CHANGES TAKING PLACE IN RESPIRATORY EFFICIENCY OF ISOLATED FLIGHT MUSCLE SARCOSOMES ASSOCIATED WITH AGE OF BLOWFLY CALLIPHORA ERYTHROCEPHALA

Sarcosomal efficiency in relation to age of the fly was estimated by measuring, oxidative phosphorylation (PO ratios), respiratory control, and ATP-ase activity in the absence and presence of 2:4 dinitrophenol [DNP]. There was a significant decline in P : O ratios with increasing age, from a mean of 1.73 with sarcosomes from 10 day-old flies, to 1.26 with sarcosomes 70-90 day-old flies. With [alpha]-glycerophosphate as substance, respiratory control ratios between 1.5 and 1.6 were obtained with young flies, whereas 65 day-old flies gave low values (RCI 1.14). There was also a significant decline in the DNP factor with increasing age. All results indicated "tighter coupling" in sarcosomes from young flies. Results are discussed in relation to previous observations on the physiology of the whole animal and tissue studies.