Optical isometric force transducer for measurement of rat skeletal muscle contraction in the NMR spectrometer.

Abstract

In order to measure force of contraction of the rat gastrocnemius muscle in the NMR spectrometer with a simultaneous observation of 31P NMR spectra, an optical force transducer was constructed using gratings and optical fibers. Muscle contraction was accurately recorded in the spectrometer without interfering with NMR measurements. The half height width of the phosphocreatine (PCr) peak in the presence or absence of the transducer was 5 Hz. Decrease in PCr and increase in inorganic phosphate (Pi) in the muscle were successfully followed during monitoring of the force developed during exercise. The change in the PCr:(PCr + Pi) ratio correlated well with the time-force integral from the optical force transducer. In general, there was no interference with the 31P NMR spectrum when the transducer was attached to rat leg, so this optical force transducer should prove valuable for studying muscle physiology in the NMR spectrometer.