D. Negrini et al., PULMONARY INTERSTITIAL PRESSURE AND PROTEOGLYCANS DURING DEVELOPMENT OF PULMONARY-EDEMA, American journal of physiology. Heart and circulatory physiology, 39(6), 1996, pp. 2000-2007
In anesthetized adult rabbits, pulmonary perivascular interstitial pre
ssure (P-ip), measured by micropuncture technique with intact pleural
space, averaged -10.5 +/- 1.9 (SD) cmH(2)O in control conditions, with
a wet-to-dry lung weight ratio (W/D) of 4.8 +/- 0.2, Saline infusion
(120 ml iv over 120 min) induced interstitial edema, increasing P-ip t
o 3.62 +/- 1.6 cmH(2)O with no significant increase in W/D (5.13 +/- 0
.1). For intravenous saline infusion exceeding 140 ml, P-ip decreased
to about-atmospheric pressure with development of severe edema that wa
s characterized by an increase of W/D (>7) with no further change in P
-ip. In a separate set of animals, pulmonary interstitial proteoglycan
s (PGs) were investigated after sequential extraction of the tissue wi
th 0.4 and 4 M guanidinium chloride (GuHCl) under control conditions a
nd with interstitial (100 ml saline load in 100 min) and severe edema
(>200 ml total infusion). The extractability of PGs increased constant
ly with increasing W/D. PG content in total extracts was evaluated by
determination of hexuronate content which was 195.4 +/- 1.5 mu g/g dry
tissue in control lungs, 217.9 +/- 1.6 in interstitial edema, and 316
.4 +/- 2.7 in severe edema. Moreover, edema development was coupled wi
th an increase in efficiency of PG extraction with 0.4 M GuHCl. These
findings suggested a weakening of PG interactions with other component
s of the extracellular matrix (ECM). Electrophoretic and gel-filtratio
n analyses showed that the relative content of PG populations of large
molecular size decreased constantly in 0.4 M GuHCl extract with incre
asing water loading. We propose relating the inflection of P-ip in the
transition from interstitial to severe edema to PG breakdown, which m
ight greatly affect ECM structural organization, including collagen sp
reading and/or rupture of epithelial layer.