. Author manuscript; available in PMC: 2015 Apr 1.

Published in final edited form as: Eur J Appl Physiol. 2014 Jan 8;114(4):847–858. doi: 10.1007/s00421-013-2810-9

Table I.

Absolute resting phosphate metabolite concentrations determined by ³¹P-MRS (A) and biochemically (B) before and at various time points (one week, two weeks, three weeks) after spinal cord contusion in rats. C) Kinetic ³¹P-MRS averaged data at the end of electrical muscle stimulation (End ex) and recovery from exercise. All data are expressed as mean ± standard error.

A) Resting metabolite concentrations determined by ³¹P-MRS
	Pre SCI	1wk SCI	2wk SCI	3wk SCI
[Pi](mM)	2.46±0.16	2.51±0.18	2.55±0.11	2.21±0.18
[PCr](mM)	26.34±0.58	20.07±0.78^*	28.73±0.56	27.73±0.43
[Pi]/[PCr]	0.09±0.01	0.12±0.01	0.09±0.004	0.08±0.01
pH	7.14±0.01	7.18±0.01^*	7.17±0.01^*	7.17±0.01^*
[Pi][ADP]/[ATP]	13.95±1.55	21.31±2.0^*	19.26±1.32^*	14.44±1.14
B) Biochemical quantification of absolute metabolite concentrations
[ATP](mM)	6.72±0.64	6.03±1.03	-	6.85±1.14
[TCr](mM)	44.9±1.3	36.2±3.7^*	-	45.5±4.7
C) Kinetic metabolite concentrations determined by ³¹P-MRS data
k_PCr (min⁻¹)	0.65±0.05	0.50±0.06^*	0.67±0.05	0.63±0.07
Vmax (mM/min)	17.52±1.52	11.64±1.42^*	16.25±1.28	15.97±1.59
End ex pH	7.02±0.01	6.98±0.02^*	6.99±0.02	7.00±0.01
Rest – End ex pH (pH units)	0.12 units	0.20 units	0.18 units	0.17 units
End ex [PCr]	18.98±0.92	11.87±0.97^*	19.72±0.9	18.84±0.71
End ex [ADP] (μM)	47.11±4.46	55.95±6.32	55.14±5.37	54.43±2.55
End ex [ADP][Pi]/[ATP]	67.77±7.18	78.27±6.28	76.10±13.12	77.06±6.25

Statistically different from pre injury (<0.05). Abbreviations: [Pi] = inorganic phosphate; [PCr] = phosphocreatine; [ADP] = free cystolic adenosine diphosphate; [ATP] = metabolically determined adenosine triphosphate; [ADP][Pi]/[ATP] = phosphorylation ratio; k_PCr = rate constant; 1/k = time constant [TCr] = absolute concentrations of biochemically determined total muscle creatine; V_max = mitochondrial oxidative capacity based on recovery rate constant; mM= mmol/L cell water.