A convenient micromethod for the estimation of mitochondrial cytochrome C

Specificity of acute effects of Cd on renal function

Renal reabsorption of a typical low-molecular weight protein (cytochrome c) by rats was compared in controls and in rats acutely poisoned with CdCl2 (20 mumol/kg i.p., together with 300 mumol mercaptoethanol), HgCl2 (3 mg/kg i.m.), or NiCl2 (10 mg/kg i.p.). The effects of these metals on reabsorption of filtered cytochrome c were expressed in terms of changes induced in total protein excretion and in urinary concentrating ability. On this basis, only Cd exerted an acute specific effect on transport of cytochrome c, similar to its production of low molecular weight proteinuria following chronic exposure. At the time of the experiments the animals contained only low Cd levels in the renal cortex (7 micrograms/g). We conclude that the acutely injected rat can serve at least to some extent as a valid model for the study of Cd nephrotoxicity and that cytochrome c is a useful probe for the study of Cd-induced low molecular weight proteinuria.

The isolation of mitochondria from dipteran flight muscle

Procedures for the isolation of mitochondria from dipteran flight muscle have been investigated in an attempt to determine the extent and to identify the causes of deterioration associated with isolation. In the light of the results obtained isolation procedures have been improved by minimising mechanical damage, avoiding the development of anoxic conditions, and by the use of an isolation medium of a more physiological nature, containing the potassium salt of an organic anion as the principal osmoeffector, phosphate as the principal buffer, and low concentrations of free Mg2+. The oxidative capacity of mitochondria isolated by the improved method is adequate to support the in vivo requirements of the flight system.