Kinetics of ATP hydrolysis and tension production in skinned cardiac muscle of the guinea pig

摘要: Abstract The kinetics of ATP hydrolysis and tension responses were studied simultaneously in a permeabilized preparation cardiac tissue the guinea pig. This was achieved by combining laserflash photolysis P3-1-(2-nitrophenyl)ethyladenosine 5'-triphosphate ("caged-ATP") rapid freezing technique. In presence calcium ions, increased following photolytic production with half-time 0.3 s. timecourse consisted an initial phase followed steady-state rate 0.4 s-1, indicating that rate-limiting step ATPase isometric fibers is slower subsequent to nucleotide step: steady state intermediate probably actomyosin-ADP complex. absence rigor decreased upon 0.45 time course biphasic hydrolysis, which too slow measure over scale these experiments (less than 0.04 s-1). A comparison results obtained this study those reported for rabbit skeletal muscle reveals qualitative similarities between also quantitative differences their physiological kinetic behavior.