Abstract
With the use of the patch-clamp technique, five kinds of stretch- activated (SA) ion channels were identified on the basis of their single- channel conductances and ion selectivities in cultured chick ventricular myocytes. Because a high-conductance K+- selective channel predominated among these channels, we concentrated on characterizing its properties mostly using excised inside-out patches. With 145 mM KCl solution in the pipette and the bath, the channel had a conductance of 199.8 ± 8.2 pS (n = 22). The ion selectivities among K+, Na+, Ca2+, and Cl- as estimated from their permeability ratios were P(Na)/P(K) = 0.03, P(Ca)/P(K) = 0.025, and P(Cl)/P(K) = 0.026. The probability of the channel being open (P(o)) increased with the Ca2+ concentration in the bath ([Ca2+](b); dissociation constant K(d) = 0.51 μM at +30 mV) and membrane potential (voltage at half-maximal P(o) = 39.4 mV at 0.35 μM [Ca2+](b)). The channel was blocked by gadolinium, tetraethylammonium, and charybdotoxin from the extracellular surface and, consequently, was identified as a Ca2+-activated K+ (K(Ca)) channel type. The channel was also reversibly activated by ATP applied to the intracellular surface (K(d) = 0.74 mM at 0.10 μM [Ca2+](b) at +30 mV). From these data taken together, we concluded that the channel is a new type of K(Ca) channel that could be designated as an 'SA K(Ca,ATP) channel.' To our knowledge, this is the first report of K(Ca) channel in heart cells.
| Original language | English |
|---|---|
| Journal | American Journal of Physiology - Heart and Circulatory Physiology |
| Volume | 276 |
| Issue number | 6 45-6 |
| Publication status | Published - Jun 1999 |
| Externally published | Yes |
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Keywords
- Adenosine 5'-triphosphate-activated channel
- Calcium-activated potassium channel
- Patch clamp
- Stretch-activated channel
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
Cite this
Characterization of a newly found stretch-activated K(Ca,ATP) channel in cultured chick ventricular myocytes. / Kawakubo, Takashi; Naruse, Keiji; Matsubara, Tatsuaki; Hotta, Nigishi; Sokabe, Masahiro.
In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 276, No. 6 45-6, 06.1999.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Characterization of a newly found stretch-activated K(Ca,ATP) channel in cultured chick ventricular myocytes
AU - Kawakubo, Takashi
AU - Naruse, Keiji
AU - Matsubara, Tatsuaki
AU - Hotta, Nigishi
AU - Sokabe, Masahiro
PY - 1999/6
Y1 - 1999/6
N2 - With the use of the patch-clamp technique, five kinds of stretch- activated (SA) ion channels were identified on the basis of their single- channel conductances and ion selectivities in cultured chick ventricular myocytes. Because a high-conductance K+- selective channel predominated among these channels, we concentrated on characterizing its properties mostly using excised inside-out patches. With 145 mM KCl solution in the pipette and the bath, the channel had a conductance of 199.8 ± 8.2 pS (n = 22). The ion selectivities among K+, Na+, Ca2+, and Cl- as estimated from their permeability ratios were P(Na)/P(K) = 0.03, P(Ca)/P(K) = 0.025, and P(Cl)/P(K) = 0.026. The probability of the channel being open (P(o)) increased with the Ca2+ concentration in the bath ([Ca2+](b); dissociation constant K(d) = 0.51 μM at +30 mV) and membrane potential (voltage at half-maximal P(o) = 39.4 mV at 0.35 μM [Ca2+](b)). The channel was blocked by gadolinium, tetraethylammonium, and charybdotoxin from the extracellular surface and, consequently, was identified as a Ca2+-activated K+ (K(Ca)) channel type. The channel was also reversibly activated by ATP applied to the intracellular surface (K(d) = 0.74 mM at 0.10 μM [Ca2+](b) at +30 mV). From these data taken together, we concluded that the channel is a new type of K(Ca) channel that could be designated as an 'SA K(Ca,ATP) channel.' To our knowledge, this is the first report of K(Ca) channel in heart cells.
AB - With the use of the patch-clamp technique, five kinds of stretch- activated (SA) ion channels were identified on the basis of their single- channel conductances and ion selectivities in cultured chick ventricular myocytes. Because a high-conductance K+- selective channel predominated among these channels, we concentrated on characterizing its properties mostly using excised inside-out patches. With 145 mM KCl solution in the pipette and the bath, the channel had a conductance of 199.8 ± 8.2 pS (n = 22). The ion selectivities among K+, Na+, Ca2+, and Cl- as estimated from their permeability ratios were P(Na)/P(K) = 0.03, P(Ca)/P(K) = 0.025, and P(Cl)/P(K) = 0.026. The probability of the channel being open (P(o)) increased with the Ca2+ concentration in the bath ([Ca2+](b); dissociation constant K(d) = 0.51 μM at +30 mV) and membrane potential (voltage at half-maximal P(o) = 39.4 mV at 0.35 μM [Ca2+](b)). The channel was blocked by gadolinium, tetraethylammonium, and charybdotoxin from the extracellular surface and, consequently, was identified as a Ca2+-activated K+ (K(Ca)) channel type. The channel was also reversibly activated by ATP applied to the intracellular surface (K(d) = 0.74 mM at 0.10 μM [Ca2+](b) at +30 mV). From these data taken together, we concluded that the channel is a new type of K(Ca) channel that could be designated as an 'SA K(Ca,ATP) channel.' To our knowledge, this is the first report of K(Ca) channel in heart cells.
KW - Adenosine 5'-triphosphate-activated channel
KW - Calcium-activated potassium channel
KW - Patch clamp
KW - Stretch-activated channel
UR - http://www.scopus.com/inward/record.url?scp=0032996632&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032996632&partnerID=8YFLogxK
M3 - Article
C2 - 10362660
AN - SCOPUS:0032996632
VL - 276
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0002-9513
IS - 6 45-6
ER -