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E Suematsu

Publications and source records attributed to E Suematsu.

24 records · Page 2Linked to original sources
PubMed1984

Inositol 1,4,5-trisphosphate releases Ca2+ from intracellular store sites in skinned single cells of porcine coronary artery.

Effects of inositol 1,4,5- trisphosphate , extracted from human erythrocyte ghosts, on Ca2+ release from intracellular store sites were studied in saponin-treated single muscle cells of the porcine coronary artery. Application of micromolar concentrations of inositol 1,4,5- trisphosphate released Ca2+ from the intracellular non-mitochondrial store sites, within 1 min. However, when the concentrations of free Ca2+ were over 1.5 X 10(-6) M, the release of Ca2+ by this agent was inhibited. The Ca2+ releasing mechanism differed from that seen with A23187, therefore this release of Ca2+ from store sites was not due to Ca2+ ionophore actions. This agent may play the role of messenger in increasing the cytosolic Ca2+, provoking pharmaco-mechanical coupling, and thus producing the contraction.

Animals↗
PubMed1983

Stimulation of Ca2+ efflux by N-formyl chemotactic peptides in guinea-pig peritoneal macrophages.

Effects of N-formyl chemotactic peptides on the Ca2+ influx and efflux were investigated in guinea-pig peritoneal macrophages using an isotope tracer. fMet-Leu-Phe did not enhance the influx of 45Ca2+ into macrophages, whereas it stimulated the efflux of 45Ca2+ from macrophages at concentrations ranging from 10(-10) M to 10(-7) M. fMet-Met-Met and fMet-Leu also stimulated the 45Ca2+ efflux, albeit at much higher concentrations, while there was no stimulation with fMet. The mitochondrial inhibitors, oligomycin and NaN3, did not modify the 45Ca2+ efflux induced by the chemoattractants, yet they did induce the release of 45Ca2+ from the mitochondria. On the other hand, higher concentrations of the calmodulin antagonists, chlorpromazine and trifluoperazine, induced the release of 45Ca2+ from the NaN3-insensitive Ca2+ store site and mimicked the enhancement of the 45Ca2+ efflux by N-formyl chemotactic peptides. Thus, N-formyl chemotactic peptides appear to increase the levels of intracellular free Ca2+ in guinea-pig peritoneal macrophages, probably by inducing the release of Ca2+ from the NaN3-insensitive Ca2+ store site.

Animals↗
PubMed1983

Ca2+ release in the endoplasmic reticulum of guinea pig peritoneal macrophages.

Passive permeability of the endoplasmic reticulum of saponin-treated macrophages to Ca2+ was studied by the filtration method using 45Ca. The Ca2+ release from the endoplasmic reticulum of macrophages was enhanced by the presence of submicromolar concentrations of Ca2+ in the medium. The Ca2+ release was enhanced by caffeine, and suppressed by MgCl2. These phenomena are similar to the Ca2+-induced Ca2+ release reported for the sarcoplasmic reticulum of skeletal muscle. On the other hand, adenine suppressed the Ca2+ release from the endoplasmic reticulum, while it reportedly enhanced the Ca2+-induced Ca2+ release of the skeletal muscle. The threshold concentration of Ca2+ for the Ca2+-induced Ca2+ release was approximately 10(-8) M in the presence of 0.95 mM MgCl2 in macrophages. The spontaneous spreading of macrophages and spontaneous migration of macrophages were inhibited by adenine, and also by caffeine in spite of the enhancement of the Ca2+-induced Ca2+ release.

Animals↗