Degeneration of the intersegmental muscles: Alterations in hemolymph during muscle degeneration

Abstract

Alterations in hemolymph constituents during the degeneration of the intersegmental muscles of Manduca sexta and Antheraea polyphemus have been followed by several techniques. An antigen to muscle protein appears in the blood within 5–10 hr after the adult has emerged. When tritiated leucine is injected into developing pupae, labeled protein and amino acids are released into the blood during the period over which the muscles degenerate. Blood levels of lactic dehydrogenase, glutamine-oxaloacetate transaminase, arginine phosphokinase, and aldolase increase approximately 8–9 hr after the insects emerge. The latter two enzymes increase sixfold over preemergence levels, and are highest during the period over which muscle integrity is compromised. The levels of circulating muscle proteins decrease after 30–50 hr. These several data suggest that a fraction of the muscle protein is not digested within the muscle fiber, but is solubilized or otherwise released into the hemolymph, to be digested elsewhere.