[Interaction of vanadate with the contractile system of striated muscles in the presence of natural analogs of ATP and ADP].

Vanadate produced dissociation of rigor-activated (calcium-free) fibres or rabbit m. psoas muscle in the presence of the studied various natural analogs of ATP (NTP) at optimal concentrations. By the degree of sensitivity to vanadate it is possible to establish the order ATP approximately greater than CTP greater than UTP greater than ITP greater than GTP.

[Reduced sensitivity of glycerinated rabbit m.psoas fibers to diprotonated vanadate during decrease in pH].

Vanadate (Na3VO4) action of the isometric force of maximal Ca2(+)-activated fibre has been studied at pH from 6.3 to 7.3.

[The effect of pyrophosphate on the rigor fibers of rabbit m. psoas fibers].

The effect of MgPPi on the rigor force of glycerinated fibres in the range of ionic strength 75-250 mM at two temperatures 18 degrees and 5 degrees C was studied. At 18 degrees C the maximum of this effect was above the range of average ionic strength. At 5 degrees C the greatest effect of MgPPi was observed at low ionic strength.

[Mechano-chemical properties of actomyosin-ADP complexes in rabbit psoas muscle fibers].

The relaxing effect of vanadate on active contractile system is found to be completely absent from rigor skinned fibres with ADP even on their stretching up to the forces comparable with the active ones, though vanadate is likely to bind not very firmly with crossbridges not containing inorganic phosphate. Probable reasons of such distinction are considered. The complex actomyosin-ADP in the rigor fibres is supposed to have significantly lower free energy independently of its deformation than the one of the same composition in the active ones.

[Changes in the force-pCa characteristics of the striated muscles of the skate after treatment with phalloidin].

The pCa/tension relationship of glycerinated skate thoracic fin muscle was found to fit well in the Hill equation. Phalloidin has been shown to decrease calcium sensitivity (shift of pK to the lower pCa by 0.27 +/- 0.