ISSN:
1432-136X
Keywords:
Surfactant
;
Disaturated phospholipids
;
Antiglue
;
Temperature
;
Salamander, Ambystoma tigrinum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Mammalian lungs secrete a mixture of surface-active lipids (surfactant), which greatly reduces the surface tension of the fluid coating the inner lung surface, thereby reducing the risk of collapse upon deflation and increasing compliance upon inflation. During foetal lung maturation, these lipids become enriched in the primary and active ingredient, a disaturated phopholipid. However, disaturated phospholipids exist in their inactive gellike form at temperatures below 37°C and thus are inappropriate for controlling surface tension in the lungs of many ectotherms. We examined the development of the composition and function of the surfactant system of the tiger salamander (Ambystoma tigrinum) during metamorphosis from the fully aquatic larva (termed stage I) through an intermediate air-breathing larval form (stage IV) to the terrestrial adult (stage VII). Biochemical analysis of lung washings from these three life stages revealed a decrease in the percentage of disaturated phospholipid per total phospholipid (23.03 versus 15.92%) with lung maturity. The relative cholesterol content remained constant. The increased level of phospholipid saturation in the fully aquatic larvae may reflect their generally higher body temperature and the higher external hydrostatic compression forces exerted on the lungs, compared to the terrestrial adults. Opening pressure (pressure required for initial lung opening) prior to lavage decreased from larval to adult salamanders (7.96 versus 4.69 cm H2O), indicating a decrease in resistance to opening with lung development. Opening pressure increased after lavage in older aquatic (stage IV) larvae (5.36 versus 9.80 cm H2O) and in the adults (4.69 versus 7.65 cm H2O), indicating that the surfactant system in salamanders may have an antiglue function which prevents apposing epithelial surfaces from adhering together.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00302547
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