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  • 1
    Electronic Resource
    Electronic Resource
    Role of calmodulin in the activation of carbachol-activated cationic current in guinea-pig gastric antral myocytes (1995)
    Springer
    Pflügers Archiv 430 (1995), S. 757-762 
    Details
    ISSN: 1432-2013
    Keywords: Gastrointestinal myocytes ; Nonselective cation channels ; Carbachol ; Calmodulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In mammalian gastrointestinal myocytes, it is known that muscarinic stimulation activates nonselective cation channels through a G-protein and a Ca2+dependent pathway. We recorded inward cationic currents following application of carbachol (I CCh) to guinea-pig gastric myocytes, which were held at −20 mV using the whole-cell patch-clamp method. I CCh was suppressed by nicardipine or removal of Ca2+ from the bath solution. The peak value of inward current induced by repetitive applications of carbachol (CCh) decreased progressively (run-down phenomenon). This run-down was significantly alleviated by the addition of calmodulin to the pipette solution (0.15 mg/ml) or by using the perforated-patch whole-cell voltage-clamp technique. Moreover, W-7 [N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide], a calmodulin antagonist, was a reversible inhibitor of I CCh. However, W-7 had only a weak inhibitory effect on the same cationic current which was induced by guanosine 5′-O-(3-thiotriphosphate) (GTP[γS] 0.2 mM) in the pipette solution. This GTP[γS]-induced cationic current was still markedly suppressed by the Ca2+-free bath solution. W-7 itself had a weak inhibitory effect on voltage-operated Ca2+ channels as well as the effects on I CCh. These data suggest that multiple Ca2+-dependent pathways are involved in the activation of CCh-gated cation channels in guinea-pig antral myocytes and a Ca2+/calmodulin-dependent pathway would be one of them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386173
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  • 2
    Electronic Resource
    Electronic Resource
    Inhibitory effect of phorbol 12, 13 dibutyrate on carbachol-activated nonselective cationic current in guinea-pig gastric myocytes (1997)
    Springer
    Pflügers Archiv 434 (1997), S. 505-507 
    Details
    ISSN: 1432-2013
    Keywords: Key words Carbachol ; Nonselective cationic current ; Protein kinase C ; smooth muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effect of protein kinase C (PKC) on carbachol (CCh)-activated nonselective cationic current (I CCh) was investigated in guinea-pig gastric myocytes using a PKC activator, phorbol 12, 13 dibutyrate (PDBu). Pretreatment with 1 μ M PDBu suppressed I CCh by 96.5 ± 2.9% (n = 14) in a reversible manner in nystatin-perforated mode. In the presence of 1 μM chelerythrine , a PKC inhibitor, inhibition of I CChby PDBu was not seen. In whole-cell mode, the inhibition of I CCh by PDBu was dependent on intracellular MgATP. In the presence of MgATP in the pipette, PDBu decreased I CCh by 98.8 ± 1.2% (n = 5) as was observed in nystatin-perforated mode. However, PDBu had little effect on I CCh in the absence of MgATP in the pipette; the extent of inhibition was 12.7 ± 4.3% (n = 8). PDBu also suppressed the generation of cationic current induced by intracellularly perfused GTP[γS]. In the PDBu-pretreated group (n = 9) and PDBu-untreated control group (n = 6), GTP[γS]-induced currents were 6.7 ± 2.4 pA and 236 ± 23 pA, respectively. These results suggest that PKC modulates I CCh at postreceptor sites via protein phosphorylation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050429
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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