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Histological and functional studies were performed on a preparation of rat colonic mucosa from which the myenteric and submucosal plexus were removed. This preparation, referred to as the mucosa preparation, was used to investigate the potential influence of the mucosal plexus on electrolyte transport. Two neuropharmacologically active agents were used: sea(More)
The breakdown of phosphatidylinositol 4,5-bisphosphate (PIP2) by the action of a phosphoinositide-specific phospholipase C is a key event in the signal transduction mechanism of microvillar photoreceptors. The enzymatic activity of phospholipase C from photoreceptor cell membranes of the cuttlefish Sepia officinalis was measured at different concentrations(More)
Magnetic turbulence is observed at the beginning of the current quench in intended TEXTOR disruptions. Runaway electron (RE) suppression has been experimentally found at magnetic turbulence larger than a certain threshold. Below this threshold, the generated RE current is inversely proportional to the level of magnetic turbulence. The magnetic turbulence(More)
In morphologisch unterschiedlichen Biopsieproben aus der Fundus-, Antrum- und Duodenalschleimhaut von insgesamt 134 Personen wurde die basale und histaminstimulierte Adenylat-Cyclaseaktivität untersucht. Basale und stimulierte Adenylat-Cyclaseaktivität der Schleimhaut des oberen Gastrointestinaltrakts war log-normal verteilt. Nur die Adenylat-Cyclase der(More)
The effect of several chemical reagents on the sodium current was studied in voltage-clamped single nerve fibers of the frog. The oxidants halazone and hypochlorous acid drastically inhibited inactivation. Their effect was similar to that of chloramine T (Wang, 1984a). The curve relating the steady-state inactivation parameter h infinity to the conditioning(More)
The distribution of cyclic 3',5'-nucleotide phosphodiesterase activity was determined in photoreceptor cells of the fly Calliphora erythrocephala. With cAMP as substrate, staining was most intense within the phototransducing region of these cells, the rhabdomeral microvilli and also in the extracellular space surrounding the microvilli and in the(More)
Biopsy specimens of human fundic mucosa from 96 subjects were assayed for adenylate cyclase activity to characterize specificity of the histamine receptor with selective agonists and antagonists in vitro, and to study the effect of cimetidine therapy. Histamine and the selective histamine H2-receptor agonist dimaprit were almost equally potent throughout(More)
To test the possible role of lysine residues in Na channel function the effects of several imidoesters on Na and gating currents were studied in voltage-clamped single frog nerve fibers. Mono- and bisimidoesters were used. These reagents modify amino groups exclusively and do not change the net charge. The three bisimidoesters used easily introduce(More)
The venom of the African scorpion Leiurus quinquestriatus was subjected to high-performance ion-exchange chromatography. Among a large number (greater than 25) of small proteins and other substances, a protein component of approx. 6500 Da was purified. The effect of this toxin was tested on single myelinated nerve fibres of the frog Rana esculenta. Toxin(More)
Sea anemone toxin II (ATX II) is a useful tool for investigation of sodium channels in excitable membranes. Coupling of ATX II with microperoxidase, a heme-octapeptide, is described. The isolated cross-linked product possesses both toxic and peroxidase activity. The lowest concentration of the modified toxin that affects the action potential and the(More)