Possible thermoregulatory contributions of plasma B-endorphin during prolonged exercise in humans

Six adult male volunteers of similar body composition and physical fitness were tested to determine plasma immunoreactive β-endorphin (Piβ-EN) response under three conditions of exercise thermoregulatory stress. The experimental protocol consisted of 120 min of stationary upright cycling at 50% Vo₂max under conditions of neutral (24ºC, 50% RH)/euhydration (NE), hot (35°C, 50% RH)/euhydration (HE), and hot/dehydration (HD). Piβ-EN was measured by radioimmunoassay at -30 min, 0 min, and at 15 min intervals thereafter. Change in plasma volume (ΔPV) was measured to determine its effect on Piβ-EN concentration. Preexercise Piβ-EN levels averaged 23.7 ± 2.6 pg•ml⁻¹ in all conditions. The greatest Piβ-EN response occurred at 105 min in HD conditions when levels rose to 43.2 ± 6.9 pg•ml⁻¹. Exercise in HD and HE conditions resulted in significantly (p < 0.05) elevated Piβ-EN above levels observed in NE. ΔPV did not account for more than 10% of Piβ-EN changes at any interval. The Piβ-EN response pattern closely resembled rectal temperature changes in all conditions. These data suggest that conditions of increasing exercise thermoregulatory stress are associated with increasing peripheral β-endorphin concentration.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Education

Department dc:contributor.department

Education

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1983

Author dc:creator

• Kelso, Thomas Benton

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/76020

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/76020