Optical density changes of single muscle fibers in sodium-free solutions

Abstract

MGLAUGHLIN, S. 6. A., AND HINKE, J. A. M. 1968. optical density changes of single muscle fibers in sodium-free solutions. Can. J. Physiol. Pharrnacol. 46,[247][248][249][250][251][252][253][254][255][256][257][258][259][260] The optical density, O.B., s f single striated muscle fibers frsm the giant barnacle, Balanus izubikl~, was measured at 50-mp intervals between 450 and 850mp. At all wavelengths, the O.D. decreased markedly when the normal Ringer bathing solution was replaced by sodium-free sucrose Ringer solution. For example, at 850 my the O.D. of the fibers, relative to the initial value in normal Ringer solution, decreased from 1 to 0.21 LO.06 in 25 min. The corresponding increase in the transmittance, T, (O.D.--log T ) was from 5 "/, to 55 %. This change in O.D. could be wersed by returning the normal Ringer bathing solution to the bath. Large, reversiblc decreases in O.D. were also observed when potassium and Tris were used as substitutes for sodium. These changes in 0. D. are explained by the theory of light scattering if it is assumed that sodium is bound to rnacromolxules in the myoplasrn. This assumption is supported by experiments with cation-sensitive microelectrodes, which indicate that most of the sodium in the muscle fibers is not free in the myoplasm. When the fibers were bathed in sodium-free, lithiumsubstituted Ringer solution, a small reversible increase in the 0.D. was observed, which may indicate that lithium is complexed more strongly than sodium by macromolecules in the myoplasm. This conclusion is compatible with the known affinities of carboxylate ion exchange resins for the alkali metal cations.

Intracellular pH of single crustacean muscle fibres by the DMO and electrode methods during acid and alkaline conditions.

“…A damaged fibre reveals itself by a localized opacity in the myoplasm, by a 'kink' which remains even after stretching, by localized changes in diameter or by localized contractures. The impaled fibres, judged to be damage-free after prolonged equilibration, showed resting potentials and electrolyte composition comparable to those reported by others (Hagiwara, Chicibu & Naka, 1964;Beauge & Sjodin, 1967;Brinley, 1968;McLaughlin & Hinke, 1968;Gayton, Allen & Hinke, 1969). Fig.…”

“…In the former category, the weak acid, 5,5-dimethyloxazolidine-2,4-dione (DMO), is now most frequently used. Use of the pH micro-electrode is probably the method of choice but only a few laboratories have made use of it (Caldwell, 1954(Caldwell, , 1958Kostyuk & Sorokina, 1961;Carter, Rector, Campion & Seldin, 1967; McLaughlin & Hinke, 1968;Paillard, 1972;Thomas 1974;Aickin & Thomas, 1975) mainly because of the technical difficulty in constructing such electrodes with small enough tips for most cellular systems.…”

The activities and concentrations of sodium and potassium in toad oocytes

“…Cope found that the NMR spectrum of sodium in muscle was greatly broadened, and Robertson observed that although most of the potassium could be extruded from a muscle by subjecting it to pressure, only about 18% of the sodium could be extruded in this manner. Evidence from denaturation (Hinke & McLaughlin, 1967) and light scattering (McLaughlin & Hinke, 1968) experiments also suggests that some sodium is bound to myosin in living muscle fibres, but the location of most of the sequestered sodium in muscle is at present unknown. In squid giant axons measurements of the aNa/CNa ratio (Hinke, 1961) indicate that about 25 % of the sodium in this cell is sequestered.…”

Distribution and State of Monovalent Ions in Skeletal Muscle Based on Ion Electrode, Isotope, and Diffusion Analyses*

“…The fiber-filled capillary was then mounted between two solutions PH FIGURE 9. A fresh fiber was pulled into the lumen of a glass capillary, and after 20 hours of equilibration the two ends of the fiber were cut cleanly at the ends of the capillary.…”