Phosphate exchange between high-energy phosphate compounds in resting crustacean muscle

Single giant muscle fibres from Megabalamus psittacus was microinjected with ATP-32P or internally perfused with a solution containing 32P-PArg in an attempt to demonstrate, in the absence of inhibitiors, ATP utilization during mechanical activity with negative results. The rate constant of transfer of 32P from microinjected 32P-PArg to endogenous ATP was studied at two different temperatures, obtaining a Q10 of 1.08 +/- .012. It is concluded that the rate limiting step in the process of transference of phosphate in the resting muscle from balanus is the intracellular diffusion of PArg and not the rate at which the equivalent of Lohman's reaction in invertebrates proceeds.