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Biomedical subjects

M Kordas

Publications and source records attributed to M Kordas.

26 records · Page 2Linked to original sources
PubMed1972

An attempt at an analysis of the factors determining the time course of the end-plate current. I. The effects of prostigmine and of the ratio of Mg 2+ to Ca 2+ .

1. An attempt was made to analyse the factors which might determine the time course of the falling phase of the end-plate current.2. The end-plate current was measured by ;clamping' the membrane potential during neuromuscular transmission.3. The falling phase of the end-plate current was found to consist of a non-exponential, and an exponential portion, the duration of both of which varies under different experimental conditions.4. The results suggest that the rate constants determining the dissociation of the receptor-mediator complex seem greatly to influence the time course of the end-plate current.

Animals↗
PubMed1972

An attempt at an analysis of the factors determining the time course of the end-plate current. II. Temperature.

1. An attempt was made to analyse further the factors which might determine the time course of the falling phase of the end-plate current.2. The end-plate current was measured by ;clamping' the membrane potential during neuromuscular transmission. The falling phase of the end-plate current had an exponential and a non-exponential portion.3. The exponential portion of the falling phase of the end-plate current was found to be strongly affected by changes in the membrane potential and by relatively small changes in temperature.4. It is suggested that the two rate constants which determine the dissociation of the receptor-mediator complex are affected by both temperature and the membrane potential. Under certain experimental conditions these two rate constants alone seem to determine the time course of the exponential portion of the falling phase of the end-plate current.

Animals↗
PubMed1970

The effect of procaine on neuromuscular transmission.

1. The mechanism of procaine action on post-synaptic receptors for acetylcholine was studied by recording the end-plate current at membrane potentials ranging from about +30 to about -140 mV.2. It has been found that at resting membrane potential of about -60 to -80 mV the end-plate current has a fast initial and a slow late component. During hyperpolarization of the muscle fibre the amplitude of the slow component is depressed and its half-time lengthened. When the membrane potential is inverted the difference in the time course of both components is much less pronounced or absent.3. It is suggested that procaine modifies the receptor response induced by acetylcholine, and that this modification is dependent on membrane potential.

Acetylcholine↗
PubMed1969

The effect of membrane polarization on the time course of the end-plate current in frog sartorius muscle.

1. Intracellular recordings of the end-plate current at different membrane potentials were made, using a voltage-clamp technique.2. When the membrane potential is varied between about +40 and -120 mV, the half-decline time of the end-plate current increases from about 0.6 msec to about 1.6 msec.3. It is suggested that the stability of receptor-mediator complex is affected by the membrane potential.

Animals↗
PubMed1968

A study of the end-plate potential in sodium deficient solution.

1. The effect of anticholinesterases in lengthening the end-plate potential is much more pronounced in a low-sodium solution than in an ordinary Ringer-curare solution.2. To investigate this difference, intracellular recordings of end-plate potentials and of end-plate currents in voltage-clamped muscle fibres were used.3. It was found that the very large lengthening of the end-plate potential in a low-sodium solution was due to a combination of three factors: (i) lengthening of the underlying end-plate current, (ii) an increased membrane resistance and (iii) marked inward-going (anomalous) rectification of the muscle membrane.

Animals↗