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Biomedical subjects

T Shiga

Publications and source records attributed to T Shiga.

At least 253 records · Page 14Linked to original sources
PubMed1977

Spin label studies on the human erythrocyte membrane. Two sites and two phases for fatty acid spin labels.

Human erythrocytes, untreated and glutaraldehyde-treated, were spin labeled with three kinds of fatty acid labels, and their electron spin resonance (ESR) spectra were studied in detail at various temperatures. 1. The better spectral resolution could be obtained by packing the erythrocytes in a hematocrit capillary tube, because of the preferential parallel orientation of the cylindrical axes of erythrocyte-disc to the centrifugal axis. 2. It was demonstrated by the incorporation and the release of the labels that the membrane possessed two kinds of the fatty acid "sites": the tightly and weakly binding "sites" at the approximate molar ratio of 1:1. The rough estimates of the binding constants were obtained, which reproducibly varied with the blood donors over a period of a year. 3. The temperature dependency of the ESR spectra revealed the presence of two distinct phases, perhaps the solid and fluid phases. With lowering of the temperature, the fluid phase became more solid but the solid phase unchanged. The pretreatment of the erythrocytes with glutaraldehyde increased the amount of the frozen phase, corresponding to the decrease of the membrane flexibility.

Albumins↗
PubMed1977

Effect of nitric oxide on the oxygen transport of human erythrocytes.

The oxygen dissociation curve of partially NO-liganded hemoglobin of human erythrocytes is measured. As the percentage of NO ligation increases, the affinity of nonliganded hemoglobin for oxygen increases and the heme-heme interaction decreases; furthermore, methemoglobin is formed. Therefore, NO affects the oxygen transport function of hemoglobin, decreasing the oxygen supply to peripheral tissues, because of (1) simple diminution of the available hemoglobin by the tightly bound NO, (2) the high affinity of hemoglobin for oxygen, and (3) the inevitable formation of methemoglobin.

Erythrocytes↗
PubMed1976

Effect of pyridoxal 5'-phosphate on the oxygen affinity of human erythrocytes.

Pyridoxal 5'-phosphate (PLP), an allosteric effector for the oxygenation of haemoglobin, was incorporated readily into erythrocytes and disappeared from them by simple passive diffusion. The disappearance of PLP from the cells was accelerated by the generation of 2,3-DPG in a medium of inosine, pyruvate and phosphate. The oxygen dissociation curve measured at an extracellular pH of 7.4 demonstrated that PLP incorporated into the cells also lowered the oxygen affinity and that PLP functionally compensated for a metabolically reduced 2,3-DPG. However, the dependency of the oxygen affinity on the intracellular PLP concentration showed a different pattern from the observed for 2,3-DPG. On the other hand, the lowering of intracellular pH by organic phosphates accumulated in the cells was much larger with PLP than with 2,3-DPG. The peculiar relationship between the oxygen affinity of erythrocytes and the intracellular PLP concentration is discussed in detail. The present study may offer a new prospect for the preservation of blood with a normal function.

Erythrocytes↗