High energy phosphates in a red and a white muscle of the rat.

Abstract

Previously we reported that ATP as well as phosphoryl creatine decreased by 10% under ether anesthesia vs. barbiturate anesthesia in rat leg muscle. This decrease did not occur when the sciatic nerve was severed. We therefore suggested that the decrease of high energy phosphates under ether was due to an activation of muscle fibers, presumably of red ones. In this study this postulate is proved by measuring adenine nucleotides and phosphoryl creatine in a red and a white muscle, —m. pyramidalis and m. adductor magnus of the rat. The conditions compared are: 1. Barbiturate (Inactin) anesthesia, 2. Ether anesthesia, 3. Ether-anesthesia plus destroying the segments L 4/5 of the spinal cord, 4. Electrical stimulation under Inactin-anesthesia, and 5. “Thermal contracture”. Under Inactin anesthesia the ATP content is slightly lower in the red muscle (6230±177 nanomoles per gram fresh weight) than in the white (6860±122 nanomoles per gram fresh weight); the phosphoryl creatine contents do not differ significantly between the two muscles. Unter ether anesthesia the ATP content is lowered by 25% vs. Inactin anesthesia in the red muscle while the ATP content remained unchanged under ether in the white muscle. Phosphoryl creatine is lowered by 10% under ether vs. Inactin anesthesia in the red muscle, while it is unchanged in the white muscle. After destroying the segments L4/5 of the spinal cord ATP and phosphoryl creatine remain unchanged under ether vs. Inactin anesthesia in the red as well as in the white muscle. One minute tetanic contraction as produced by direct electrical stimulation results in a 35% decrease of phosphoryl creatine in both the red and the white muscle with matching increments of free creatine. Under the same condition neither ATP nor ADP are significantly affected in the white muscle. In the red muscle the total adenine nucleotide decreases by 11% due to a 16% fall of ATP wich is not stoichiometrically matched by a 16% increase of ADP. “Thermal contracture” (repeated freezing and thawing in situ) causes considerable decreases of ATP and of phosphoryl creatine in the red as well as in the white muscle. The results indicate that the known virtual disagreement with the Lohmann concept of the ATP and phosphoryl creatine decrements in the activated state is less prominent in red than in white muscle. The data are consistent with the postulate that a neurally mediated activation of red fibers occurs under ether anesthesia.