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  • Articles: DFG German National Licenses  (7)
  • Life and Medical Sciences  (5)
  • Ventricle  (2)
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  • Articles: DFG German National Licenses  (7)
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Years
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Characteristics of the delayed rectifier K current compared in myocytes isolated from the atrioventricular node and ventricle of the rabbit heart (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 713-722 
    Details
    ISSN: 1432-2013
    Keywords: Atrioventricular node ; Myocyte ; Ventricle ; Delayed rectifier potassium current (I k) ; E-4031
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The delayed rectifier potassium current (I K) is known to be important in action potential repolarisation and may contribute to the diastolic pacemaker depolarisation in pacemaker cells from the heart. In this study, using whole-cell patch clamp, we investigated the characteristics ofI K in morphologically normal cells from the atrioventricular node (AVN) and ventricle of the rabbit heart. Cells were held at −40 mV and 5 μM external nifedipine was used to block L-type calcium current (I Ca,L). SignificantI K was observed with pulses to potentials more positive than −30 mV. The steady-state activation curve in both cell types showed maximal activation at between + 10 and + 20 mV. Half-maximal activation ofI K occurred at −4.9 and −4.1 mV with slope factors of 8.3 and 12.4 mV in ventricular and AVN cells, respectively. Using pulses of increasing duration, significantI K tails after repolarisation from + 40 mV were observed with pulses of 20 ms and increased with pulses up to 100–120 ms in both cell types. Pulses of longer duration did not activate furtherI K and this suggested that only the rapid component ofI K, calledI Kr, was present in either cell type. Moreover,I K tails after pulses to all potentials were blocked completely by E-4031, a selective blocker ofI Kr. The reversal potential ofI K varied with the concentration of external K. Superfusion of AVN cells with medium containing 4, 15 and 40 mM [K+]o resulted in reversal potentials of −81, −56 and −32 mV respectively, which are close to values predicted if theI K channel were highly selective for K. The time constants for deactivation ofI K in ventricle and AVN on return to −40 mV after a 500-ms activating pulse to + 60 mV were 480 ms and 230 ms, respectively. The faster deactivation ofI K in AVN cells was a distinguishing feature and suggests that there may be differences in theI Kr channel protein between ventricular and AVN cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253834
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Characteristics of the delayed rectifier K current compared in myocytes isolated from the atrioventricular node and ventricle of the rabbit heart (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 713-722 
    Details
    ISSN: 1432-2013
    Keywords: Key words Atrioventricular node ; Myocyte ; Ventricle ; Delayed rectifier potassium current (Ik) ; E-4031
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The delayed rectifier potassium current (I K) is known to be important in action potential repolarisation and may contribute to the diastolic pacemaker depolarisation in pacemaker cells from the heart. In this study, using whole-cell patch clamp, we investigated the characteristics of I K in morphologically normal cells from the atrioventricular node (AVN) and ventricle of the rabbit heart. Cells were held at −40 mV and 5 μM external nifedipine was used to block L-type calcium current (I Ca,L). Significant I K was observed with pulses to potentials more positive than −30 mV. The steady-state activation curve in both cell types showed maximal activation at between + 10 and + 20 mV. Half-maximal activation of I K occurred at −4.9 and −4.1 mV with slope factors of 8.3 and 12.4 mV in ventricular and AVN cells, respectively. Using pulses of increasing duration, significant I K tails after repolarisation from + 40 mV were observed with pulses of 20 ms and increased with pulses up to 100–120 ms in both cell types. Pulses of longer duration did not activate further I K and this suggested that only the rapid component of I K, called I Kr, was present in either cell type. Moreover, I K tails after pulses to all potentials were blocked completely by E-4031, a selective blocker of I Kr. The reversal potential of I K varied with the concentration of external K. Superfusion of AVN cells with medium containing 4, 15 and 40 mM [K+]o resulted in reversal potentials of −81, −56 and −32 mV, respectively, which are close to values predicted if the I K channel were highly selective for K. The time constants for deactivation of I K in ventricle and AVN on return to −40 mV after a 500-ms activating pulse to + 60 mV were 480 ms and 230 ms, respectively. The faster deactivation of I K in AVN cells was a distinguishing feature and suggests that there may be differences in the I Kr channel protein between ventricular and AVN cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050056
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Sexual dimorphism in north American hawks I. Sex organsAided by grants from the National Research Council, Committee for Research on Problems of Sex, grants administered by Prof. Emil Witschi. (1937)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 321-349 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the gonads of the marsh hawk, Circus hudsonius, Cooper's hawk, Accipiter cooperi, and the red-tailed hawk, Buteo borealis borealis has been investigated. The occurrence and relatively long persistence of the cortex on both testes of the marsh hawk is evidence of bilateral amphisexuality in this form. The embryonic condition of the ovaries is related to the degree of asymmetry in the adult organs. Nearly symmetrical, paired ovaries were found in three species and varying amounts of reduction of the right ovary in all others.The disappearance of the right oviduct