title: Influence of altitude and caffeine during rest and exercise on plasma levels of proenkephalin peptide F.
abstract: The purpose of this study was to examine the resting and exercise response patterns of plasma Peptide F immunoreactivity (ir) to altitude exposure (4300 m) and caffeine ingestion (4 mg.kg b.w.-1). Nine healthy male subjects performed exercise tests to exhaustion (80-85% VO2max) at sea level (50 m), during an acute altitude exposure (1 hr, hypobaric chamber, 4300 m) and after a chronic (17-day sojourn, 4300 m) altitude exposure. Using a randomized, double-blind/placebo experimental design, a placebo or caffeine drink was ingested 1 hour prior to exercise. Exercise (without caffeine) significantly (p less than 0.05) increased plasma Peptide F ir values during exercise at chronic altitude only. Caffeine ingestion significantly increased plasma Peptide F ir concentrations during exercise and in the postexercise period at sea level. Conversely caffeine ingestion at altitude resulted in significant reductions in the postexercise plasma Peptide F ir values. The results of this study demonstrate that the exercise and recovery response patterns of plasma Peptide F ir may be significantly altered by altitude exposure and caffeine ingestion. These data support further study examining relationships between Peptide F (and other enkephalin-containing polypeptides) and epinephrine release in response to these types of physiological stresses.
authors.affiliation: Exercise Physiology Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007.
authors.forename: W J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: P B
authors.initials: PB
authors.lastname: Rock
authors.forename: C S
authors.initials: CS
authors.lastname: Fulco
authors.forename: S E
authors.initials: SE
authors.lastname: Gordon
authors.forename: J P
authors.initials: JP
authors.lastname: Bonner
authors.forename: C D
authors.initials: CD
authors.lastname: Cruthirds
authors.forename: L J
authors.initials: LJ
authors.lastname: Marchitelli
authors.forename: L
authors.initials: L
authors.lastname: Trad
authors.forename: A
authors.initials: A
authors.lastname: Cymerman
mesh_terms: D000328:Adult; D000531:Altitude; D002110:Caffeine / Q000494:pharmacology*; D003429:Cross Reactions; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000097:blood; D004745:Enkephalins / Q000097:blood*; D006801:Humans; D008297:Male; D005082:Physical Exertion; D011498:Protein Precursors / Q000097:blood*; D011863:Radioimmunoassay; D012016:Reference Values
chemical_list: D004745:Enkephalins; D011498:Protein Precursors; C029992:proenkephalin; D002110:Caffeine; D004744:Enkephalin, Methionine; C036452:peptide F