Investigating the effect of temperature on large aggregate conversion of surfactant from ground squirrels

Abstract

During hibernation, ground squirrels’ body temperature is 5°C. Our research focuses on pulmonary surfactant during hibernation. Surfactant is a phospholipid‐rich material which regulates surface tension at the alveolar surface. A change in surface‐area during respiration leads to conversion of the large aggregate form of surfactant to the small aggregate form. Since temperature affects aggregate conversion, we tested the hypothesis that hibernation led to less conversion of large to small aggregates. Lungs of hibernating and summer active ground squirrels were lavaged to obtain large and small aggregates which were measured by a phospholipid‐phosphorous assay. Surface‐area cycling was performed at 37°C and 4°C to determine large aggregate conversion. Total amounts of large aggregate were higher in hibernating squirrels compared to summer active group. The large aggregates from all groups underwent a conversion to a greater extent at 37°C than at 4°C. Changes in large aggregate pool sizes occur during hibernation, in vitro aggregate conversion data suggests this may be as a result of reduced aggregate conversion at low temperatures.Funding: Canadian Institutes for Health Research.