Responses of proenkephalin Peptide F to aerobic exercise stress in the plasma and white blood cell biocompartments

William J. Kraemer, Maren S. Fragala, Wendy R.H.Beijersbergen Van Henegouwen, Scott E. Gordon, Jill A. Bush, Jeff S. Volek, N. Travis Triplett, Courtenay Dunn-Lewis, Brett A. Comstock, Tunde K. Szivak, Shawn D. Flanagan, David R. Hooper, Hui Ying Luk, Andrea M. Mastro

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Proenkephalin Peptide F [107-140] is an enkephalin-containing peptide found predominantly within the adrenal medulla, co-packaged with epinephrine within the chromaffin granules. In vivo studies indicate that Peptide F has classic opioid analgesia effects; in vitro studies suggest potential immune cell interactions. In this investigation we examined patterns of Peptide F concentrations in different bio-compartments of the blood at rest and following sub-maximal cycle exercise to determine if Peptide F interacts with the white blood cell (WBC) bio-compartment during aerobic exercise. Eight physically active men (n = 8) performed sub-maximal (80-85% V̇O2Speak) cycle ergometer exercise for 30 min. Plasma Peptide F and WBC Peptide F immunoreactivity were examined pre-exercise, mid-exercise and immediately post-, 5-min post-, 15-min post-, 30-min post- and 60-min post-exercise and at similar time-points during a control condition (30 min rest). Peptide F concentrations significantly (p < 0.05) increased at 5 and 60 min post-exercise, compared to pre-exercise concentrations. No significant increases in Peptide F concentrations in the WBC fraction were observed during or after exercise. However, a significant decrease was observed at 30 min post-exercise. An ultradian pattern of Peptide F distribution was apparent during rest. Furthermore, concentrations of T cells, B cells, NK cells, and total WBCs demonstrated significant changes in response to aerobic exercise. Data indicated that Peptide F was bound in significant molar concentrations in the WBC fraction and that this biocompartment may be one of the tissue targets for binding interactions. These data indicate that Peptide F is involved with immune cell modulation in the white blood circulatory biocompartment of blood.

Original languageEnglish (US)
Pages (from-to)118-124
Number of pages7
StatePublished - Apr 2013

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physiology
  • Endocrinology
  • Cellular and Molecular Neuroscience


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