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  • 1
    Electronic Resource
    Electronic Resource
    Multiple transport modes of the cardiac Na + /Ca 2+ exchanger (2004)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 427 (2004), S. 544-548 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The cardiac Na+/Ca2+ exchanger (NCX1; ref. 2) is a bi-directional Ca2+ transporter that contributes to the electrical activity of the heart. When, and if, Ca2+ is exported or imported depends on the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature02271
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  • 2
    Electronic Resource
    Electronic Resource
    Caffeine and histamine-induced oscillations of K(Ca) current in single smooth muscle cells of rabbit cerebral artery (1995)
    Springer
    Pflügers Archiv 431 (1995), S. 91-100 
    Details
    ISSN: 1432-2013
    Keywords: Ca2+ oscillation ; Caffeine ; Histamine ; Ryanodine ; Ca2+-induced Ca2+ release ; Ca2+-activated K+ current ; Cerebral artery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the present experiment, we characterized the intracellular Ca2+ oscillations induced by caffeine (1 mM) or histamine (1–3 μM) in voltage-clamped single smooth muscle cells of rabbit cerebral (basilar) artery. Superfusion of caffeine or histamine induced periodic oscillations of large whole-cell K+ current with fairly uniform amplitudes and intervals. The oscillatory K+ current was abolished by inclusion of ethylenebis(oxonitrilo)tetraacetate (EGTA, 5 mM) in the pipette solution. Caffeine- and histamine-induced periodic activation of the large-conductance Ca2+-activated K+ [K(Ca)] channel was recorded in the cell-attached patch mode. These results suggest that the oscillations of K+ current are carried by the K(Ca) channel and reflect the oscillations of intracellular Ca2+ concentration ([Ca2+]i). Ryanodine (1–10 μM) abolished both caffeine- and histamine-induced oscillations. Caffeine- induced oscillations were abolished by the sarcoplasmic reticulum Ca2+-adenosine 5′-triphosphatase (Ca2+-ATPase) inhibitor, cyclopiazonic acid (10 μM), and a high concentration of caffeine (10 mM). Inclusion of heparin (3 mg/ml) in the pipette solution blocked histamine-induced oscillations, but did not block caffeine-induced oscillations. By the removal of extracellular Ca2+, but not by the addition of verapamil and Cd2+, the caffeine-induced oscillations were abolished. Increasing Ca2+ influx rate increased the frequencies of caffeine-induced oscillations. Spontaneous oscillations were also observed in cells that were not superfused with agonists, and had similar characteristics to the caffeine-induced oscillations. From the above results, it is concluded, that in smooth muscle cells of the rabbit cerebral (basilar) artery, ryanodine-sensitive Ca2+-induced Ca2+ release pools play key roles in the generation of caffeine- and histamine-induced intracellular Ca2+ oscillations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374381
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of myosin light chain kinase inhibitors on carbachol-activated nonselective cationic current in guinea-pig gastric myocytes (1997)
    Springer
    Pflügers Archiv 434 (1997), S. 346-353 
    Details
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Nonselective cationic current ; Carbachol ; Myosin light chain kinase ; ML-7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effects of myosin light chain kinase inhibitors on muscarinic stimulation-activated nonselective cationic current (I CCh) in guinea-pig gastric antral myocytes were studied using the whole-cell patch-clamp technique. I CCh was induced by carbachol (CCh, 50 μM) at a holding potential of –30 mV or –60 mV. ML-7, a chemical inhibitor of myosin light chain kinase (MLCK), inhibited I CCh concentration dependently in a reversible manner (53 ± 8.6% at 1 μM, mean ± SE, n = 11). In addition, amplitudes of I CCh were only 37 ± 2.7% of the daily control values following the addition of a peptide inhibitor of MLCK to the pipette solution. On the other hand, ML-7 had an inhibitory effect on voltage-operated Ca2+ channel current. The peak value of Ba2+ current at 0 mV was reduced to 35 ± 7.4% (n = 9) by 3 μM of ML-7. As I CCh is known to have an intracellular Ca2+ dependence, we tried to exclude the possibility that ML-7 inhibited I CCh indirectly via suppression of Ca2+ current and the similar inhibitory effects of ML-7 on I CChwere confirmed under the following conditions: (1) clamp of membrane potential at –60 mV; (2) clamp of intracellular [Ca2+] to 1 μM by 10 mM BAPTA; (3) pre-inhibition of Ca2+ channel by verapamil. Different from the effects on I CCh, ML-7 barely inhibited the same cationic current induced by guanosine 5’-O-(3-thiotriphosphate) (GTP[γS], 0.2 mM) in the pipette solution. These results suggest that a Ca2+/calmodulin-MLCK-dependent pathway can modulate the activation of I CCh in guinea-pig gastric antral myocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050407
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  • 4
    Electronic Resource
    Electronic Resource
    Volume-sensitive chloride current activated by hyposmotic swelling in antral gastric myocytes of the guinea-pig (1997)
    Springer
    Pflügers Archiv 435 (1997), S. 9-19 
    Details
