title: Temperature and hydration: factor affecting increased recoil of excised rabbit lung.
abstract: We have examined two factors which strongly affect the rate and amount by which excised rabbit lungs become stiffer during mechanical hyperventilation, Pressure-volume (PV) curves were compared before and after 3 hr ventilation (tidal volume 50% TLC, frequency 8/min, end-expiratory pressure of zero) in the temperature range 4 degrees C to 37 degrees C. Lungs were separated into three groups according to method of suspension: (A) floated on saline, (B) floated on mineral oil, and (C) suspended from the trachea. Lung wet/dry weight ratios (W/D) were obtained from groups A and C. In all lungs marked stiffening occurred below 22 degrees C, but the effect diminished sharply between 22 and 28 degrees C. Lungs not in contact with saline (Groups B and C) revealed little change in recoil above 28 degrees C, whereas those in Group A once again tended to become stiff near 37 degrees C. Lung water content in Group A at 37 degrees C was found to be more than double that in Group C. We conclude that two factors can contribute to the stiffening induced by ventilation: (a) temperature maintained below 27-28 degrees C, or (b) excess lung water in combination with temperature above 28 degrees C.
mesh_terms: D000818:Animals; D003681:Dehydration; D066298:In Vitro Techniques; D008168:Lung / Q000033:anatomy & histology / Q000502:physiology; D008170:Lung Compliance; D008176:Lung Volume Measurements; D009929:Organ Size; D011312:Pressure; D011663:Pulmonary Surfactants / Q000502:physiology; D011817:Rabbits; D012121:Respiration, Artificial; D013696:Temperature
chemical_list: D011663:Pulmonary Surfactants