin ◽  
Distal Tubule ◽  
Ang Ii ◽  
Bafilomycin A1 ◽  
Capillary Perfusion ◽  
At1 Receptors ◽  
Luminal Perfusion

Bicarbonate reabsorption was evaluated by stationary microperfusion “in vivo“ early distal (ED) and late distal (LD) segments of at kidney. Intratubular pH was recorded by double-barreled of H+ exchange resin/reference (1 M KCl) microelectrodes for the determination of HCO3- reabsorption. In the presence of angiotensin II (ANG II) (10(-12) M), a significant increase in HCO3- reabsorption was observed both in ED (from 0.930 +/- 0.060 to 2.64 +/- 0.210 nmol.cm-2.s-1 in luminally perfused tubules and from 0.850 +/- 0.040 to 2.03 +/- 0.210 nmol.cm-2.s-1 during capillary perfusion) and LD segments from 0.310 +/- 0.130 to 2.16 +/- 0.151 nmol.cm-2.s-1 during luminal perfusion and from 0.530 +/- 0.031 to 2.16 +/- 0.211 nmol.cm-2.s-1 with capillary perfusion). The addition of the AT1-receptor antagonist losartan (10(-6) M) to luminal perfusion blocked luminal ANG II-mediated stimulation in ED and LD segments. 5-(N,N-hexamethylene)amiloride (10(-4) M) added to luminal perfusion inhibited luminal ANG II-mediated stimulation in ED (by 81%) and LD (by 54%) segments. The addition of bafilomycin A1 (2 x 10(-7) M) to luminal perfusion does not affect luminal ANG II-mediated stimulation in ED segments but reduces it in LD segments (by 33%). During the addition of atrial natriuretic peptide (ANP) (10(-6) M) or ANG II plus ANP in both segments, no significant differences in HCO3- reabsorption were observed. Our results indicate that luminal ANG II acts to stimulate Na+/H+ exchange in ED and LD segments via activation of AT1 receptors, as well as the vacuolar H(+)-adenosinetriphosphatase in LD segments. ANP does not affect HCO3- reabsorption in either ED or LD segments and does not impair the stimulation caused by ANG II.

Vertical gradient of pulmonary capillary transit times

1986 ◽  
Vol 61 (4) ◽  
pp. 1270-1274 ◽  
Author(s):  
W. W. Wagner ◽  
L. P. Latham ◽  
W. L. Hanson ◽  
S. E. Hofmeister ◽  
R. L. Capen
Keyword(s):  
Vertical Gradient ◽  
Substantial Part ◽  
Capillary Perfusion ◽  
Capillary Networks ◽  
Transit Times ◽  
Lower Lung ◽  
Order Of Magnitude ◽  
Anesthetized Dogs ◽  
Magnitude Variation

The key determinants of alveolar capillary perfusion are transit times and the extent of recruitment. Capillaries are known to be heavily recruited in the dependent lung, but there are no direct data that bear on how capillary transit times might be affected by gravity. We directly determined mean capillary transit times on the surface of the upper, middle, and lower lung by measuring the passage of fluorescent dye through the capillaries using in vivo television microscopy. In anesthetized dogs, mean capillary transit times averaged 12.3 s in the upper lung, 3.1 s in the midlung, and 1.6 s in the lower lung. This near order of magnitude variation in speed of blood transit establishes that there is a vertical gradient of capillary transit times in the lung. As expected, dependent capillary networks were nearly fully recruited, whereas relatively few capillaries were perfused in the upper lung. The lengthy transit times and sparsely perfused capillary beds in the upper lung combine to provide a substantial part of pulmonary gas exchange reserve.

Muscular Tissue Engineering: Capillary-Incorporated Hybrid Muscular Tissues in Vivo Tissue Culture

1998 ◽  
Vol 7 (5) ◽  
pp. 435-442 ◽  
Author(s):  
Takahisa Okano ◽  
Takehisa Matsuda
Keyword(s):  
Nude Mice ◽  
Type I Collagen ◽  
Capillary Network ◽  
C2c12 Cells ◽  
Muscular Tissue ◽  
Type I ◽  
Capillary Networks ◽  
Multinucleated Myotubes ◽  
Muscular Tissues

Requirements for a functional hybrid muscular tissue are 1) a high density of multinucleated cells, 2) a high degree of cellular orientation, and 3) the presence of a capillary network in the hybrid tissue. Rod-shaped hybrid muscular tissues composed of C2C12 cells (skeletal muscle myoblast cell line) and type I collagen, which were prepared using the centrifugal cell-packing method reported in our previous article, were implanted into nude mice. The grafts, comprised three hybrid tissues (each dimension, diameter, approximately 0.3 mm, length, approximately 1 mm, respectively), were inserted into the subcutaneous spaces on the backs of nude mice. All nude mice that survived the implantation were sacrificed at 1, 2, and 4 wk after the implantation. The grafts were easily distinguishable from the subcutaneous tissues of host mice with implantation time. The grafts increased in size with time after implantation, and capillary networks were formed in the vicinities and on the surfaces of the grafts. One week after implantation, many capillaries formed in the vicinities of the grafts. In the central portion of the graft, few capillaries and necrotic cells were observed. Mononucleated myoblasts were densely distributed and a low number of multinucleated myotubes were scattered. Two weeks after implantation, the formation of a capillary network was induced, resulting in the surfaces of the grafts being covered by capillaries. Numerous elongated multinucleated myotubes and mononucleated myoblasts were densely distributed and numerous capillaries were observed throughout the grafts. Four weeks after implantation a dense capillary network was formed in the vicinities and on the surfaces of the grafts. In the peripheral portion of the graft, multinucleated myotubes in the vicinities of the rich capillaries were observed. Thus, hybrid muscular tissues in vitro preconstructed was remodeled in vivo, which resulted in facilitating the incorporation of capillary networks into the tissues. © 1998 Elsevier Science Inc.