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Cell volume ; Chloride current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The characteristics of volume-sensitive chloride current (I Cl) induced by osmotic cell swelling were studied using the whole-cell patch-clamp technique and cell diameters of antral circular guinea-pig myocytes were simultaneously measured under isosmotic and hyposmotic conditions by using a video image analysis system. At –60 mV, osmotic cell swelling (200 mosmol/l) activated a sustained inward current. Instantaneous current/voltage (I-V) relations obtained by step voltage pulses showed an outward rectification. At potentials above +40 mV, the current exhibited time-dependent decay. The outward current amplitude was decreased and the reversal potential was shifted to more positive potentials by replacement of external Cl– with gluconate–, while the current amplitude and the I/V relation were not affected by replacing extracellular Na+ with N-methyl-D-glucamine. The anion permeability sequence of the swelling-induced current was I– (1.80) 〉 Br– (1.31) 〉 Cl– (1) 〉 F– (0.85) 〉 gluconate– (0.18). The I Cl was effectively inhibited by the Cl– channel blockers, 4,4′-diisothiocyanatostilbene-2,2’-disulphonic acid (DIDS, 100 μM), and niflumic acid (10 μM). DIDS suppressed outward current more effectively than inward current. Also, the I Cl was dose-dependently inhibited by arachidonic acid, an unsaturated fatty acid and also inhibited by other unsaturated fatty acids (linoleic acid and oleic acid) but not by stearic acid, a saturated fatty acid. The inhibitory effect of arachidonic acid on I Cl was not prevented by indomethacin, a cyclo-oxygenase inhibitor and chelerythrine, a protein kinase C inhibitor. Under whole-cell patch-clamp conditions, the cell diameter was continuously measured using video image analysis, which reflects the change in cell volume. A hyposmotic-stimulation-induced increase of cell diameter was followed by I Cl activation. In intact single gastric myocytes, relatively severe hyposmotic (176 mosmol/l) superfusing solution increased the cell diameter and the pretreatment with DIDS or with niflumic acid significantly potentiated the above effect of hyposmotic superfusion. These results suggest that volume-sensitive outwardly rectifying chloride current (I Cl) is present in guinea-pig gastric myocyte and the I Cl may play a role in smooth muscle cell volume regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050478
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  • 5
    Electronic Resource
    Electronic Resource
    Protein kinase C mediates the desensitization of CCh-activated nonselective cationic current in guinea-pig gastric myocytes (1998)
    Springer
    Pflügers Archiv 436 (1998), S. 1-8 
    Details
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Nonselective cationic current ; Carbachol (CCh) ; Protein kinase C (PKC) ; Desensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The possibility of the protein kinase C (PKC) pathway being a mechanism underlying the desensitization of carbachol- (CCh-)activated nonselective cationic current (I CCh) was investigated in a study of guinea-pig gastric myocytes. Using the conventional whole-cell patch-clamp technique with symmetrical CsCl-rich solution in pipette and bath, I CCh was induced by bath application of 50 µM CCh. With 0.5 mM EGTA [ethyleneglycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid] in the pipette solution (0.5 mM [EGTA]i), I CCh decayed spontaneously (desensitization of I CCh) to around 20% within 10 min. Desensitization of I CCh was significantly attenuated with 2 mM [EGTA]i. At a concentration of 20 µM OAG (1-oleoyl-2-acetyl-sn-glycerol), a PKC activator, inhibited I CCh at 0.5 mM [EGTA]i but far less at 2 mM [EGTA]i (18% and 81% of control, respectively). The same cationic current induced by intracellular guanosine-5′-O-(3-thiotriphosphate) (GTP[γ-S]) was not inhibited by OAG with 0.5 mM [EGTA]i. The pretreatment of gastric myocytes with PKC inhibitors, either 1 µM chelerythrine or 1 µM peptide inhibitor, attenuated the desensitization of I CCh. [Ca2+]i was also measured by single cell microfluorometry using fura-2. Under CCh stimulation with 2 mM [EGTA]i, [Ca2+]i did not increase above 100 nM while it increased to around 260 nM with 0.5 mM [EGTA]i. These results suggest that the desensitization of I CCh is partly due to the Ca2+-dependent PKC pathway in guinea-pig gastric myocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050597
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of stretch on calcium channel currents recorded from the antral circular myocytes of guinea-pig stomach (1996)
    Springer
    Pflügers Archiv 432 (1996), S. 159-164 
    Details
    ISSN: 1432-2013
    Keywords: Key words Ca channel current ; Gastric myocytes ; Stretch ; Membrane capacitance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of membrane stretch on voltage-activated Ba2+ current (I Ba) was studied in antral circular myocytes of guinea-pig using the whole- cell patch-clamp technique. The changes in cell volume were elicited by superfusing the myocytes with anisosmotic solutions. Hyposmotic superfusate (202 mosmol/l) induced cell swelling and increased peak values of I Ba at 0 mV (from −406.6 ± 45.5 pA to −547.5 ± 65.6 pA, mean ± SEM, n = 8) and hyperosmotic superfusate (350 mosmol/l) induced cell shrinkage and decreased peak values of I Ba at 0 mV (to −269.5 ± 39.1 pA, n = 8). Such changes were reversible and the extent of change was dependent on the osmolarity of superfusate. The values of normalized I Ba at 0 mV were 1.43 ± 0.04, 1.30 ± 0.06, 1.23 ± 0.04, 1.19 ± 0.04, 1 and 0.68 ± 0.06 at 202, 220, 245, 267, 290 and 350 mosmol/l, respectively (n = 8). I Ba was almost completely blocked by nicardipine (5 μM) under hyposmotic conditions. The values of steady-state half-inactivation voltage (−37.7 ± 3.3 and −36.5 ± 2.6 mV, under control and hyposmotic conditions, respectively) or the half-activation voltage (−13.6 ± 2.3 and −13.9 ± 1.9 mV) of I Ba were not significantly changed (P 〉 0.05, n = 6). Cell membrane capacitance was slightly increased from 50.00 ± 2.86 pF to 50.22 ± 2.82 pF by a hyposmotic superfusate (P 〈 0.05, n = 6). It is suggested that cell swelling increases voltage-operated L-type calcium channel current and that such a property is related to the response of gastric smooth muscle to mechanical stimuli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050119
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