Relation between oxidative metabolism and slow rhythmic potentials in mammalian intestinal muscle.

Abstract

Intact muscle layers separated from the small intestine of the cat were mounted in a specially designed chamber to measure electrical slow waves and NADH fluorescence simultaneously. Cooling the muscle to 17.degree. C eliminated slow waves and simultaneously increased the level of fluorescence. Superfusing the muscle with a N2-bubbled glucose-free Krebs solution decreased the amplitude of slow waves and concomitantly increased fluorescence emission. In both cases, return to normal conditions reversed the effects on both slow waves and fluorescence. When signals were averaged over 30-70 slow waves, a pattern emerged with the fluorescence oscillations in phase with the electric oscillations. The NADH:NAD+ ratio reached a maximum at the most depolarized point of the slow waves and a minimum at the most polarized point between slow waves. This indicates maximum ATP utilization during the repolarization process. The correlation between redox oscillations and electrical slow waves was consistent with previous evidence that slow wave generation was associated with cell metabolism.