in the ontogeny of the female red-tailed hawk and the occurrence of accessory gonad tissue in male embryos of the same species are described and figured. The extent of reduction of the right ovary of eleven species is described, figured and classified. The following species are listed in the above order of classification: Circus hudsonius, Accipiter cooperi, Accipiter velox velox, Accipiter atricapillus atricapillus, Falco sparverius sparverius, Aquila chrysaëtos canadensis, Buteo borealis borealis, Buteo lineatus lineatus, Buteo lagopus sancti-johannis, Cathartes aura septentrionalis, Buteo platypterus platypterus.It is concluded that two ways by which organs may disappear are realized in the right ovary and oviduct of the hawks. (1) by failure of an embryonic inductor in the case of the ovary, and (2) in the right oviduct by secondary atrophy of an originally well-developed embryonic structure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050610206
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Sex chromatin and idiograms from rats exhibiting anomalies of the reproductive organs (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 153 (1965), S. 85-91 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Certain anomalous conditions associated with the reproductive organs have arisen in a line of King-Holtzmann hybrid rats maintained in our laboratory. These are sterile pseudohermaphroditic males in which the entire reproductive tract except the testes is missing; apparent males demonstrating an ectopic inguinal ring and testis on one or both sides; and sterile males with descended scrotal testes. The procedure developed by Moore ('55) for staining sex chromatin was applied to cells from liver, spinal cord, testis, and parotid gland of rats. A sex difference is clearly shown, however, only with the liver cells. Ford and Woollam's ('64) sequence for demonstrating mammalian chromosomes renders positive results on bone marrow cells. This method applied to liver and testis yields unsatisfactory results.Examination of idiograms and sex chromatin bodies from animals exhibiting the conditions outlined above leads to the following conclusions: (1) all abnormal animals studied are genetic males; and (2) the pseudohermaphrodites, though genetically male, exhibit a pattern of differentiation of chromosomes during the metaphase plate stage resembling that in the female.Similarities between certain anatomic and physiologic factors exhibited in pseudohermaphroditic rats and those present in “testicular feminization” in man are discussed. Male rats exhibiting an ectopic inguinal ring and testis and sterile males with descended scrotal testes also may have their counterpart in man.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091530110
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Germ cell migration in relation to asymmetry in the sex glands of hawksAided by grants from the National Research Council, Committee for Research in Problems of Sex. (1940)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 76 (1940), S. 329-342 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1090760310
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of exogenous gangliosides on human neural cell division (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 113 (1982), S. 186-191 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Human neural cells in exponential growth phase were transferred to a serum-free medium and maintained for 72 hr without any detectable loss in viability. The two normal fetal cell lines (CHI and CHII) showed a serum-dependent cell proliferation, but the glioblastoma multiforme cells (12-18) were able to continue proliferating in this totally synthetic medium. The incorporation of [3H] thymidine into the acid-precipitable fraction of both normal and neoplastic human neural cells was assayed in the presence and the absence of exogenous gangliosides by a convenient new method. In serum-free medium, gangliosides (50 μM) inhibited the thymidine incorporation into the normal fetal cells within 24 hr and, in serum containing medium, reduced their proliferation within 48 hr. No such effects were detectable in the glioma cells. The inhibition of thymidine incorporation in the normal cells was reversible upon removal of the gangliosides. These results indicate a role of gangliosides in the postmitotic phase of normal human neural cells resulting in the regulation of cell proliferation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041130128
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Insulin-like growth factor 1, insulin, and progesterone induce early and late increases in Xenopus oocyte sn-1, 2-diacylglycerol levels before meiotic cell division (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 149 (1991), S. 252-259 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: After a 3 to 6 hour incubation, addition of progesterone (the most effective), insulin-like growth factor 1 (IGF-1; the second most effective), or insulin induces meiotic cell division in Xenopus oocytes. Measurement of an endogenous activator of protein kinase C, sn-1,2-diacylglycerol (DAG), by an enzymatic method recording mass demonstrates that all three hormones alter DAG levels. Five seconds after addition, only progesterone transiently reduces DAG levels by about 25%. At 15 minutes after addition, all three hormones produce a peak of DAG (115% to 160% of control values), with the more effective hormones producing a larger increase in DAG. Insulin produces the smallest DAG increase, but the DAG release is longer lasting. Finally, all three hormones induce a second peak in DAG levels just before white spot appearance (at 0.85 GVBD50, where 1.0 GVBD50 is when 50% of the cells have divided). With these data and since an activator of protein kinase C, a phorbol ester, has been found to induce meiosis, the kinase may play a role in early proliferative events at the plasma membrane and in late events at the nucleus.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041490211
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