Correlation of lactate and pH in human skeletal muscle after exercise by ¹H NMR

Abstract

We have made in vivo 1H NMR measurements of the time course of pH and lactate in human skeletal muscle after exercise. Spectra were obtained in a 4.7-T 30-cm bore Bruker Biospec spectrometer with a 2.5-cm diameter single surface coil. pH was determined from the shift of the endogenous carnosine H-C2 peak while lactate concentrations were determined by comparison with endogenous total creatine, taken to be 28.5 mM/kg wet wt. Fitting the data shows that the exponential decay of lactate (-0.094 +/- 0.014 min-1. t1/2 = 10.6 min) is slower than that of pH (-0.147 +/- 0.015 min-1, t1/2 = 4.7 min), n = 7 with two different volunteers. These values are significantly different with P less than 0.0005. Relaxation times of lactate and creatine were also measured for lactate quantitation; creatine T1, 1.23 +/- 12 s, T2, 136.2 +/- 26.4 ms (both in resting human muscle); lactate T1 (in postmortem rabbit muscle), 1.0 +/- 11 s and T2, 80 ms (in postexercise human muscle). At the end of intense exercise, the lactate level reached was 25.3 +/- 4.0 mM and the average pH drop was 1.0 pH unit. We discuss the implications of these measurements in conjunction with existing data on other sources of H+ flux, phosphocreatine resynthesis, H+ transport, and contribution of inorganic phosphate to buffering.

Effects of high-intensity training on muscle lactate transporters and postexercise recovery of muscle lactate and hydrogen ions in women

“…These values are close to the H ϩ -to-lactate ratio of 1.6 obtained with the NMR technique and human muscle (36). The greater postexercise decrease in H ϩ than in lactate can be explained by the release of H ϩ from muscle fibers, by not only the lactate-H ϩ transporter, but also by the Na/H ϩ exchanger and HCO 3 Ϫ -dependent systems (28).…”

Observation of intramyocellular lipids by means of1H magnetic resonance spectroscopy

“…However, if no precautions are taken these water-suppressed 1 H MR spectra of human muscle would still be dominated by a large contribution from lipid resonances. It was presumed that only a few metabolites would be visible beneath the resonances of subcutaneous fat (Williams et al 1985;Narayana et al 1988;Barany & Venkatasubramanian, 1989;Bruhn et al 1991;Pan et al 1991). Schick et al (1993) observed two compartments of triacylglycerols with a resonance frequency shift of 0·2 parts per 10 6 (ppm) when they compared the lipid resonances in calf muscle with those in fat tissue.…”

6‐Fluoropyridoxol: A novel probe of cellular pH using 19F NMR spectroscopy

“…NMR offers several potential advantages: continuous non-destructive monitoring of pH in vivo; spatial resolution and simultaneous determination of pH in several compartments [4,5]. NMR has been used to monitor titratable groups of endogenous metabolites on the basis of chemical shift with respect to changing pH; in particular 3'P NMR of inorganic phosphate (Pi) [5,6] or phosphomonoesters [7] or 'H NMR of carnosine [8] or histidine [9]. pH measurement using endogenous metabolites is not always successful owing to crowded spectra, broad lines or low metabolite concentration.…”