Laser diffraction and speckling studies in skeletal and heart muscle.

The optical setup including a low power helium-neon laser as well as microcomputer system based U 880 for on line investigation of laser diffraction and scattering in skeletal and heart muscle is described. Frog muscle single fibres yield excellent laser diffraction patterns which are best adapted to measurements of the sarcomere dynamics. In the presence of 6 mM caffeine the diffraction disappears gradually and a moving speckle pattern occurs. Diffraction and speckle phenomena are compared of skeletal and heart muscle preparations. From autocorrelation and Fourier transformation of intensity fluctuations ("speckling") in resting mammalian cardiac muscle tissue results a favoured frequency of 1 Hz. It is supposed that clusters of sarcomeres move rhythmically but independent from each other as long as the preparation is not stimulated repetitively.