Exogenous surfactant in ischemia/reperfusion: effects on endogenous surfactant pools.
BACKGROUND
Pre-ischemic surfactant treatment attenuates ischemia/reperfusion (I/R) injury. In this study we investigate whether exogenous surfactant acts by influencing endogenous intra-alveolar and intracellular surfactant pools and subtype composition.


METHODS
Rat lungs from control with (C + S) or without (C - S) surfactant treatment and I/R with (I/R + S) or without (I/R - S) surfactant treatment were analyzed. In I/R groups, lungs underwent ischemic storage for 4 hours at 4 degrees C and reperfusion for 60 minutes. The ultrastructure of intra-alveolar and intracellular surfactant forms fixed in their natural localization and microorganization was investigated by light- and electron-microscopic stereology.


RESULTS
Only slight differences in alveolar epithelial Type II cell number or volume and lamellar body parameters were observed. Intra-alveolar surfactant volume was significantly enhanced in C + S and I/R + S. I/R increased inactivated surfactant forms (unilamellar vesicles) in untreated [mean (SD): C - S: 26.0% (8.0%) vs I/R - S: 64.8% (5.5%); p < 0.01], but not in surfactant-treated rats [I/R + S: 23.5% (11.5%); p < 0.01 vs I/R - S]. The increase in unilamellar vesicles was closely correlated with intra-alveolar edema and decreased perfusate oxygenation.


CONCLUSIONS
Attenuation of I/R injury by pre-ischemic exogenous surfactant treatment is mainly based on stabilizing and increasing the active endogenous intra-alveolar surfactant pool.
Institute of Anatomy, University of Bern, Bern, Switzerland. christian.muehlfeld@anatomie.med.uni-giessen.de
Christian
C
Mühlfeld
Laura
L
Becker
Christine
C
Bussinger
Marcel
M
Vollroth
Ragi
R
Nagib
Inga-Marie
IM
Schaefer
Lars
L
Knudsen
Joachim
J
Richter
Navid
N
Madershahian
Thorsten
T
Wahlers
Thorsten
T
Wittwer
Matthias
M
Ochs
D000818:Animals; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D055370:Lung Injury / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control*; D016040:Lung Transplantation; D008297:Male; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D011663:Pulmonary Surfactants / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control*; D013501:Surface-Active Agents / Q000494:pharmacology / Q000627:therapeutic use*
D011663:Pulmonary Surfactants; D013501:Surface-Active Agents