UNASSIGNED: Closed respirometry is a commonly used method to measure gas exchange in animals due to its apparent simplicity. Typically, the rates of @entity3612 uptake and @entity3158 excretion ( @entity4962 and V  @entity3158 , respectively) are assumed to be in steady state, such that the measured rates of gas exchange equal those at tissue level. In other words, the @entity1576 ( @entity1576 ) is assumed to equal the respiratory quotient (RQ). However, because the gas concentrations change progressively during closure, the animal inspires air with a progressively increasing @entity3158 concentration and decreasing @entity3612 concentration. These changes will eventually affect gas exchange causing the @entity3612 and @entity3158 stores within the animal to change. Because of the higher solubility/capacitance of @entity3158 in the tissues of the body, V  @entity3158 will be more affected than @entity4962 , and we hypothesize therefore that @entity1576 will become progressively underestimated as closure time is prolonged. This hypothesis was addressed by a combination of experimental studies involving closed respirometry on @entity16654 ( @entity16654 ) as well as mathematical models of gas exchange. We show that increased closed duration of the respirometer reduces @entity1576 by up to 13%, and these findings may explain previous reports of @entity1576 values being below 0.7. Our model reveals that the maximally possible reduction in @entity1576 is determined by the storage capacity of the body for @entity3158 (product of size and specific capacitance) relative to the respirometer storage capacity. Furthermore, modeling also shows that pronounced ventilatory and circulatory response to hypercapnia can alleviate the reduction in @entity1576 .

Closed system respirometry may underestimate tissue gas exchange and bias the @entity1576 ( XXXX ).

@entity4962 :: ('CHEBI:30046', 'Chemical') :: ['V  O2'] @entity16654 :: ('51751', 'Species') :: ['ball pythons', 'Python regius'] @entity3158 :: ('D002245', 'Chemical') :: ['CO2'] @entity1576 :: ('MESH:D012131', 'Disease') :: ['respiratory gas exchange ratio', 'RER'] @entity3612 :: ('D013481', 'Chemical') :: ['O2']
@entity1576 :: (MESH:D012131,Disease) :: ['RER']
