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  • 1
    Electronic Resource
    Electronic Resource
    Acetylcholine and adenosine activate the G protein-gated muscarinic K+channel in ferret ventricular myocytes (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 610-617 
    Details
    ISSN: 1432-1912
    Keywords: Key words Ferret ; Ventricular myocytes ; Acetylcholine ; Adenosine ; Muscarinic K+ channel ; G protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The properties of the K+ channel activated by acetylcholine (ACh) and adenosine (Ado) were examined in single ferret ventricular myocytes using patch-clamp techniques. In the whole-cell configuration, ACh and Ado induced an inwardly rectifying K+ current and shortened the action potential duration. The effect of ACh was blocked by atropine, while the Ado effect was interrupted by 8-cyclopentyl,1,2-dipropyl xanthine, a specific Ado A1 receptor antagonist. In cell-attached recordings, ACh and Ado added to the pipette solution activated a single population of inwardly rectifying K+ channels, distinct from the i K1 channel. The channel had a slope conductance of ∼40 pS in symmetrical 150 mM K+ solutions and a mean open time of 0.8 ms. Excision of the patch into the inside-out patch configuration in guanosine triphosphate (GTP)-free solution abolished the channel activity. The channel was reversibly reactivated by adding GTP to the intracellular side of the patch. GTPγS activated the channel irreversibly. When the inside-out patch was treated with the A protomer of pertussis toxin (PTX), intracellular GTP no longer activated the K+ channel. The results show that ferret ventricular myocytes possess a K+ channel activated by both muscarinic and Ado A1 receptors. Its electrophysiological properties and the gating by a PTX-sensitive G protein in a membrane-delimited fashion are identical with those of the muscarinic K+ channels in nodal and atrial tissues of other species. In conclusion, the G protein-gated muscarinic K+ channel is expressed in ferret ventricular myocardium and may underlie the direct negative inotropism of ACh and Ado in this tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00170160
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Acetylcholine and adenosine activate the G protein-gated muscarinic K+ channel in ferret ventricular myocytes (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 610-617 
    Details
    ISSN: 1432-1912
    Keywords: Ferret ; Ventricular myocytes ; Acetylcholine ; Adenosine ; Muscarinic K+ ; channel ; G protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The properties of the K+ channel activated by acetylcholine (ACh) and adenosine (Ado) were examined in single ferret ventricular myocytes using patch-clamp techniques. In the whole-cell configuration, ACh and Ado induced an inwardly rectifying K+ current and shortened the action potential duration. The effect of ACh was blocked by atropine, while the Ado effect was interrupted by 8-cyclopenty1,1,2-dipropyl xanthine, a specific Ado A1 receptor antagonist. In cell-attached recordings, ACh and Ado added to the pipette solution activated a single population of inwardly rectifying K+ channels, distinct from the i K1 channel. The channel had a slope conductance of ∼ 40 pS in symmetrical 150 mM K+ solutions and a mean open time of 0.8 ms. Excision of the patch into the inside-out patch configuration in guanosine triphosphate (GTP)-free solution abolished the channel activity. The channel was reversibly reactivated by adding GTP to the intracellular side of the patch. GTPγS activated the channel irreversibly. When the inside-out patch was treated with the A protomer of pertussis toxin (PTX), intracellular GTP no longer activated the K+ channel. The results show that ferret ventricular myocytes possess a K+ channel activated by both muscarinic and Ado A1 receptors. Its electrophysiological properties and the gating by a PTX-sensitive G protein in a membrane-delimited fashion are identical with those of the muscarinic K+ channels in nodal and atrial tissues of other species. In conclusion, the G protein-gated muscarinic K+ channel is expressed in ferret ventricular myocardium and may underlie the direct negative inotropism of ACh and Ado in this tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00170160
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Idea to measure diastolic arterial pressure by volume oscillometric method in human fingers (1986)
    Springer
    Medical & biological engineering & computing 24 (1986), S. 549-554 
    Details
    ISSN: 1741-0444
    Keywords: Finger arterial pressure ; Indirect diastolic pressure ; Photoelectric plethysmography ; Volume oscillometric method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443975
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Vibration technique for indirect measurement of diastolic arterial pressure in human fingers (1989)
    Springer
    Medical & biological engineering & computing 27 (1989), S. 130-136 
    Details
    ISSN: 1741-0444
    Keywords: Diastolic pressure ; Finger arterial pressure ; Indirect sphygmomanometry ; Photoelectric plethysmography ; Pressure/volume relation ; Vibration method ; Volume oscillometric method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Diastolic pressure Pd was indirectly measured by vibrating a finger artery with a 10 Hz sinusoidal pressure variation during a gradual increase (or decrease) in occlusive cuff pressure Pc. Pulsatile arterial volume changes on which sinusoidal variations are superimposed were detected by a transmitted infra-red photoelectric plethysmograph (TIPP). It is known that volume change in an artery shows a maximum amplitude at the transmural pressure Pt level equal to 0 mm Hg due to the nonlinear viscoelastic properties of the arterial wall. For the same reason, the amplitude of the sinusoidal volume variation reached its maximum at the end-diastolic phase, when Pc was controlled to be exactly equal to Pd. The indirect Pd values determined from Pc were compared with those simultaneously measured by a direct method in rabbit forelegs and by the volume-compensation method in human fingers. Using the principle of the volume oscillometric method systolic and mean pressures were also determined by this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446221
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Noninvasive measurement of arterial elasticity in various human limbs (1988)
    Springer
    Medical & biological engineering & computing 26 (1988), S. 641-646 
    Details
    ISSN: 1741-0444
    Keywords: Admittance plethysmography ; Arterial compliance ; Human limb ; Noninvasive measurement ; Volume elastic modulus ; Volume oscillometric method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Arterial elasticity expressed by such indices as volume elastic modulus Ev and compliance Ca were noninvasively measured in various human limb segments; the upper arms, forearms, fingers, thighs, calves and toes. These indices are defined, respectively, as $$E_v = \Delta P/(\Delta V/\bar V_a )$$ and Ca=ΔV/ΔP, where ΔP is pulse pressure, $$\bar V_a $$ mean arterial volume and ΔV its pulsatile variation. ΔP was calculated from systolic Pas and mean Pam arterial pressures determined by volume oscillometric sphygmomanometry using the following equation: $$\Delta P = 3(P_{as} - P_{am} )/2\bar V_a $$ and the ΔV were detected by electrical admittance plethysmography at various transmural pressure Pt levels controlled by a compression cuff. The values obtained in these limb segments were compared with each other at Pt levels 0,30 and 60 mm Hg and the differences between them were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447504
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    Paper (German National Licenses)
    Fulltext
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