Application of pulsed-gradient 31P NMR on frog muscle to measure the diffusion rates of phosphorus compounds in cells.

Pulsed-gradient 31P NMR was used to measure the diffusion rates of phosphorus compounds in aqueous solution and in living muscles. The diffusion rates of creatine phosphate and inorganic phosphate in intact frog muscle cells were reduced by a factor of approximately 2 from those in aqueous solution, which suggests that the apparent intracellular viscosity is approximately 2 times larger than in aqueous solution.