Novel non-thiazolidinedione, tyrosine-derived peroxisome proliferator-activated receptor γ agonis... more Novel non-thiazolidinedione, tyrosine-derived peroxisome proliferator-activated receptor γ agonists, GI 262570, GW 7845, GW 1929, developed by GlaxoSmithKline (GSK) along with pioglitazone and nisoldipine, were studied on currents through L-type voltage-dependent ...
In urinary bladder smooth muscle (UBSM), stimulation of beta-adrenergic receptors (beta-ARs) lead... more In urinary bladder smooth muscle (UBSM), stimulation of beta-adrenergic receptors (beta-ARs) leads to activation of the large-conductance Ca2+-activated K+ (BK) channel currents (Petkov GV and Nelson MT. Am J Physiol Cell Physiol 288: C1255-C1263, 2005). In this study we tested the hypothesis that the BK channel mediates UBSM relaxation in response to beta-AR stimulation using the highly specific BK channel inhibitor iberiotoxin (IBTX) and a BK channel knockout (BK-KO) mouse model in which the gene for the pore-forming subunit was deleted. UBSM strips isolated from wild-type (WT) and BK-KO mice were stimulated with 20 mM K+ or 1 microM carbachol to induce phasic and tonic contractions. BK-KO and WT UBSM strips pretreated with IBTX had increased overall contractility, and UBSM BK-KO cells were depolarized with approximately 12 mV. Isoproterenol, a nonspecific beta-AR agonist, and forskolin, an adenylate cyclase activator, decreased phasic and tonic contractions of WT UBSM strips in a concentration-dependent manner. In the presence of IBTX, the concentration-response curves to isoproterenol and forskolin were shifted to the right in WT UBSM strips. Isoproterenol- and forskolin-mediated relaxations were enhanced in BK-KO UBSM strips, and a leftward shift in the concentration-response curves was observed. The leftward shift was eliminated upon PKA inhibition with H-89, suggesting upregulation of the beta-AR-cAMP pathway in BK-KO mice. These results indicate that the BK channel is a key modulator in beta-AR-mediated relaxation of UBSM and further suggest that alterations in BK channel expression or function could contribute to some pathophysiological conditions such as overactive bladder and urinary incontinence.
Two experiments demonstrate the impact of the selfperformed actions during the encoding phase on ... more Two experiments demonstrate the impact of the selfperformed actions during the encoding phase on the amount of the learned information. People memorized more items if they had touched the stimuli during learning. The experiments differ from many of the classical studies testing embodiment of human memory in two main respects: First, the performed actions are completely unrelated to the essence of the learned stimuli, thus the results can not be explained by pure association-based facilitation. Second, the actions are performed during the encoding phase only, thus the results maybe directly linked to the nature of the encoded representations. The possible mechanisms that may underlie the observed influence are discussed shortly.
ABSTRACT The seeds of Tribulus terrestris L. show relatively low germination and a long period of... more ABSTRACT The seeds of Tribulus terrestris L. show relatively low germination and a long period of dormancy which results in bare patches in its field cultures decreasing the yield. The yield could successfully be enhanced by supplementation of green house seedlings ...
Abstract Computational modeling has played an important role in research on analogy since its ear... more Abstract Computational modeling has played an important role in research on analogy since its earliest days. This symposium will present some of the most recent developments in the computational modeling of analogy, including models of the process of analogy-making, ...
The central question in this paper is whether analogy-making automatically produces false memorie... more The central question in this paper is whether analogy-making automatically produces false memories for the mapped situations. Even in the case of analogy verification task where only analogical mapping between two given stimuli is required, analogical transfer seems to be automatically performed in both directions and as a consequence the transferred elements are wrongly recognized as part of the original stimuli. A computational model of the process is presented along with its simulation results and their verification in a psychological experiment. The predictions of the model are supported in the experiment.
Novel non-thiazolidinedione, tyrosine-derived peroxisome proliferator-activated receptor γ agonis... more Novel non-thiazolidinedione, tyrosine-derived peroxisome proliferator-activated receptor γ agonists, GI 262570, GW 7845, GW 1929, developed by GlaxoSmithKline (GSK) along with pioglitazone and nisoldipine, were studied on currents through L-type voltage-dependent ...
In urinary bladder smooth muscle (UBSM), stimulation of beta-adrenergic receptors (beta-ARs) lead... more In urinary bladder smooth muscle (UBSM), stimulation of beta-adrenergic receptors (beta-ARs) leads to activation of the large-conductance Ca2+-activated K+ (BK) channel currents (Petkov GV and Nelson MT. Am J Physiol Cell Physiol 288: C1255-C1263, 2005). In this study we tested the hypothesis that the BK channel mediates UBSM relaxation in response to beta-AR stimulation using the highly specific BK channel inhibitor iberiotoxin (IBTX) and a BK channel knockout (BK-KO) mouse model in which the gene for the pore-forming subunit was deleted. UBSM strips isolated from wild-type (WT) and BK-KO mice were stimulated with 20 mM K+ or 1 microM carbachol to induce phasic and tonic contractions. BK-KO and WT UBSM strips pretreated with IBTX had increased overall contractility, and UBSM BK-KO cells were depolarized with approximately 12 mV. Isoproterenol, a nonspecific beta-AR agonist, and forskolin, an adenylate cyclase activator, decreased phasic and tonic contractions of WT UBSM strips in a concentration-dependent manner. In the presence of IBTX, the concentration-response curves to isoproterenol and forskolin were shifted to the right in WT UBSM strips. Isoproterenol- and forskolin-mediated relaxations were enhanced in BK-KO UBSM strips, and a leftward shift in the concentration-response curves was observed. The leftward shift was eliminated upon PKA inhibition with H-89, suggesting upregulation of the beta-AR-cAMP pathway in BK-KO mice. These results indicate that the BK channel is a key modulator in beta-AR-mediated relaxation of UBSM and further suggest that alterations in BK channel expression or function could contribute to some pathophysiological conditions such as overactive bladder and urinary incontinence.
Two experiments demonstrate the impact of the selfperformed actions during the encoding phase on ... more Two experiments demonstrate the impact of the selfperformed actions during the encoding phase on the amount of the learned information. People memorized more items if they had touched the stimuli during learning. The experiments differ from many of the classical studies testing embodiment of human memory in two main respects: First, the performed actions are completely unrelated to the essence of the learned stimuli, thus the results can not be explained by pure association-based facilitation. Second, the actions are performed during the encoding phase only, thus the results maybe directly linked to the nature of the encoded representations. The possible mechanisms that may underlie the observed influence are discussed shortly.
ABSTRACT The seeds of Tribulus terrestris L. show relatively low germination and a long period of... more ABSTRACT The seeds of Tribulus terrestris L. show relatively low germination and a long period of dormancy which results in bare patches in its field cultures decreasing the yield. The yield could successfully be enhanced by supplementation of green house seedlings ...
Abstract Computational modeling has played an important role in research on analogy since its ear... more Abstract Computational modeling has played an important role in research on analogy since its earliest days. This symposium will present some of the most recent developments in the computational modeling of analogy, including models of the process of analogy-making, ...
The central question in this paper is whether analogy-making automatically produces false memorie... more The central question in this paper is whether analogy-making automatically produces false memories for the mapped situations. Even in the case of analogy verification task where only analogical mapping between two given stimuli is required, analogical transfer seems to be automatically performed in both directions and as a consequence the transferred elements are wrongly recognized as part of the original stimuli. A computational model of the process is presented along with its simulation results and their verification in a psychological experiment. The predictions of the model are supported in the experiment.
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Papers by Georgi Petkov