[Permeability of sarcoplasma reticulum membrane for monovalent cations].

Potassium, sodium and Tris ion permeability of sarcoplasmic reticulum (SR) vesicles was investigated by the method of potential-sensitive probes. Membrane potentials were generated by changing the ionic environment of vesicles and were measured using the probe 3,3'-dipropyl-2,2'-thiodicarbocyanine (diS-C3-(5)). It was shown that 2/3 of the vesicles (Type I) were permeable to K+ and Na+ while the remaining 1/3 (Type II) were not.

[Study of sarcoplasmic reticulum membrane permeability using potential-sensitive fluorescent probes].

A new method is proposed for quantitative studies of SR membrane permeability. It involves measuring to diffusion potentials, arising at salt concentration gradient on the SR membrane due to its anion and cation permeability differences. Visualization of processes of negative chloride potential arising in adding MeCl2 and its further dissipation was realized with diS-C3-(5).

[Transmembrane potential formation upon ATP hydrolysis in sarcoplasmic reticulum].

Fluorescent cyanine (diS-C3-(5), diS-C2-(5), diO-C3-(5)) and oxonol (diBA-C4-(5)) potential-dependent dyes appeared to be extremely effective in detecting and studying the potential formed on the fragmented sarcoplasmic reticulum membrane under Ca2+ transport When [Ca2+] less than 5 X 10(-7) M ATP hydrolysis leads to formation of transmembrane potential (positive inside vesicules) caused by the Ca-independent ATPase activity. The potential is formed by a monovalent ion, presumably by H+, and possibly by Mg2+ ions. Ca-dependent ATPase activation by Ca2+ makes the potential to drop sharply and successive Ca2+ transport proceeds at low potential value.

[Study of the transmembrane potential of mitochondria using cyanine dyes].

Changes in fluorescent intensity of cyanine dyes dis-C3-(5) and dis-C2-(5) were measured in suspension of rat liver mitochondria upon the development of the energized state by adding succinate or ATP. It has been shown that these dyes possess a rotenone-like effect but they do not damage the inner mitochondrial membrane. The data on ATP synthesis and Ca2+ transport correspond to the basic aspects of the chemiosmotic conception.