Showing papers in "Journal of Physiological Sciences in 1982"

Pancreatic A cell generates action potential.

Abstract: Intracellular membrane potential recording was attempted with pancreatic endocrine cells in monolayer culture. Morphologically identified A cells produced spike action potentials in response to injected electric current. The action potential was also evoked in the sodiumfree medium. It was concluded that pancreatic A cells are electrically excitable and probably generate Ca spike.

Rapid pressure changes and surface displacements in the squid giant axon associated with production of action potentials.

Abstract: By using both optical and mechano-electric detectors, we have shown that the squid giant axon swells when an action potential is generated. The maximum swelling is reached at the peak of the action potential. The undershoot of the membrane potential is associated with a marked shrinkage of the axon. We have also demonstrated these mechanical changes in axons from which a major portion of the axoplasm has been removed. We have examined the effects of changing the tonicity of the external medium and of applying several chemical reagents.

Coil planet centrifugal and capillary tube centrifugal analysis of factors regulating erythrocyte osmotic fragility and deformability.

Abstract: Hydrated and dehydrated red cell samples were prepared from normal human red cells using the antibiotic nystatin. Furthermore, a series of red cell samples exposed to elevated temperature (20-50°C, 10 min) were prepared. The osmotic fragility and deformability of these red cells were then measured, using the coil planet centrifuge system and the capillary tube centrifugal technique, respectively. The osmotic fragility of nystatin-treated red cells decreased and the deformability increased as dehydration of red cells progressed and alternatively, hydrated cells showed increased osmotic fragility and reduced deformability. Red cells exposed to elevated temperatures up to 49°C for 10 min had no changes in mean corpuscular volume or in red cell shape. Above 47°C, however, spectrin extractability progressively decreased and osmotic fragility and deformability decreased. Results suggest that the osmotic fragility and deformability of red cells are interrelated, and are controlled by the geometry of the cell, including the ratio of cell surface area to cell volume and the viscoelastic properties of the membrane.