Calcium-activated potassium-channels in mammalian eggs
dc.contributor.author
Georgiou, Panayiotis Paulou
en
dc.date.accessioned
2018-05-14T10:13:01Z
dc.date.available
2018-05-14T10:13:01Z
dc.date.issued
1985
dc.description.abstract
en
dc.description.abstract
Intracellular microelectrode recordings from zonafree hamster eggs revealed a mean value for the
membrane potential of -34+9mV (mean ± SD, n=36) and a
mean value for the input resistance of 290±170MΩ.(mean ±
SD) .
en
dc.description.abstract
Ionophoretic injection of calcium ions into a
hamster egg caused a marked membrane hyperpolarization
(mean ± SD = 27±9mV, n=63) which was associated with a
large reduction in the egg input resistance (viz. from
140±94MΩ prior to the injection to 40±24MΩ at the peak
of the response, n=63). The estimated reversal
potential of the calcium-evoked hyperpolarization was
found to be -69±11mV (mean ± SD,n=63). The mean slope
of the relation between the reversal potential and
log₁₀[ᴷ⁺]ₒ was 50mV in good agreement with the value
predicted by the Nernst equation for a rise in
conductance primarily selective for potassium ions. In
addition the reversal potential was unaffected by about
a tenfold reduction in the concentration of external
chloride. It is concluded that the calcium-evoked
hyperpolarization was caused by the opening of membrane
potassium channels that are activated by an increase in
the intracellular concentration of ionized free
calcium.
en
dc.description.abstract
The duration of the calcium-evoked response was
markedly extended in the presence of ImM external
lanthanum or 20mM calcium or by external application of
0.2-2mM 2,4,dinitrophenol.
en
dc.description.abstract
Double microelectrode experiments identified the
presence of an impalement leak artifact which might
cause an underestimate of the true membrane potential
and input resistance. Evidence is also presented for a
second type of artifact, namely the generation of a
leak conductance pathway during the passage of large
depolarizing current pulses (>10nA, 1 sec) used for the
ionophoretic injection of calcium into cells.
en
dc.identifier.uri
http://hdl.handle.net/1842/29774
dc.publisher
The University of Edinburgh
en
dc.relation.ispartof
Annexe Thesis Digitisation Project 2018 Block 18
en
dc.relation.isreferencedby
Already catalogued
en
dc.title
Calcium-activated potassium-channels in mammalian eggs
en
dc.type
Thesis or Dissertation
en
dc.type.qualificationlevel
Doctoral
en
dc.type.qualificationname
PhD Doctor of Philosophy
en
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