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S H Bryant

Publications and source records attributed to S H Bryant.

98 records · Page 6Linked to original sources
PubMed1969

Cable properties of external intercostal muscle fibres from myotonic and nonmyotonic goats.

1. In preparations of about 200 fibres each from thirty-nine biopsies of external intercostal muscle taken from nine myotonic and six nonmyotonic goats, cable properties were determined at 38 degrees C for individual fibres with a pair of intracellular micro-electrodes.2. In each preparation the mean fibre dimensions, determined histologically and corrected for shrinkage, were used to calculate the mean membrane resistance, R(m), fibre capacitance, C(t), and myoplasmic resistivity, R(i). In the 124 nonmyotonic fibres the mean values were: R(m), 1897 Omega.cm(2), C(t), 4.1 muF/cm(2), and R(i), 112 Omega.cm. In 151 myotonic fibres R(m) was 5589 Omega.cm(2), C(t), 4.4 muF/cm(2), and R(i), 103 Omega.cm.3. Conductance of the fibre core times unit length increased with cross-sectional area, and fibre capacitance per unit length increased with perimeter. There was little correlation of membrane resistance per unit length of fibre with either fibre perimeter or resting potential.4. The principal abnormality of cable properties in the myotonic fibre is its threefold higher membrane resistance, which accounts for its decreased electrical current rheobase.

Animals↗
PubMed1966

Sodium, potassium, and chloride fluxes in intercostal muscle from normal goats and goats with hereditary myotonia.

IN ISOLATED BUNDLES OF EXTERNAL INTERCOSTAL MUSCLE FROM NORMAL GOATS AND GOATS WITH HEREDITARY MYOTONIA THE FOLLOWING WERE DETERMINED: concentrations and unidirectional fluxes of Na(+), K(+), and Cl(-), extracellular volume, water content, fiber geometry, and core-conductor constants. No significant difference between the two groups of preparations was found with respect to distribution of fiber size, intracellular concentrations of Na(+) or Cl(-), fiber water, resting membrane potential, or overshoot of action potential. The intracellular Cl(-) concentration in both groups of preparations was 4 to 7 times that expected if Cl(-) were distributed passively between intracellular and extracellular water. The membrane permeability to K (P(K)) calculated from efflux data was (a) at 38 degrees C, 0.365 x 10(-6) cm sec(-1) for normal and 0.492 x 10(-6) for myotonic muscle, and (b) at 25 degrees C, 0.219 x 10(-6) for normal and 0.199 x 10(-6) for myotonic muscle. From Cl(-) washout curves of normal muscle usually only three exponential functions could be extracted, but in every experiment with myotonic muscle there was an additional, intermediate component. From these data PP(cl) could be calculated; it was 0.413 x 10(-6) cm sec(-1) for myotonic fibers and was 0.815 x 10(-6) cm sec(-1) for normal fibers. The resting membrane resistance of myotonic fibers was 4 to 6 times greater than that of normal fibers.

Animals↗