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IL‐6 Administration Increases the Exercise Pressor Reflex
Author(s) -
Copp Steven,
Stone Audrey,
Kaufman Marc
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.1054.8
Subject(s) - hindlimb , reflex , medicine , endocrinology , myokine , peripheral , femoral artery , skeletal muscle , chemistry
IL‐6 is both a pro‐inflammatory cytokine released from macrophages as well as an anti‐inflammatory myokine released from contracting skeletal muscle. Administration of IL‐6 and the soluble form of its receptor (sIL‐6r) has been shown to increase peripheral afferent excitability in response to noxious stimuli. That finding prompted us to test the hypothesis that in decerebrate, unanesthetized rats co‐injection of 50 ng IL‐6 and 50 ng sIL‐6r into the arterial supply of the hindlimb would increase the exercise pressor reflex. We found that after 1 hr co‐injection of IL‐6/sIL‐6r (n=8) modestly increased the peak pressor responses to static (control: 13.5±2.6 mmHg, IL‐6/sIL‐6r: 17.3±2.4 mmHg; p<0.05) and intermittent (control: 9.6±1.9 mmHg, IL‐6/sIL‐6r: 15.3±3.8 mmHg; p<0.05) contractions of the hindlimb muscles. Co‐injection of IL‐6/sIL‐6r had no effect on the peak cardioaccelerator or the popliteal artery blood flow responses to static or intermittent hindlimb muscle contractions. Tension‐time indices were similar between control and IL‐6/sIL‐6r. In five additional rats intra‐arterial hindlimb injection of 50 ng of soluble gp130, which neutralizes the actions of IL‐6/sIL‐6r, prevented the IL‐6/sIL‐6r‐induced increases in the peak pressor responses to static (control: 15.8±3.1 mmHg, sgp130+IL‐6/sIL‐6r: 13.4±2.0 mmHg; p>0.05) and intermittent (control: 10.4±1.8 mmHg, sgp130+IL‐6/sIL‐6r: 9.3±2.2 mmHg; p>0.05) contractions. Moreover, intravenous injection of 50 ng of IL‐6/sIL‐6r (n=4) had no effect on the peak pressor responses to static or intermittent hindlimb muscle contractions. We conclude that IL‐6/sIL‐6r co‐injected into the arterial supply of the hindlimb increased the exercise pressor reflex evoked by static and intermittent hindlimb muscle contractions. Funding: NIH HL‐096570, AR‐059397.