Search results for "Tassi"
showing 10 items of 997 documents
Der Einflu� von Monojodessigs�ure auf das Aktionspotential des Rattenzwerchfells
1959
1. The action of iodoacetic acid (IA) was studied on the isolated rat diaphragm at 20–22° C. Membrane and action potentials were led off with intracellular microelectrodes. 2. IA causes a contracture which is complete in 4 hours. As long as t he contracture develops, the membrane potential remains constant. A contracture identical with that seen in a normal preparation can be produced by IA in the presence of isotonic K2SO4. 3. The amplitude of the action potential is only slightly reduced during the first two hours after addition of IA. The duration of the action potential is significantly increased. Finally, action potentials with a plateau are obtained which resemble those of normal vent…
Tonic inhibitory action by nitric oxide on spontaneous mechanical activity in rat proximal colon: involvement of cyclic GMP and apamin-sensitive K+ c…
1999
The cellular mechanisms by which endogenous nitric oxide (NO) modulates spontaneous motility were investigated in rat isolated proximal colon. The mechanical activity was detected as changes in intraluminal pressure. Apamin (1–100 nM) produced a concentration-dependent increase in the amplitude of the spontaneous pressure waves. The maximal contractile effect was of the same degree as that produced by Nω-nitro-L-arginine methyl ester (L-NAME) (100 μM) and the joint application of apamin plus L-NAME had no additive effects. Apamin (0.1 μM) reduced the inhibitory effects (i.e. reduction in the amplitude of the pressure waves) induced by sodium nitroprusside (SNP) (1 nM–10 μM) or 8-Br-cyclic G…
Effects of Quinine and Quinidine on the Transient Outward and on the L-Type Ca<sup>2+</sup> Current in Rat Ventricular Cardiomyocytes
2002
The effects of the enantiomers quinine and quinidine on the transient outward current (I<sub>to</sub>) and on the L-type Ca<sup>2+</sup> current (I<sub>Ca</sub>) were investigated in rat ventricular cardiomyocytes using the patch-clamp technique. At a stimulation frequency of 2 Hz, both quinine and quinidine depressed the magnitude of I<sub>to</sub> and I<sub>Ca</sub>; the half-maximal effects on I<sub>to</sub> were achieved at 11 and 15 µmol/l, respectively, and those on I<sub>Ca</sub> at 14 and 10 µmol/l, respectively. At 0.2 Hz, both drugs depressed the magnitude of I<sub>to</sub>, but not tha…
Akute Trijodthyroninwirkungen auf den Kalium-Umsatz von Meerschweinchenvorh�fen
1963
Akute Wirkungen von Trijodthyronin (T3 10−6 und 10−5 g/ml) auf den K-Umsatz von Meerschweinchenvorhofen wurden mit Hilfe von 42K in vitro untersucht. Veranderungen der intracellularen Ionenkonzentrationen wurden nur nach 2 Std dauernder Einwirkung von T3 10−5 g/ml beobachtet. Zu diesem Zeitpunkt war die intracellulare K-Konzentration signifikant erhoht. T3 10−6 g/ml steigerte den K-Umsatz des Meerschweinchenvorhofs. K-Influx und -Efflux waren nach 2 Std Einwirkungsdauer in gleichem Ausmas gesteigert, die K-Permeabilitat war betrachtlich erhoht. Zu spateren Zeitpunkten nahmen K-Influx und -Efflux ab. T3 10−5 g/ml verminderte den K-Umsatz des Meerschweinchenvorhofs. Der K-Efflux war, vor alle…
Änderungen des Elektrolytgehaltes von Erythrozyten und Plasma bei nephrektomierten Ratten
1957
After two-stage nephrectomy in rats the potassium concentration in the red blood corpuscles (RBC) decreases from 10.6 ± 0.3 to 5.5 ± 0.3 mEq per 100 ml of RBC within 48 h. The decrease is accompanied by a much smaller increase in the plasma potassium concentration; the hyperkaliemia in nephrectomized rats is less pronounced than in nephrectomized dogs or anuric humans. Na+ in RBC increases by about 44% after nephrectomy; while there is only a very slight decrease of Na+ in plasma. Plasma chlorides drop from 10.92 ± 0.08 mEq/100 ml of plasma to 6.00 ± 0.81 mEq % within 48 h after nephrectomy. RBC chlorides tend to increase again after an initial drop from 5.22 ± 0.07 to 3.82 ± 0.90 mEq% with…
