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Biomedical subjects

A Ishida

Publications and source records attributed to A Ishida.

At least 343 records · Page 19Linked to original sources
PubMed1979

Intracellular distribution of calcium in cardiac muscles studied by electron microscope autoradiography.

The intracellular distribution of calcium was investigated by 45Ca electron microscope autoradiography in the frog or rat ventricular muscle and guinea pig papillary muscle. The muscle was incubated for 30 min in 45Ca-Ringer's solution or high Ca solution in which 1/10--1/20 of Ca was replaced with 45Ca. The distribution of developed silver grains sensitized by the 45Ca (45Ca grains) was found to be 38% in the mitochondria, 43% in the myofibrils and 19% in the other regions (8% in the cytoplasma and 11% in the various membranous structures) in the frog muscle cell incubated in the 45Ca-Ringer's solution. After electrical stimulation (10 Hz, 5 min), the distribution was 22% in the mitochondria, 53% in the myofibrils and 25% in other regions. Similar results were obtained after high K stimulation in the frog ventricular muscles and after electrical stimulation in high Ca solution in guinea pig papillary muscles. Following the addition of 1 X 10(-6) g/ml adrenaline into the incubating solution, the grain distribution in guinea pig papillary muscles did not show significant change but the distribution in myofibril decreased after electrical stimulation, while it increased in the mitochondria. Longitudinal localization of 45Ca grains along the myofibril was also examined and it was a general tendency throughout all animals examined that the grain density at the A band and near the Z band decreased after electrical stimulation, while it increased at the I band and, especially, at the A-I junction.

Animals↗
PubMed1978

Binding of 45Ca to intercalated discs of cardiac muscles studied by electron microscope autoradiography.

The binding sites of Ca2+ entering the injured cardiac muscle cell was investigated by 45Ca electron microscope autoradiography in guinea pig papillary muscle and in frog ventricular muscle. The muscle was injured in Ca-free Tyrode's solution, transfered into 45Ca-Tyrode's solution and, after 30 min, fixed and cut into thin sections. An autoradiogram was taken after exposure (4--7 weeks) the thin film of the section was developed. Fine, or sometimes filamentous, silver grains produced by radiation with 45Ca were frequently observed on the intercalated discs of injured cells where most of the nexal membranes were separated. The number of 45Ca grains on the discs of injured cells was eight times more than that found on intact cells. The concentration of 45Ca grains estimated by the number of grains per unit area was 3.2 times higher in the disc region than that in the other cytoplasmic regions in the injured cells, while in the intact cells it was only 1/3 of that found in the latter. The localization of 45Ca grains along the disc of the injured cell was also examined and the fine grains were seen to be located on the separated nexal membrane or at the cytoplasmic side of the desmosome and fascia adherens. It is likely that Ca2+ binds with the nexal membrane and the resulting structural change, such as nexal separation, is indispensable for intercellular uncoupling or healing-over of cardiac muscles.

Animals↗
PubMed1977

A carbon monoxide-binding hemoprotein formed by heme accumulation in Escherichia coli.

A CO-binding hemochrome was accumulated in Escherichia coli cells, when intracellular heme concentration was increased by aerobic incubation of resting cell suspensions with ALA. Reduced minus oxidized difference spectrum of the hemochrome showed peaks at 560, 530, and 430 nm and a shoulder at 575 nm. The peaks of CO reduced minus reduced difference spectrum were located at 572, 540, and 422 nm. The CO spectrum was similar to but not identical with the spectrum of cytochrome o, a known terminal oxidase in E. coli. SDS-polyacrylamide gel electrophoresis of the CO-binding hemochrome showed its molecular weight to be about 33,000. The hemochrome in crude cell-free extracts was oxidized by aeration and reduced by the addition of succinate or NADH. The reduction by succinate was inhibited by inhibitors of succinate dehydrogenase [EC 1.3.99.1], and the reduction by NADH was inhibited by 2-heptyl-4-hydroxy-quinolin-N-oxide, which is an inhibitor of electron transport in E. coli cells.

Aerobiosis↗