[Biochemical characteristics of a muscle perfusate and its effects on mediator release in the neuromuscular synapse].

Histidine-containing compounds (HCC) were found, using diazoreaction and reaction with diethylpyrocarbonate, a specific histidine reagent, in the perfusate of the frog hindlimb vasculature. After gel filtration on sephadex G-25 about 80% of HCC were eluted with a fraction with molecular mass less than 5000 kD. The studies of the perfusate influence on the characteristics of quantum secretion of transmitter in the preparation of frog cutaneopectoral muscle have shown that the perfusate increased the quantum content of end-plate potentials (EPP) due to increasing binominal parameter and decreasing frequency of miniature EPP.

[Sodium and potassium content of intrafusal muscle fibers and their resting membrane potential in different ionic media].

X-ray microanalysis revealed a high sodium concentration in intrafusal fibers of the frog-muscle whereas it appeared to be normal in extrafusal ones. Potassium concentration was practically the same both in intra- and extrafusal fibers which is in good agreement with the data obtained earlier with other techniques. Electrophysiological experiments demonstrated a similar behaviour of the resting MP found in both kinds of fibers in solutions with different ionic composition.

[Synaptic structures of the intra- and extrafusal muscle fibers of the frog].

The direct-coloring thiocholine technique used for determining cholinesterase in intra- and extrafusal muscle fibers disclosed the presence of two kinds of nerve endings (twitch and grape types) in these fibers. Moreover, it was found that the spindle has fibers combining both types of innervation. The histochemical data were in good agreement with the previously reported electrophysiology findings.