Calcium channel modulation by beta-adrenergic neurotransmitters in the heart

Calcium ions play a crucial role in the regulation of the heart beat. During each action potential Ca2+ ions flow into the cell and are directly and indirectly involved in generation of pacemaker potentials and of contractile force. Adrenergic and cholinergic neurotransmitters modulate Ca2+ influx. The most detailed analysis has been made on the mechanism of the beta-adrenergic effect on calcium channels in cardiac cell membranes. This is briefly summarized in a personal account, while for more detailed information the reader is referred to more extensive recent reviews.     

Protection against mercuric chloride nephropathy by sodium selenite in the rat]

Daily intraperitoneal injection of 2.5 or 5 mumole HgCl2 to male Rats weighing 250 to 350 g induces an early intense increase of urine gamma-glutamyl transferase activity. In the same conditions, equimolecular administration of sodium selenite and mercuric chloride induces no increase of the enzymuria for the low dose: for the high dose- a minor and more persistent increase of urine GGT is observed. Thus, the activity of urines GGT allows, in vivo, to establish that sodium selenite protects Rat kidney against toxic effects of mercuric chloride.     

Effect of some substances on the mitochondrial swelling induced by diphtheria toxin in chicken embryo heart cell cultures

Riassunto E stato studiato l'effetto di alcune sostanze sul rigonfiamento mitocondriale indotto dalla tossina difterica. Il KCN, l'Amytal e l'azide sodica prevengono il rigonfiamento. ATP e sieroalbumina ripristinano, entro certi limiti, la forma filamentosa in mitocondri rigonfiati dalla tossina difterica.     

Formation of the neuromuscular junction in cultures of rat embryonic cells]

The morphological evidence of the primary nerve muscle contacts are described. They consist of areas of cholinesterase activity (detected histochemically) localized on the myotube membranes and of mutiple clusters of ACh receptors whose 125I-alpha-bungarotoxin binding sites are revealed by radio-autography. After the stage of the primary nerve muscle contacts, some of which seem transient, characteristic neuromuscular junctions appear. These neuromuscular junctions which possess subneural infoldings are similar to the end-plates of the Rat in vivo.     

Suppressor effect induced by sodium periodate on the antibody response of mouse splenic cells in vitro : inhibition of this effect by sodium borohydride]

Mild oxidation of mouse spleen cells by sodium periodate induces blastogenesis. Concomitantly, the in vitro response of these cells to sheep red blood cells is inhibited. Exposure of spleen cells to sodium borohydride following periodate treatment reduces blastogenesis and restores the immune response.     

Action potentials of the guinea pig heart in sodium deficient solutions

Zusammenfassung Es werden Aktionspotentiale vom Meerschweinchenvorhof in Badelösungen verschiedener Na-Konzentrationen mittels intrazellulärer Elektroden registriert. Während das Aktionspotential desVentrikels relativ unempfindlich gegen Veränderungen der Na-Konzentration bleibt^{4, 6}, lässt sich die «Na-Hypothese» für denVorhof anwenden.

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Aided by a grant from the Italian Consiglio Nazionale delle Ricerehe.     

Immunofluorescent localization of the types of collagen synthesized in the embryonic mouse tooth germ]

The different types of collagen synthesized by embryonic Mouse tooth germs were analysed using an immunohistiological method. The tooth germs were shown to synthesize at least three genetically distinct collagen types: I, III and IV.