Inhibition of neuroeffector transmission in human vas deferens by sildenafil
2000
Sildenafil (0.1 - 30 microM), a cyclic GMP phosphodiesterase 5 (PDE 5) inhibitor, induced inhibition of electrically evoked contractions of ring segments of human vas deferens from 34 vasectomies. Zaprinast (0.1 - 100 microM), another PDE 5 inhibitor, and the nitric oxide (NO) donor sodium nitroprusside (SNP) (0.1 - 100 microM) had no effect on neurogenic contractions. The inhibition induced by sildenafil was not modified by the inhibitor of guanylate cyclase 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) (1 - 30 microM) but it was abolished by the K(+) channel blockers tetraethylammonium (TEA, 1 mM), iberiotoxin (0.1 microM) and charybdotoxin (0.1 microM). Sildenafil, zaprinast and SNP…
K+ and Na+ effects on the gelation properties of κ-Carrageenan
2004
The effects of K(+), Na(+) ions and their mixture on the conformational transition and macroscopic gel properties of kappa-Carrageenan system have been studied using different experimental techniques. The macroscopic gelation properties of kappa-Carrageenan were found to be dependent upon cosolute type. Indeed, a more ordered and strong gel was obtained in the presence of K(+) with respect to Na(+) ions. The gel properties obtained using mixtures of two cosolutes are shown to depend on the [K(+)]/[Na(+)] ratio.
Quantum chemical modelling of perovskite solid solutions
2000
In line with our previous study (Eglitis R I et al 1998 J. Phys.: Condens. Matter 10 6271) for a single Nb impurity and Nb clusters in KTaO3 we present here the results of calculations for a series of perovskite KNbx Ta 1−x O3 (KTN) solid solutions (x = 0, 0.125, 0.25, 0.75, and 1). The quantum chemical method of the intermediate neglect of the differential overlap (INDO) combined with the large unit cell (LUC) periodic model is used. According to the INDO calculations, Nb impurity becomes off-centre in KTaO3 already at the lowest studied Nb concentration. Its off-centre displacement is in a good agreement with XAFS measurements. We compare our results with previous FP-LMTO calculations. Pe…
Prevention of the acute neurotoxic effects of phenytoin on rat peripheral nerve by H7, an inhibitor of protein kinase C.
1992
Abstract The neurotoxic effects of a single dose of phenytoin (150 mg/kg body weight) alone or 30 min after H7 (a protein kinase C inhibitor) injection (20 mg/kg body weight) were investigated in terms of peripheral neuromuscular function and Na + ,K + -ATPase activity of the sciatic nerve. This intraperitoneal injection of phenytoin induced complete blockade of muscle action potentials in the dorsal segmental muscles of the rat tail evoked by electric stimulation of the caudal nerve and a 40% decrease in the Na + ,K + -ATPase activity of the rat sciatic nerve when compared with control values, measured as the difference between total and ouabain-insensitive ATPase activity. Prior administr…
Modulation of neuronal phospholipase D activity under depolarizing conditions
1999
Neuronal phospholipase D (PLD) activity was hypothesized to be involved in vesicle trafficking and endocytosis and, possibly, transmitter release. We here report that prolonged depolarization of rat hippocampal slices by potassium chloride (KCl) or 4-aminopyridine inhibited PLD activity. Similarly, PLD activity in rat cortical synaptosomes was significantly inhibited by depolarizing agents including veratridine and ouabain. Inhibition of calcium/calmodulin kinase II (CaMKII) which positively modulates synaptosomal PLD activity [Sarri et al. (1998) FEBS Lett. 440, 287-290] by KN-62 caused a further reduction of PLD activity in depolarized synaptosomes. Depolarization-induced inhibition of PL…