[An experimental verification of the histomechanical theory of the working hyperemia of the skeletal muscles: biomicroscopic research].

The histomechanical hypothesis of working hyperemia in skeletal muscle was verified by comparison of the dynamics and values of frog submaxillary muscle arterioles dilation under: 1) 4-Hz twitch contraction and 2) imitation of mechanical component of the twitch contractions. Deformation of arterioles occurred during incomplete tetanus with the maximal effect at the peaks of twitches. The repetitive displacements of a small bunch of muscle fibers with the frequency of 4 Hz and the amplitude of 0.05 to 0.25 mm caused a dilation of the arterioles attached to the fibers. The outer diameter of the arterioles might increase up to 2.2-2.3-fold, i.e. in the same range as under twitch contractions. The data showed the similarity in latency values, in the dynamics of arteriole dilation, and the dependency of the latter on the phase of the spontaneous vasomotion preceding the compared stimuli. These findings suggest that arteriolar dilation is determined by mechanically induced inactivation of pace-makers of these vessels both during passive deformations and under twitch contractions.