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Biomedical subjects

L Goldman

Publications and source records attributed to L Goldman.

At least 505 records · Page 28Linked to original sources
PubMed1972

Inactivation of the sodium current in Myxicola giant axons. Evidence for coupling to the activation process.

Experiments were conducted on Myxicola giant axons to determine if the sodium activation and inactivation processes are coupled or independent. The main experimental approach was to examine the effects of changing test pulses on steady-state inactivation curves. Arguments were presented to show that in the presence of a residual uncompensated series resistance the interpretation of the results depends critically on the manner of conducting the experiment. Analytical and numerical calculations were presented to show that as long as test pulses are confined to an approximately linear negative conductance region of the sodium current-voltage characteristic, unambiguous interpretations can be made. When examined in the manner of Hodgkin and Huxley, inactivation in Myxicola is quantitatively similar to that described by the h variable in squid axons. However, when test pulses were increased along the linear negative region of the sodium current-voltage characteristic, steady-state inactivation curves translate to the right along the voltage axis. The shift in the inactivation curve is a linear function of the ratio of the sodium, conductance of the test pulses, showing a 5.8 mv shift for a twofold increase in conductance. An independent line of evidence indicated that the early rate of development of inactivation is a function of the rise of the sodium conductance.

Animals↗
PubMed1971

Rectification in instantaneous potassium current-voltage relations in Myxicola giant axons.

1. Measurements of the instantaneous K current, under voltage clamp, were obtained using paired de- and hyperpolarizing clamp pulse sequences. The instantaneous potassium current-voltage relations so obtained showed constant field type rectification.2. The zero current potential of the instantaneous K current-voltage relation, when examined as a function of the K concentration, [K](o), behaved like a Nernst concentration cell potential for K. It was concluded that during the generation of the delayed current, the membrane shows substantial selectivity for K.3. The equivalent of the ;Frankenhaeuser-Hodgkin space' in Myxicola was found to be more difficult to load with K ions than in squid. The thickness of the space may be taken as effectively about seven times larger than in squid.4. Myxicola axons were found to show little or no long time constant delayed current inactivation as has been described for squid.5. In high [K](o) a negative steady-state conductance was observed which was predictable from the independence principle with a suitable scaling factor.

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