title: The influences of temperature and humidity upon the isolated surfactant film of the dog.
abstract: A model of the gas-liquid barrier (surfactant film) of the lung was used to investigate the influence of temperature and of humidification of the gas upon the behaviour of films during rhythmic compression and expansion of their surface. Film behaviour was studied at room temperature or 37 degrees C, and at ambient humidity or high relative humidity. Changes of minimal surface tension (gamma min) and maximal surface tension (gamma max) were followed up to 1000 cycles. At 37 degrees C we measured higher values for gamma min and lower values for gamma max. At room temperature complete humidification does not influence surface tension, but at 37 degrees C gamma min increases. Thus both high temperature and high relative humidity result in sharp rise of gamma min, whereas high temperature alone is responsible for the temporary drop of gamma max. Considering these effects, investigations to study influences of foreign gases and of air pollution upon the surfactant film should be performed under conditions which approach those of the lung as close as possible. The possible influence of CO2 is discussed.
mesh_terms: D000818:Animals; D004285:Dogs; D006813:Humidity; D066298:In Vitro Techniques; D008433:Mathematics; D008954:Models, Biological; D011663:Pulmonary Surfactants / Q000502:physiology*; D012119:Respiration; D013696:Temperature
chemical_list: D011663:Pulmonary Surfactants