Medical College of Wisconsin
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Temporal pattern of pulmonary gas exchange during exercise in ponies. J Appl Physiol Respir Environ Exerc Physiol 1984 Sep;57(3):760-7



Pubmed ID




Scopus ID

2-s2.0-0021198446   12 Citations


We characterized the temporal patterns of pulmonary O2 consumption (VO2) and CO2 excretion (VCO2) in exercising ponies. We also assessed the cardiac, ventilatory, and hematologic contributions to the VO2-VCO2 changes during exercise. At five moderate treadmill work loads in normal ponies, VO2 and VCO2 generally increased progressively throughout the 1st min reaching, respectively, approximately 95 and 80% of steady state by 45-60 s. Between 1 and 1.5 min, Vo2 and Vco2 were either stable or they decreased 300-500 ml, but then each increased slightly, reaching steady-state levels between 3 and 5 min. The increases to steady-state VO2 and VCO2 were clearly not monoexponential. Arterial O2 content (CaO2) increased during exercise, presumably because of mobilization of stored splenic erythrocytes. For example, after 1 and 6 min at 6 mph 3% grade, CaO2 had increased above rest by 3.2 and 4.9 vol%, respectively (P less than 0.05). Hyperventilation during exercise decreased arterial CO2 content (CaCO2) below rest. For example, after 1 and 6 min at 6 mph 3% grade, CaCO2 had decreased below rest by 2.8 and 1 vol%, respectively (P less than 0.05). At all work loads, heart rate (HR) and presumably cardiac output increased rapidly during the 1st min, reaching a maximum by approximately 45 s. HR then decreased (P less than 0.05), reaching a steady state by 3 min of exercise. During the first 1.5 min of exercise in carotid body-denervated (CBD) ponies, the changes in VO2, HR, and CaO2 were temporally delayed relative to the normals, whereas the changes in VCO2 and CaCO2 were relatively augmented.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List

Forster HV, Pan LG, Bisgard GE, Dorsey SM, Britton MS


Hubert V. Forster PhD Professor in the Physiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Carotid Body
Energy Metabolism
Heart Rate
Physical Exertion
Pulmonary Gas Exchange
Time Factors
jenkins-FCD Prod-468 69a93cef3257f26b866d455c1d2b2d0f28382f14