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  • 1
    Electronic Resource
    Electronic Resource
    Involvement of calcium in calcium-current inactivation in smooth muscle cells from rat vas deferens (1987)
    Springer
    The journal of membrane biology 100 (1987), S. 13-19 
    Details
    ISSN: 1432-1424
    Keywords: smooth muscle cells ; Ca channel ; whole cell recording ; inactivation ; Ca dependency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Ca-channel currents were recorded in Cs-loaded single smooth muscle cells from rat vas deferens to define the dependence of the inactivation time course on Ca concentration. The decay of Ca-channel current obtained in a Ba2+- or Sr2+-containing external solution during long voltage-clamp pulses was much slower than that in a Ca-containing solution. The difference was not due to a change in the surface potential of the membrane as judged from the steady-state activation and inactivation curves. When Ca was the charge carrier, increasing external Ca concentration slightly accelerated the rate of inactivation. In addition, the rate of inactivation of Ca-channel current in 10.8mm Ba was also accelerated by adding Ca to the external solution in a concentration-dependent manner. The time course of Ca-current inactivation was slowed when the cells were dialyzed with a high concentration of citrate, a Ca-chelating agent. From these results, we concluded that a mechanism regulated by intracellular Ca activity plays a role in the inactivation of Ca channels in smooth muscle. The Ca-dependent process may protect against Ca overload by regulating Ca entry in smooth muscle cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02209136
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of calcitonin gene-related peptide (CGRP) on Ca2+-channel current of isolated smooth muscle cells from rat vas deferens (1992)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 346 (1992), S. 515-522 
    Details
    ISSN: 1432-1912
    Keywords: Calcitonin gene-related peptide ; Smooth muscle cells ; Vas deferens - Membrane currents ; Ca2+ channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of calcitonin gene-related peptide (CGRP), a putative non-adrenergic non-cholinergic neutrotransmitter on the electrical properties of the cell membrane, were investigated in enzymically dispersed smooth muscle cells from rat vas deferens. Under current clamp conditions, CGRP (up to 10−7 M) did not induce significant changes in membrane potentials or input resistance in the resting state. The configurations of action potentials elicited by depolarizing current pulses were also unaffected, except that a prolongation of the duration of the action potentials by a high dose (10−7 M) of CGRP was observed in some of the cells. Under whole cell voltage clamp conditions, the transient and sustained K+ currents, activated by depolarizing voltage-steps, were apparently decreased in the presence of 10−9 to 10−7 M CGRP. The peptide increased the voltage-gated Ca2+ current in cells loaded with 145 mM Cs+ solution in order to block the K+ currents. The voltage-dependency of the peak Ca2+ current was not changed by CGRP. Ba2+ (10.8 mM) was used as a charge carrier for the Ca2+-channel current to clarify further the effects of CGRP on the properties of the current. CGRP (10−8 M) delayed the inactivation time course of the Ca2+-channel current and slowed the recovery from inactivation. The peptide did not affect the steady-state inactivation measured by changing the holding potential. The Ca2+-channel current in the presence of CGRP was suppressed by nicardipine (10−6 M) to the same extent as the current under control conditions. The results suggest that CGRP modifies the L-type Ca2+ channel in smooth muscle cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169006
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Screening for colorectal cancer (2000)
    Springer
    Diseases of the colon & rectum 43 (2000), S. S78 
    Details
    ISSN: 1530-0358
    Keywords: Screening ; Colorectal cancer ; Immunochemical fecal occult blood test ; Evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: Screening for colorectal cancer using a guaiac-based fecal occult blood, or Hemoccult®, test has been demonstrated to reduce colorectal cancer mortality. However, the magnitude of effectiveness is relatively low because of poor sensitivity of the Hemoccult® test. The immunochemical fecal occult blood test has been shown to be much more sensitive than the Hemoccult® test in detecting preclinical colorectal cancer in an asymptomatic population. The purpose of this article is to discuss the validity of the immunochemical fecal occult blood test and the efficacy of a population-based screening program using the test. METHODS: Relevant articles were primarily identified through MEDLINE search. Review was focused on the studies of population screening programs with the immunochemical fecal occult blood test. RESULTS: Sensitivities for colorectal cancer calculated in the same population were reported to be 67 to 89 percent and only 33 to 37 percent for the immunochemical test and Hemoccult® test, respectively. Case-control studies and other observational studies showed that screening programs using the immunochemical fecal occult blood test by hemagglutination reaction would reduce the risk of dying of colorectal cancer by 60 percent or more for those screened annually compared with those unscreened. It was also shown that a screening strategy using the immunochemical fecal occult blood test had the best cost-effectiveness ratio among the methods available. Nearly 5 million persons are currently screened per year in Japan, yielding 0.15 to 0.2 percent colorectal cancer cases among persons with positive fecal occult blood test results. CONCLUSIONS: These results strongly suggest that a screening program with immunochemical fecal occult blood test has promising advantages in terms of effectiveness over programs with the Hemocult® test. More stress is warranted on introduction of immunochemical fecal occult blood testing as a screening test in place of the guaiac fecal occult blood test.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02237230
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    Paper (German National Licenses)
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