Perry 2011 Biochem J

From Bioblast
Publications in the MiPMap
Perry CG, Kane DA, Lin CT, Kozy R, Cathey BL, Lark DS, Kane CL, Brophy PM, Gavin TP, Anderson EJ, Neufer PD (2011) Inhibiting myosin-ATPase reveals a dynamic range of mitochondrial respiratory control in skeletal muscle. Biochem J 437:215-22.

Β» PMID:21554250 Open Access

Perry CG, Kane DA, Lin CT, Kozy R, Cathey BL, Lark DS, Kane CL, Brophy PM, Gavin TP, Anderson EJ, Neufer PD (2011) Biochem J

Abstract: Assessment of mitochondrial ADP-stimulated respiratory kinetics in permeabilized fibre (pfi) bundles is increasingly used in clinical diagnostic and basic research settings. However, estimates of the Km for ADP vary considerably (~20-300 ΞΌM) and tend to overestimate respiration at rest. Noting that pfi bundles spontaneously contract during respiration experiments, we systematically determined the impact of contraction, temperature and oxygenation on ADP-stimulated respiratory kinetics. BLEB (blebbistatin), a myosin II ATPase inhibitor, blocked contraction under all conditions and yielded high Km values for ADP of >~250 and ~80 ΞΌM in red and white rat pfi bundles respectively. In the absence of BLEB, pfi bundles contracted and the Km for ADP decreased ~2-10-fold in a temperature-dependent manner. pfi bundles were sensitive to hyperoxia (increased Km) in the absence of BLEB (contracted) at 30 Β°C but not 37 Β°C. In pfi bundles from humans, contraction elicited high sensitivity to ADP (Km<100 ΞΌM), whereas blocking contraction (+BLEB) and including a phosphocreatine/creatine ratio of 2:1 to mimic the resting energetic state yielded a Km for ADP of ~1560 ΞΌM, consistent with estimates of in vivo resting respiratory rates of <1% maximum. These results demonstrate that the sensitivity of muscle to ADP varies over a wide range in relation to contractile state and cellular energy charge, providing evidence that enzymatic coupling of energy transfer within skeletal muscle becomes more efficient in the working state. β€’ Keywords: Bioenergetics, Blebbistatin, Creatine kinase, Myosin-ATPase, N-benzyltoluene sulfonamide, Skeletal muscle contraction

β€’ O2k-Network Lab: US_NC Greenville_Neufer PD, CA Toronto Perry CG, US_NC_Greenville_Anderson EJ, CA_Antigonish_Kane DA

Labels: MiParea: Respiration 

Organism: Human, Rat  Tissue;cell: Skeletal muscle  Preparation: Permeabilized tissue  Enzyme: Complex I, Complex V;ATP synthase  Regulation: ADP, Inhibitor, Temperature 

Pathway:HRR: Oxygraph-2k 


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