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Biomedical subjects

S HAGIWARA

Publications and source records attributed to S HAGIWARA.

At least 37 records · Page 2Linked to original sources
PubMed1959

Potassium ions and the inhibitory process in the crayfish stretch receptor.

The effect of the absence of potassium in the bathing solution on the synaptic inhibitory potentials of the crayfish stretch receptor has been studied. The inhibitory potentials were increased in size, i.e. became more hyperpolarizing, in the absence of potassium. Since the resting potential of the cell is increased in the absence of potassium, the alteration of the inhibitory potentials implies that the potassium conductance of the membrane is increased. While other ions, e.g. Cl(-), may also be involved, it seems that the membrane potential during inhibition is mainly dominated by K(+).

Animals↗
PubMed1958

Synaptic potential in the motor giant axon of the crayfish.

Some electrical properties of the synapses between central giant axons (presynaptic) and the motor giant axon (postsynaptic) of the crayfish abdominal nerve cord have been investigated. Postsynaptic potential change in response to presynaptic volleys contains two components: a spike potential and a synaptic potential of very long time course. Amplitude of the synaptic potential is graded according to the number of active presynaptic axons. Conductance increase in the synaptic membrane endures over most of the period of potential change, and it is this rather than the "electrical time constant" of the membrane that in large measure determines the form of the synaptic potential. Temporal summation of synaptic potential occurs during repetitive presynaptic stimulation, and after such stimulation the rate of decay of synaptic potential is greatly slowed.

Action Potentials↗
PubMed1957

Intracellular recording from the giant synapse of the squid.

1. Recording with glass micropipette electrodes inserted close to the synaptic region, in the presynaptic and in the postsynaptic fibers of the giant synapse in the stellate ganglion of the squid, has been accomplished. 2. The forms of the spike and of the synaptic potential are very much like those reported earlier (Bullock, 1948) from macroelectrodes. The crest time and the rate of fall are labile and depend on the state of fatigue, though the time of initiation of the postsynaptic potential does not. 3. It is concluded after examination of both intra- and extracellular recordings that there is a real synaptic delay of the order of 1 or 2 milliseconds at 15-20 degrees C. 4. There is sometimes a very small and sometimes no visible deflection in the intracellular postsynaptic record attributable to the presynaptic spike. It is concluded that transmission cannot be electrical. 5. The amplitude of the postsynaptic potential can be controlled over some range by the amplitude of the presynaptic potential. 6. Hyperpolarization of the postsynaptic membrane results in increase in amplitude of spikes up to 200 millivolts, in increase in the membrane potential level at which the spike flares up, but in no considerable change in the amplitude in postsynaptic potential. 7. The postsynaptic potential can add to the late falling phase and the undershoot of an antidromic spike in the postfiber but cannot add to the crest or early part of the falling phase. The earliest part of the antidromic spike during which the postsynaptic potential can add is probably a period of refractoriness to electrical shock by analogy with the properties of the axon.

Animals↗