Direct addition of insulin inhibits a high affinity Ca2+-ATPase in isolated adipocyte plasma membranes.

The mechanism by which insulin regulates cellular metabolism remains unknown although indirect evidence suggests that alterations in intracellular calcium are important. More specifically, it has been proposed that insulin triggers an increase in intracellular calcium which is responsible for the subsequent modification of metabolic activities. The cell maintains a large electrochemical gradient for ionised calcium between the cytoplasm (less than 10(-6) M, as determined for muscle and nerve) and the extracellular environment (less than 10(-3) M). The plasma membrane may, therefore, be important in the regulation of calcium homeostasis, as a slight alteration in the processes maintaining this gradient could result in marked changes in cytoplasmic calcium. One such process is the active extrusion of calcium from the cell by a high affinity calcium-stimulated ATPase (Ca2+-ATPase). Such a mechanism has been well established in red cells and is postulated in nerve, liver and muscle. We have identified a high affinity Ca2+-ATPase in a plasma membrane-enriched subcellular fraction isolated from rat adipocytes which may provide the enzymatic basis for a calcium extrusion pump. We demonstrate here that the Ca2+-ATPase is specifically inhibited by the direct addition of physiological concentrations of insulin to the direct addition of physiological concentrations of insulin to the isolated plasma membranes. This effect suggests that direct regulation of calcium homeostasis may represent an important event in the mechanism of action of insulin.     

The control of contraction activation by the membrane potential

Summary Force measurements under voltage-clamp control were performed in short toe muscles of the frog. The results show a) that the activation of force development and its repriming process can at least qualitatively be correlated to charge movement kinetics; b) that caffeine improves EC coupling by potentiating the potential dependent activation process.This work was supported by DFG (SFB 114 Bionach) and DAAD.     

Cardiac glycogen fractions in the ventricles of fasted and non-fasted,exercised rats

Zusammenfassung Vergleich von Glykogenfraktionen aus Ventrikeln männlicher Albinoratten, die 24 h gefüttert wurden, mit Nichgefütterten. Letztere verbrauchten meistens TCA (ungebundenes Glykogen) nach Bewegung, während gefütterte Ratten sowohl Rest-Glykogen (gebundenes) wie auch TCA Glykogen verbrauchten. Die Glykogenabnahme war im linken Ventrikel nach Bewegung grösser als im rechten.

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This investigation was supported by Public Health Service Research Grant No. HE 06747.     

The influence of proteolytic enzymes inhibitor on the course of lymphocyte transformation in vitro

Résumé Nous avons observé que l'inhibiteur d'enzymes protéolytiques (Zymofren-Specia) inhibe la transformation blastique des lymphocytes sensibilisés de cobaye évoquee par la phytohémagglutinine ou l'antigène. Nous n'avons pas observé d'influence ce de produit sur la consommation d'oxygène.