Real-time in-vivo imaging of pulmonary capillary perfusion using probe-based confocal laser scanning endomicroscopy in pigs

2015 ◽  
Vol 32 (6) ◽  
pp. 392-399 ◽  
Author(s):  
Sybille Gruber ◽  
Isabella Spielauer ◽  
Stefan Böhme ◽  
David Baron ◽  
Klaus Markstaller ◽  
...  
Keyword(s):  
Real Time ◽  
In Vivo Imaging ◽  
Laser Scanning ◽  
Confocal Laser Scanning ◽  
Confocal Laser ◽  
Capillary Perfusion ◽  
Pulmonary Capillary

Distribution of pulmonary capillary transit times in recruited networks

1990 ◽  
Vol 69 (2) ◽  
pp. 473-478 ◽  
Author(s):  
R. L. Capen ◽  
W. L. Hanson ◽  
L. P. Latham ◽  
C. A. Dawson ◽  
W. W. Wagner
Keyword(s):  
Cardiac Output ◽  
Transit Time ◽  
Relative Dispersion ◽  
Capillary Networks ◽  
Transit Times ◽  
Pulmonary Capillary ◽  
Lower Lung ◽  
Anesthetized Dogs ◽  
The Mean

When pulmonary blood flow is elevated, hypoxemia can occur in the fastest-moving erythrocytes if their transit times through the capillaries fall below the minimum time for complete oxygenation. This desaturation is more likely to occur if the distribution of capillary transit times about the mean is large. Increasing cardiac output is known to decrease mean pulmonary capillary transit time, but the effect on the distribution of transit times has not been reported. We measured the mean and variance of transit times in single pulmonary capillary networks in the dependent lung of anesthetized dogs by in vivo videofluorescence microscopy of a fluorescein dye bolus passing from an arteriole to a venule. When cardiac output increased from 2.9 to 9.9 l/min, mean capillary transit time decreased from 2.0 to 0.8 s. Because transit time variance decreased proportionately (relative dispersion remained constant), increasing cardiac output did not alter the heterogeneity of local capillary transit times in the lower lung where the capillary bed was nearly fully recruited.

Capillary perfusion patterns in single alveolar walls

1992 ◽  
Vol 72 (5) ◽  
pp. 1838-1844 ◽  
Author(s):  
O. Okada ◽  
R. G. Presson ◽  
K. R. Kirk ◽  
P. S. Godbey ◽  
R. L. Capen ◽  
...  
Keyword(s):  
Left Atrium ◽  
Elevated Pressure ◽  
Strong Indication ◽  
In Vivo Microscopy ◽  
Capillary Perfusion ◽  
Pulmonary Hemodynamics ◽  
Pulmonary Capillary ◽  
Anesthetized Dogs ◽  
Flowing Blood

We studied capillary perfusion patterns in single alveolar walls through a transparent thoracic window implanted in pentobarbital-anesthetized dogs. The capillaries were maximally opened by brief inflation of a balloon in the left atrium to raise pressure. After the balloon was deflated and pulmonary hemodynamics returned to zone 2 baseline conditions, the capillaries that remained perfused in the observed field were videotaped with the use of in vivo microscopy. The cycle of elevated pressure and baseline observation was repeated three times. Perfusion of different capillaries during each of the observations would imply that the capillaries had characteristics that permitted flow to switch between segments. Perfusion of a specific set of pathways through the network each time would demonstrate that flowing blood sought a unique and repeatable combination of segments, presumably with the least total pathway resistance. We found that the same capillary segments were perfused 79% of the time, a strong indication that a reproducible combination of individual segmental resistances determined the predominant pattern of pulmonary capillary perfusion.

Pulmonary capillary diameters and recruitment characteristics in subpleural and interior networks

1996 ◽  
Vol 80 (5) ◽  
pp. 1568-1573 ◽  
Author(s):  
A. C. Short ◽  
M. L. Montoya ◽  
S. A. Gebb ◽  
R. G. Presson ◽  
W. W. Wagner ◽  
...  
Keyword(s):  
Cross Sections ◽  
Blood Cells ◽  
Alveolar Wall ◽  
Lung Inflation ◽  
Capillary Recruitment ◽  
Cell Counts ◽  
Pulmonary Capillaries ◽  
Pulmonary Capillary ◽  
Wide Range

In vivo microscopic observations of pulmonary capillaries are limited to subpleural networks that are less dense than interior networks. In addition to the density difference, subpleural and interior capillary diameters may differ, although there are conflicting data on this point. We measured the diameters of subpleural and interior capillaries in rats and dogs. Subpleural diameters were 30% larger in rats and 20% larger in dogs. Because diameter and density differences might cause differences in recruitment between subpleural and interior networks, we measured subpleural and interior recruitment by counting the number of red blood cells per 10 microns of alveolar wall in histological cross sections of rapidly frozen rat lungs. Lung inflation pressures of 4, 12, and 25 cmH2O created a wide range of capillary recruitment in different groups of animals. Red blood cell counts for interior and subpleural capillaries moved in parallel and progressively increased as inflation pressures were reduced. These data demonstrate that recruitment in subpleural capillaries accurately reflect recruitment in interior capillaries and validate the use of in vivo microscopic observations of subpleural capillaries to investigate pulmonary capillary recruitment in general.

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