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Characteristics of Ca Currents in Rabbit Basilar Arterial Smooth Muscle Cells

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Authors
So, Insuk; Kang, Tong Mook; Kim, Ki Whan
Issue Date
1994-09
Publisher
Seoul National University College of Medicine
Citation
Seoul J Med, Vol.35 No.3, pp. 169-182
Keywords
L-type Ca currentsbasilar arterypatch clampwindow current
Abstract
In order to determine the exact nature of Ca channels involved in various
cerebrovascular contractile behaviour including vasospasm, we performed experiments
to identify and characterize the types of Ca channels in rabbit basilar arterial
smooth muscle cells by using kinetic and pharmacologic tools. Sngle smooth muscle
cells were enzymatically isolated from rabbit basilar artery. Single cells were voltageclamped,
and membrane currents were recorded using the whole-cell configuration of
patch clamp technique. The measured cell capacitance (Cm) was 19.2 ± 0.65 pF ( n 21)
and input resistance (Rmpu, ) was 2.04 ± 0.12 Gn(n 12), These passive membame properties
are similar to other cerebraovascular smooth muscle cells. Inward Ca2
' -channel
current was recorded. Replacement of external Ca2+( 2 mM) with Ba" (10 mM) increased
the amplitude of the current and did not shift the I-V relationship for lBa in comparison
with that for Ie.. Changing the holding potential from -SO to -40 mV decreased the
current amplitude but did not shift the voltage dependence. No detectable low-threshold,
rapid inactivating inward current was observed. Steady-state activation and inactivation
curves for lea(V, 210c') -4.4 mV; V, 2(inac,) -22.3 mV) and lBa(v, 2(oc') -7.5 mV; VI 2
{Inact } -20.5 mV) were determined. The theoritical 'window current's amplitude was calculated
for lea and lBa• Calcium channel current was almost completely inhibited by l,uM
nicardipine and enhanced by Bay K 8644, suggesting this is carried by 'L-type' but not
by 'T-type' calcium channel. Bay K 8644 significantly shifted activation curve to the negative
potential. Both 8-br-cAMPW.l ~ 1 mM) and 8-br-cGMP( 0.1 ~ 1 mM), a membrane
permeable cyclic nucleotides, decreased the current amplitude. From the above
results, it is suggested that only 'L-type' Ca-current(ICa_d exists in rabbit basilar arterial
smooth muscle cells.
ISSN
0582-6802
Language
English
URI
http://hdl.handle.net/10371/7345
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College of Medicine/School of Medicine (의과대학/대학원)Dept. of Medicine (의학과)The Seoul Journal of MedicineThe Seoul Journal of Medicine Vol. 35 No.3 (1994)
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