Age-related changes in the flight muscle mitochondria from the blowfly Sarcophaga bullata

Flight muscle mitochondria have been isolated from female blowflies (Sarcophaga bullata) of different ages, alpha-Glycerophosphate and pyruvate-proline respiration rates increase during development. Only pyruvate-proline respiration declines toward senescence (30%). This decline can be overcome by ATP-NaHCO3. Cytochrome concentrations and hydrogen peroxide generation rates per protein increase during development but remain constant thereafter. Total NAD+ of metabolically completely oxidized mitochondria decreases during development; a small decline occurs between mature and senescent mitochondria. Respiring young mitochondria do not swell in potassium isethionate, very little in potassium chloride, and relatively slowly in potassium acetate. Mature and senescent mitochondria do swell in these three salts but cannot be differentiated from each other on this basis. None of the preparations swells in sodium chloride, sodium- or potassium Mops. While many differences exist between young and mature mitochondria, only the decline in pyruvate-proline respiration distinguishes mature from senescent mitochondria.