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Abstract. We studied cAMP-mediated exocytosis in rat pancreatic acinar cells. We monitored changes in the membrane capacitance (C), which reflects the granule fusion/retrieval process, with whole-cell patch-clamp capacitance measurement. The rise in cellular cAMP, caused indirectly by receptor activation by vasoactive intestinal polypeptide or directly by dibutyryl cyclic AMP, was able to induce an...
Abstract. The use of advanced patch-clamp recording techniques in brain slices, such as simultaneous recording from multiple neurons and recording from dendrites or presynaptic terminals, demands slices of the highest quality. In this context the mechanics of the tissue slicer are an important factor. Ideally, a tissue slicer should generate large-amplitude and high-frequency movements of the cutting...
Abstract. The regulatory myosin light chains (rMLCs) of mammalian skeletal muscle display protein diversity arising from the existence of different isotypes and protein phosphorylation. Two-dimensional electrophoresis and immunoblotting allowed us to identify three variants of the slow and fast rMLC isoforms (designated LC2s, LC2s1, LC2s2, and LC2f, LC2f1, LC2f2, respectively, from less to more acidic)...
Abstract. Cardiac hypertrophy alters the regional distribution of action potential duration by affecting the magnitude and kinetics of underlying ionic currents. In the present study, the effect of pressure-induced cardiac hypertrophy on the magnitude and kinetics of the L-type Ca2+ current (ICaL) was investigated in endo- and epicardial myocytes of the rat left ventricular free wall. Cardiac hypertrophy...
Abstract. Membrane fusion processes occur throughout the cell. Among those, exocytosis of secretory organelles is probably one of the fastest fusion events animal cells can achieve. Structural and functional studies have provided a conceptual framework and a starting point for our mechanistic understanding of how SNARE proteins may contribute to the final step in exocytosis.
Abstract. The plasma concentration of noradrenaline ([NA]) is higher than that of adrenaline ([A]) both in normal subjects and in heart transplant recipients (HTR). Since in both groups the myocardial density of 1-adrenergenic receptors is much greater than that of 2-adrenergenic receptors, the chronotropic response of a denervated heart to changes in plasma [NA] and [A] in the absence of reinnervation...
Abstract. Bartter syndrome is an autosomal recessive heterogeneous renal tubular disorder affecting NaCl reabsorption in the thick ascending limb of Henle's loop (TAL). The aim of this study was to elucidate the functional implications of mutations in the predominant human ROMK isoform in TAL, hROMK2, involved in Bartter syndrome type II. cRNA of flag-tagged hROMK2 and eight mutants identified in...
Abstract. Hemodynamic changes in early-pregnant and pseudopregnant rats are comparable, indicating that the trophoblast does not contribute to these changes. It is unclear whether the presence of the uterus is needed for the normal early-pregnancy hemodynamic adaptation. In this study we tested the hypothesis that uterine factors do not contribute to the systemic hemodynamic changes in early pseudopregnancy...
Abstract.Hamsters are frequently studied as a model of cardiomyopathy, but the electrophysiological properties of a hamster heart are not well defined. We examined rate-dependent changes in action potentials and underlying ionic mechanisms in isolated ventricular myocytes from hamster hearts using the whole-cell configuration of the patch clamp technique. At 0.1Hz stimulation, the mean action potential...
Abstract. Diadenosine polyphosphates are naturally occurring substances that facilitate tear secretion. The occurrence of these dinucleotides in human tears has been established and quantified by an HPLC technique and phosphodiesterase treatment. The concentration of these compounds found in tears was 2.02.2nM for diadenosine triphosphate (Ap3A), 108.018.3nM for diadenosine tetraphosphate (Ap4A) and...
Abstract. The metabolic active form of free fatty acids, long-chain acyl-coenzyme A (lc-acyl-CoA), binds to its 10-kDa binding protein with high affinity. In the present study, we investigated the content of lc-acyl-CoA binding protein (ACBP) in different skeletal muscle fibre types. Soleus had the highest expression of ACBP (0.330.02g mg protein1) and the content was as high as in heart muscle. The...
Abstract. Recently, the slowly-activating voltage-dependent K+ channel current (IKs) has been reported in the rat pancreatic acinus (RPA). IKs is modulated positively by ACh and secretin, Ca2+- and cAMP-mediated secretagogues, respectively. In this study, we investigated the effect of somatostatin (SS), a well-known inhibitory hormone of pancreatic fluid secretion, on IKs in RPAs. The whole-cell patch...
Abstract. The HvCNG channel from the moth Heliothis virescens is highly sensitive to cAMP concentrations ranging between 0.1M and 5M. This HvCNG channel was over-expressed in Spodoptera frugiperda (Sf.9) cells to measure endogenous cAMP levels. Hyperpolarization-activated inward currents were measured in the whole-cell patch-clamp configuration with pipettes filled with different cAMP concentrations...
Abstract. The study addressed the question of why in adult ventricular rat cardiomyocytes ERK activation is required for the hypertrophic stimulation caused by angiotensin II but not in the case of -adrenoceptor stimulation. We therefore compared in the same culture system the intracellular signaling steps that are involved in inducing the hypertrophic growth evoked by stimulating either of these...
Abstract. We used implanted miniature data loggers to measure brain and arterial blood temperatures every 5min for up to 15days in four free-ranging oryx (Oryx gazella) in their natural habitat. Globe temperatures exceeded 45C and average peak radiant heat load was 800Wm2. Arterial blood temperature exhibited a moderate amplitude nychthemeral rhythm of 1.80.3C (mean SD). The amplitude of the nychthemeral...
Abstract. We investigated the effects of carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP), a protonophore and uncoupler of mitochondrial oxidative phosphorylation in mitochondria, on plasma membrane potential and ionic currents in bovine aortic endothelial cells (BAECs). The membrane potential and ionic currents of BAECs were recorded using the patch-clamp technique in current-clamp and voltage-clamp...
The intramuscular microdialysate lactate concentration during dynamic exercise with various degrees of blood flow restriction and its relation to lactate concentration in skeletal muscle biopsy and venous blood were studied. Nine healthy males performed three one-legged knee extension exercises (Ex13). Blood flow was restricted stepwise by applying supra-atmospheric pressure over the working leg....
Abstract. The present study investigated the effect of redox agents on Ca2+-activated Cl currents (ICl(Ca)) recorded in smooth muscle cells isolated from rabbit portal vein. In perforated-patch experiments on portal vein cells the amplitude of ICl(Ca) evoked by either spontaneous release of Ca2+ from internal stores or Ca2+ influx through voltage-dependent Ca2+ channels was markedly and irreversibly...
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