Measurements of capillary dimensions and blood volume in rapidly frozen lungs.

Major differences in the pulmonary circulation between birds and mammals

“…Because increasing pulmonary arterial pressure at constant venous pressure, and increasing pulmonary venous pressure at constant pulmonary arterial pressure, result in an increase in capillary pressure, the resulting fall in pulmonary vascular resistance is generally believed to be caused by recruitment and distension of pulmonary capillaries. Using morphometric techniques on rapidly frozen dog lung, Glazier et al (1969) showed that increases in capillary pressure both open up previously closed capillaries, and increased the caliber of capillaries already open.…”

“…The corresponding conditions in the dog are shown in Fig 3B. This micrograph from Glazier et al (1969) was prepared by rapid freezing the lung, and the section was taken 24 cm above the Zone 1-2 junction where pulmonary arterial pressure was equal to alveolar pressure. Therefore the transmural pressure of the capillaries was about 24 cmH 2 O in the direction to compress them, which was somewhat less than the capillary transmural pressure in the adjoining chicken lung section.…”

“…Note that there are clearly more open capillaries containing red blood cells compared to that found in zone 1, but the appearance is patchy and in some of the alveolar walls the capillaries are still closed. It has been shown by morphometry that as the pulmonary arterial pressure is increased under these conditions there is an approximately linear increase in the number of red blood cells per unit length of alveolar wall (Glazier et al 1969).…”

Quantitative assessment of water content of human lung: A study on open lung biopsy specimen.

“…The lung water consisted of interstitial water, blood water and intracellular water. Drainage of blood from the lung cannot remove the blood in capillaries, and the capillary blood is distributed unevenly within the lung (Glazier et al 1969;Maseri et al 1972). Therefore the blood water should be exclude from the lung to determine the lung water content.…”

Regional Vascular Response to Hypoxia in the Lungs of Anaesthetised Sheep

“…This discussion is difficult to resolve satisfactorily as the contribution of the alveolar capillary network to pulmonary vascular resistance is undefined (West, 1972). It may be expected that capillaries in the smaller alveoH contribute a smaller vascular resistance than those in the larger alveoli where the tension in these walls appears to be greater (Glazier et al, 1969). The increasing contribution of alveolar vessels to pulmonary vascular resistance has been postulated to explain the familiar U-shaped plot of total pulmonary vascular resistance versus lung volume.…”