@entity908 kinase (CK) has a central role in skeletal muscle, acting as a fast energy buffer and shuttle between sites of energy production (mitochondria) and consumption (cross-bridges and ion pumps). Unexpectedly, isolated fast-twitch skeletal muscle cells of @entity19 @entity2383 (CK-/-) are highly fatigue resistant during stimulation protocols that stress aerobic metabolism. We have now studied different aspects of mitochondrial function in CK-/- skeletal muscle. Intact, single fibres of flexor digitorum brevis (FDB) muscles were fatigued by repeated tetanic stimulation (70 Hz, 350 ms duration, duty cycle 0.14). Under control conditions, CK-/- FDB fibres were more fatigue resistant than wild-type fibres. However, after mitochondrial inhibition with @entity3789 , force declined markedly faster in CK-/- fibres than in wild-type fibres. The rapid force decline in CK-/- fibres was not due to decreased myoplasmic [ @entity141 ] during @entity116 (measured with indo-1), which in these fibres remained virtually constant during fatigue in the presence of @entity3789 . Intact, single fibres of highly oxidative soleus muscles were fatigued by repeated @entity116 (50 Hz, 500 ms duration, duty cycle 0.5). All CK-/- soleus fibres tested (n = 9) produced > 40 % force at the end of the fatiguing stimulation period (500 @entity116 ), whereas force fell to < 40 % before 500 @entity116 in two of three wild-type fibres. Mitochondrial [ @entity141 ] (measured with @entity41178 and confocal microscopy) increased during repeated tetanic stimulation in CK-/- but not in wild-type FDB fibres. In conclusion, mitochondria and energy shuttling operate effectively in CK-/- fibres and this is associated with an increase in mitochondrial [ @entity141 ].

Mitochondrial function in intact skeletal muscle fibres of XXXX kinase deficient @entity19 .

@entity19 :: ('10090', 'Species') :: ['mice'] @entity908 :: ('MESH:D003401', 'Chemical') :: ['Creatine'] @entity3789 :: ('CHEBI:17514', 'Chemical') :: ['cyanide'] @entity41178 :: ('MESH:C068483', 'Chemical') :: ['rhod-2'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity116 :: ('MESH:D013746', 'Disease') :: ['tetani'] @entity2383 :: ('MESH:D028361', 'Disease') :: ['deficient in both cytosolic and mitochondrial CK']
@entity908 :: (MESH:D003401,Chemical) :: ['creatine']
