Size of pores of Kohn: influence of transpulmonary and vascular pressures.
J Appl Physiol Respir Environ Exerc Physiol
; 51(3): 739-45, 1981 Sep.
Article
em En
| MEDLINE
| ID: mdl-6895745
ABSTRACT
We investigated the influence of transpulmonary (Ptp) and vascular pressures on the size of the pores of Kohn in primary alveolar septa. Dogs lungs, perfused and ventilated in situ, were rapidly frozen with Freon 22 in zone II or III conditions following deflation to Ptp of 5, 15, or 25 cmH2O. Frozen samples were freeze-substituted for transmission electron microscopy. Five fields containing at least one pore each were selected randomly from each section of tissue, and the minimum diameter visible in the cut section was measured. For both zone II and III conditions, as Ptp increased, mean pore size increased. The mean pore size under zone III conditions was 1.2015, 1.788, and 2.249 micrometer for Ptp of 5, 15, and 25 cmH2O, respectively. For zone 2 conditions, the corresponding values were 1.1438, 1,8757, and 2.08 micrometer. For both zones II and III, increasing capillary hydrostatic pressure had no significant effect on pore size. The results support the notion that alveolar pores can increase collateral ventilation by dynamically stretching as Ptp increases. Capillary pressure does not influence pore size probably because of collagen fibers, which surround the pore lumen. Presumably, these fibers resist encroachment of capillaries on the pore lumen as vascular pressures increase.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Alvéolos Pulmonares
/
Pressão Sanguínea
/
Pulmão
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Appl Physiol Respir Environ Exerc Physiol
Ano de publicação:
1981
Tipo de documento:
Article