scholarly journals Inability of tributyltin-induced chloride/hydroxyl exchange to stimulate calcium transport in mitochondria isolated from flight muscle of the sheep blowfly Lucilia cuprina

1978 ◽  
Vol 174 (3) ◽  
pp. 1075-1077 ◽  
Author(s):  
Fyfe L. Bygrave ◽  
Robyn L. Smith
Keyword(s):  
Calcium Transport ◽  
Flight Muscle ◽  
Initial Rate ◽  
Mitochondrial Protein ◽  
Lucilia Cuprina ◽  
Muscle Mitochondria ◽  
Transport In Mitochondria

Tributyltin in the concentration range 1–4μm failed to stimulate Ca2+ transport by Lucilia flight-muscle mitochondria in a medium containing KCl and respiratory substrate but devoid of Pi, despite its promotion of a rapid Cl−/OH− exchange. When 2mm-Pi was present, concentrations of tributyltin greater than 1μm inhibited the initial rate of Ca2+ transport and induced efflux of the ion from the mitochondria in Cl−- or NO3−-containing media. Lower concentrations had little effect. Oligomycin added at up to 10μg/mg of mitochondrial protein had no effect on Ca2+ transport. By contrast, approx. 0.3μm-tributyltin completely inhibited respiration supported by α-glycerophosphate in either the presence or absence of added ADP. The data suggest that tributyltin can inhibit Ca2+ transport in Lucilia flight-muscle mitochondria other than by facilitating a Cl−/OH− exchange or producing an oligomycin-like effect.

Biochemical and Structural Variations in the Flight Muscle Mitochondria of Ageing Blowflies, Calliphora Erythrocephala

1972 ◽  
Vol 10 (2) ◽  
pp. 443-469 ◽  
Author(s):  
M. A. TRIBE ◽  
DOREEN E. ASHHURST
Keyword(s):  
Flight Muscle ◽  
Mitochondrial Protein ◽  
Mitochondrial Proteins ◽  
Mitochondrial Protein Synthesis ◽  
Structural Variations ◽  
Calliphora Erythrocephala ◽  
Muscle Mitochondria ◽  
Mitochondrial Structure ◽  
Age Related ◽  
Age Related Changes

Biochemical investigations with isolated blowfly flight muscle mitochondria show that uncoupling of oxidation and phosphorylation increases with increasing age of the adult fly. Of the two principal substrates used (i.e. α-glycerophosphate and pyruvate), uncoupling is most marked when α-glycerophosphate is used as substrate. Although age-related changes in the structure of the thoracic flight muscle are observed by electron-microscope studies, no obvious degenerative changes take place in either the mitochondrial structure or the myofibrils of old flies. Labelling experiments with [3H] leucine indicate that uncoupling is mainly due to the lack of repair and replacement of mitochondrial proteins. These experiments also show that mitochondrial protein synthesis is important in the maturation of young flies, that is, those between 0 and 4 days old, but is insignificant in the further increase in mitochondrial size observed in older flies, where mitochondrial fusion appears to be more important.

scholarly journals The effect of the coupled oxidation of substrate on the permeability of blowfly flight-muscle mitochondria to potassium and other cations

1972 ◽  
Vol 126 (3) ◽  
pp. 689-700 ◽  
Author(s):  
R. G. Hansford ◽  
A. L. Lehninger
Keyword(s):  
Light Scattering ◽  
Flight Muscle ◽  
Unit Area ◽  
Membrane Surface ◽  
Mitochondrial Matrix ◽  
Exposed Area ◽  
Muscle Mitochondria ◽  
Area 5 ◽  
Choline Phosphate ◽  
Permeant Anion

1. Blowfly flight-muscle mitochondria respiring in the absence of phosphate acceptor (i.e. in state 4) take up greater amounts of K+, Na+, choline, phosphate and Cl-(but less NH4+) than non-respiring control mitochondria. 2. Uptake of cations is accompanied by an increase in the volume of the mitochondrial matrix, determined with the use of [14C]-sucrose and3H2O. The osmolarity of the salt solution taken up was approximately that of the suspending medium. 3. The [14C]sucrose-inaccessible space decreased with increasing osmolarity of potassium chloride in the suspending medium, confirming that the blowfly mitochondrion behaves as an osmometer. 4. Light-scattering studies showed that both respiratory substrate and a permeant anion such as phosphate or acetate are required for rapid and massive entry of K+, which occurs in an electrophoretic process rather than in exchange for H+. The increase in permeability to K+and other cations is probably the result of a large increase in the exposed area of inner membrane surface in these mitochondria, with no intrinsic increase in the permeability per unit area. 5. No increase in permeability to K+and other cations occurs during phosphorylation of ADP in state 3 respiration.

Sign in / Sign up

Export Citation Format

Share Document