Ketoconazole,an inhibitor of calcium transport in skeletal muscle sarcoplasmic reticulum

Summary Ketoconazole, an antimycotic agent, inhibits calcium binding and accumulation, and induces calcium release in sarcoplasmic reticulum. The Mg²⁺-ATPase and the (Ca²⁺+Mg²⁺)-ATPase activities are stimulated at low but inhibited at high concentrations of ketoconazole.The author wishes to thank Dr K. S. Cheah for discussion and Mr C. C. Ketteridge for preparing the sarcoplasmic reticulum and carrying out the ATPase assays.     

Diurnal rhythm of active calcium transport in rat intestine

The active calcium transport along the small intestine of adult rat was shown to exhibit daily rhythmic variations of considerable amplitude. Both the light-dark cycle and the time of food presentation acted as synchronizers of the rhythm observed.     

Diurnal rhythm of active calcium transport in rat intestine

Summary The active calcium transport along the small intestine of adult rat was shown to exhibit daily rhythmic variations of considerable amplitude. Both the light-dark cycle and the time of food presentation acted as synchronizers of the rhythm observed.This work has been supported by Polish Academy of Sciences within the project MR II.1.1.6.     

The effect of pyrophosphate and diphosphonates on calcium transport in red cells.

The effect of 0.5 mM pyrophosphate (PPi), disodium ethane-4-hydroxy-1,1-diphosphonate (EHDP) and disodium dichloromethane diphosphonate (Cl2MDP) on the ATP-dependent Ca2+ extrusion from the human red cell ghosts was studied. PPi and Cl2MDP had no effect, when introduced into the cells or added outside to the medium. EHDP slightly increased the calcium concentration in the released cells and slightly decreased the rate constant of the calcium transport, having opposite effects when it was inside or outside the cells. PPi and the 2 diphosphonates were not found to move easily across the red cell membrane.     

Effects of calcium-EGTA buffers on active calcium transport in inside-out red cell membrane vesicles

Summary In inside-out red cell membrane vesicles, the free calcium concentration half-maximally stimulating active calcium uptake is about 2 orders of magnitude smaller in a calcium-EGTA buffer than in media containing unbuffered calcium. In calcium-EGTA buffer, the maximum rate of calcium uptake is determined by the total calcium concentration present. A possible model for explaining these findings is presented.Acknowledgments. This work was supported by the Scientific Research Council, Ministry of Health, Hungary (6-03-0306-01-1/Gá). We thank for the valuable comments of Dr Ilma Szász and for the skilful technical assistance of Mrs M. Sarkadi.     

Effects of calcium-EGTA buffers on active calcium transport in inside-out red cell membrane vesicles.

In inside-out red cell membrane vesicles, the free calcium concentration half-maximally stimulating active calcium uptake is about 2 orders of magnitude smaller in a calcium-EGTA buffer than in media containing unbuffered calcium. In calcium-EGTA buffer, the maximum rate of calcium uptake is determined by the total calcium concentration present. A possible model for explaining these findings is presented.     

Nuclear transport and the mitotic apparatus: an evolving relationship

The trafficking of macromolecules between the cytoplasm and the nucleus is controlled by the nuclear pore complexes (NPCs) and various transport factors that facilitate the movement of cargos through the NPCs and their accumulation in the target compartment. While their functions in transport are well established, an ever-growing number of observations have also linked components of the nuclear transport machinery to processes that control chromosome segregation during mitosis, including spindle assembly, kinetochore function, and the spindle assembly checkpoint. In this review, we will discuss this evolving area of study and emerging hypotheses that propose key roles for components of the nuclear transport apparatus in mitotic progression.     

Inhibition of calcium transport in mitochondria byβ-receptor blocking substances and its reactivation by phospholipids

Zusammenfassung -Rezeptorenblocker hemmen den aktiven Kalziumtransport an isolierten Herzmitochondrien und den phospholipidvermittelten Kalziumtransport in Ausschüttelungsversuchen. Die Hemmung des mitochondrialen Kalziumtransportes lässt sich durch Phosphatidylserin und weniger stark durch Lecithin (10^–4 g/ml) aufheben, während andere Phospholipide und deren Bausteine wirkungslos sind.

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Parts of this study were presented at the Symposium on Calcium and the Heart of the International Study Group for Research in Cardiac Metabolism held at London on the 6th September 1970.     

In vivo inactivation of transglutaminase during the acute acrylamide toxic syndrome in the rat

The activity of liver and brain transglutaminase is rapidly lost following i.p. injection of acrylamide (50-200 mg/kg). Other enzymes investigated were not modified by the treatment, with the exception of brain enolase.     

In vivo inactivation of transglutaminase during the acute acrylamide toxic syndrome in the rat

Summary The activity of liver and brain transglutaminase is rapidly lost following i.p. injection of acrylamide (50–200 mg/kg). Other enzymes investigated were not modified by the treatment, with the exception of brain enolase.     

Tissue distribution and substrate specificity of an epoxide hydrase in the gypsy moth,Lymantria dispar

The stereoselectivity of the enzymatic hydration of disparlure, the pheromone for the gypsy mothLymantria dispar, and for twomeso analogues was determined. A single expoxide hydrase (EH), present in various male and female moth tissues, converted disparlure and the analogues to their respectivethreo-(R,R)-diols with high stereoselectivity as determined by analysis of the diols by chiral phase capillary gas chromatography. This EH recognizes thecis-nature of the dialkyl oxirane, but shows poor discrimination of the two alkyl chains.     

The effect of vitamin D3 and 25-hydroxycholecalciferol on intestinal transport of calcium in vivo and in vitro

Zusammenfassung 8 Stunden nach Injektion von 25-Hydroxycholecalciferol bei rachitischen Ratten steigerte sich der Kalzium-Transport des Duodenum in vivo wie auch in vitro bedeutend. Während dieser Zeit war Vitamin D₃, wirkungslos. 24 h nach der Injektion stimulierten beide Verbindungen in ähnlichem Masse den Kalzium-Transport.