Rate equation for creatine kinase predicts the in vivo reaction velocity: 31P NMR surface coil studies in brain, heart, and skeletal muscle of the living rat.

Brain, heart, and skeletal muscle contain four different creatine kinase isozymes and various concentrations of substrates for the creatine kinase reaction. To identify if the velocity of the creatine kinase reaction under cellular conditions is regulated by enzyme activity and substrate concentrations as predicted by the rate equation, we used 31P NMR and spectrophotometric techniques to measure reaction velocity, enzyme content, isozyme distribution, and concentrations of substrates in brain, heart, and skeletal muscle of living rat under basal or resting conditions. The total tissue activity of creatine kinase in the direction of MgATP synthesis provided an estimate for Vmax (23.

Reduction of pulsed gradient settling time in the superconducting magnet of a magnetic resonance instrument.

The implementation of electronic compensation for eddy currents to reduce the gradient settling times on a superconducting magnet is described. Field plots inside the magnet indicate the importance of assessing the field changes at several positions in the magnet. The effect of an asymmetry between the gradient coil system and the cryostat is demonstrated.

Sodium transport and phosphorus metabolism in sodium-loaded yeast: simultaneous observation with sodium-23 and phosphorus-31 NMR spectroscopy in vivo.

Simultaneous 23Na and 31P NMR spectra were obtained from a number of yeast suspensions. Prior to NMR spectroscopy, the yeast cells were Na-loaded: this replaced some of the intracellular K+ with Na+. These cells were also somewhat P-deficient in that they had no polyphosphate species visible in the 31P NMR spectrum.

Pulse sequence design for volume selective excitation in magnetic resonance.

The design of a pulse sequence for volume localization in magnetic resonance spectroscopy is described in detail. The sequence is based on the volume selective excitation technique (VSE) proposed by Aue et al. [J.