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. Author manuscript; available in PMC: 2017 Feb 1.
Published in final edited form as: Growth Horm IGF Res. 2015 Dec 17;26:36–41. doi: 10.1016/j.ghir.2015.12.008

Table 3.

Univariate correlations with irisin and mRNA expression of skeletal muscle FNDC5

Baseline After 3 months Treatment with rhGH
Serum Irisin Skeletal Muscle FNDC5 mRNA Serum Irisin Skeletal Muscle FNDC5 mRNA
ρ P Value ρ P Value ρ P Value ρ P Value
Body Composition Parameters
 BMI (kg/m2) 0.38 .17 −0.15 .68 0.21 .46 0.09 .80
 Iliac Waist (cm) 0.30 .28 −0.24 .51 0.11 .70 0.26 .47
 Total fat mass (kg) 0.39 .16 −0.16 .65 0.09 .76 −0.02 .96
 Total lean mass (kg) −0.14 .62 0.04 .91 0.05 .85 −0.09 .80
Metabolic Parameters
 Peak stimulated GH on GHRH-arginine (μg/L) −0.20 .49 −0.45 .19 -- -- -- --
 IGF-I (μg/L) −0.38 .17 0.08 .83 0.20 .47 −0.22 .53
Energy Parameters
 REE (kcal/day) 0.30 .28 0.32 .37 0.10 .73 0.16 .65
 REE/total lean mass (kcal/day*kg) 0.30 .27 0.26 .47 0.24 .40 0.31 .38
 RQ −0.18 .52 −0.49 .15 −0.15 .58 −0.19 .60
 VO2 (L/min) 0.31 .27 0.37 .29 0.19 .50 0.19 .60
 VCO2 (L/min) 0.19 .50 0.16 .65 0.06 .84 0.03 .93
Mitochondrial Function
 τPC −0.10 .74 −0.28 .43 −0.02 .95 0.19 .60
 ViPCr (mM/min) 0.48 .08 0.79 .006 −0.02 .96 0.22 .53
 PCr (mM)
  Rest 0.48 .08 0.22 .53 0.27 .36 −0.20 .58
  Beginning of recovery 0.48 .08 0.13 .73 0.05 .88 −0.30 .40
  End of recovery 0.38 .18 0.04 .91 0.24 .41 0.02 .96
 ADP (uM)
  Rest −0.64 .01 −0.35 .33 0.03 .93 0.13 .71
  Beginning of recovery −0.75 .002 −0.56 .09 0.31 .29 −0.05 .88
  End of recovery −0.58 .03 −0.25 .49 −0.09 .76 −0.01 .99
mRNA Expression
 IGF-I 0.63 .05 0.81 .005 0.05 .88 0.66 .04
 PGC-1α 0.44 .21 0.68 .03 0.19 .60 0.39 .26
 PPARγ 0.73 .02 0.85 .002 0.01 .99 0.10 .78
 PPARα 0.37 .29 0.62 .05 0.03 .93 0.25 .49
 NRF1 0.54 .11 0.66 .04 −0.07 .85 0.58 .08
 TFAM 0.48 .16 0.79 .007 0.03 .93 0.38 .28

Relationships were assessed by Spearman’s Correlation Coefficient.

Gene expression values are normalized to GAPDH, results are expressed as ratios in arbitrary units

Abbreviations: rhGH, recombinant human growth hormone; FNDC5, fibronectin type III domain-containing protein 5; BMI, body mass index; GHRH, growth hormone releasing hormone; REE, resting energy expenditure; RQ, respiratory quotient, VO2, maximal oxygen consumption; VCO2, carbon dioxide production; PCr, phosphocreatine; τ, recovery time constant; Vi, initial rate; ADP, adenosine diphosphate; PGC-1α, peroxisome proliferator-activated receptor γ coactivator 1α; PPAR, peroxisome proliferator-activated receptor; NRF1, nuclear respiratory factor; TFAM, mitochondrial transfer factor A