Integrity and Respiration of Red Beet Mitochondria Isolated and Examined in Different Sucrose Concentrations

Abstract

AbstractRespiration experiments with succinate as substrate were made with red beet mitochondria isolated in soluitions containing 0.25 to 1.25 M sucrose. The respiration was measured in reaction media adjusted to be 0.25, 0.50, 0.75 or 1.0 osmolar.With mitochondria isolated in 0.25 or 0.50 M sucrose the rate of succinate oxidation was completely dependent on the osmotic pressure of the reaction medium (decreasing with increasing osmotic pressures). Isolation in 0.75 M sucrose caused a slight after‐effect of the osmotic pressure of the isolation medium, and by isolation in 1.0 M or 1.25, M sucrose the after‐effect was complete. The rate of oxidation was low and independent of the osmotic pressure of the reaction medium.An electron microscopic examination of the state of the mitochondria before and after the respiration period showed that with the conditions used in the present experiments the structure of the mitochondria remained well preserved regardless of the osmotic pressures used.