ALDOLASE AND "AMINOACYL ARYLAMIDASE" IN THE DENERVATED RAT GASTROCNEMIUS MUSCLE

Activities of the two enzymes aldolase and "aminoacyl arylamidase" (formerly called leucine aminopeptidase) were determined in rat gastrocnemius muscle 5, 15, and 30 days after denervation. Expression of both activities per unit weight and activities per whole muscle as a percentage of the contralateral control revealed a number of interesting changes. The concentrations of aldolase and "aminoacyl arylamidase" in the contralateral control gastrocnemius muscle were, respectively, 3.07 I.U. (S.E.M. ± 0.18 for 42 animals) and 0.0577 I.U. (S.E.M. ± 0.0030 for 42 animals) per 100 mg wet weight. Both the concentration per unit weight and the content per whole muscle of aldolase were not affected 5 days after neurotomy. At later stages of denervation large losses in aldolase occurred, with the concentration per unit weight being 43% of the control at 15 days and 25% at 30 days. On a whole muscle basis the loss in aldolase was higher than the loss in muscle mass (−85% versus −56% at 15 days and −93% versus −74% at 30 days). The concentration of "aminoacyl arylamidase" per unit weight increased in the denervated muscle (155%, 206%, and 207% of the contralateral control at 5, 15, and 30 days, respectively). The "aminoacyl arylamidase" content of the whole denervated muscle was increased (+ 24%) 5 days after neurotomy; in the later stages of denervation the content decreased, but the decrease was less than that for the muscle mass (−27% versus −56% at 15 days and −43% versus −74% at 30 days).The rapidity and magnitude of the losses of aldolase suggest that denervation of muscle has brought about an increased permeability to this enzyme. The findings for "aminoacyl arylamidase" might be explained on the basis that, immediately after neurotomy, there exists a positive balance between synthesis and the combined effects of catabolism and efflux of the enzyme which changes to a negative balance in the later stages of denervation.