Relaxation of muscle fibres by photolysis of caged ATP.

A novel method has been developed for studying the reaction kinetics of the force-generating mechanism in muscle. Inert photolabile precursors of ATP or ADP are incorporated into muscle fibres having their surface membrane barrier removed. The nucleotide is then rapidly liberated by laser pulse photolysis. This circumvents the limitation in time resolution set by diffusion of nucleotide from the medium bathing the fibre. This laser photolysis method may be applicable to studies of the dynamic properties of many biological systems.