Pinacidil activates the ATP-sensitive K+ channel in inside-out and cell-attached patch membranes of guinea-pig ventricular myocytes

1990 ◽  
Vol 415 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Zheng Fan ◽  
Keiko Nakayama ◽  
Masayasu Hiraoka
Keyword(s):  
Guinea Pig ◽  
Ventricular Myocytes ◽  
K Channel ◽  
Inside Out

Calmodulin reverses rundown of L-type Ca2+ channels in guinea pig ventricular myocytes

2004 ◽  
Vol 287 (6) ◽  
pp. C1717-C1724 ◽  
Author(s):  
Jian-Jun Xu ◽  
Li-Ying Hao ◽  
Asako Kameyama ◽  
Masaki Kameyama
Keyword(s):  
Protein Kinase ◽  
Guinea Pig ◽  
Kinase Inhibitors ◽  
Ventricular Myocytes ◽  
Protein Kinase Inhibitors ◽  
Channel Activity ◽  
Dependent Protein ◽  
Dose Dependent ◽  
Inside Out ◽  
Ca2 Channels

Calmodulin (CaM) is implicated in regulation of Ca2+ channels as a Ca2+ sensor. The effect of CaM on rundown of L-type Ca2+ channels in inside-out patch form was investigated in guinea pig ventricular myocytes. Ca2+ channel activity disappeared within 1–3 min and did not reappear when the patch was excised and exposed to an artificial intracellular solution. However, application of CaM (0.03, 0.3, 3 μM) + 3 mM ATP to the intracellular solution within 1 min after patch excision resulted in dose-dependent activation of channel activity. Channel activity averaged 11.2%, 94.7%, and 292.9%, respectively, of that in cell-attached mode. Channel activity in inside-out patch mode was induced by CaM + ATP at nanomolar Ca2+ concentrations ([Ca2+]); however, increase to micromolar [Ca2+] rapidly inactivated the channel activity induced, revealing that the effect of CaM on the channel was Ca2+ dependent. At the 2nd, 4th, 6th, 8th, and 10th minutes after patch excision, CaM (0.75 μM) + ATP induced Ca2+ channel activity to 150%, 100%, 96.9%, 29.3%, and 16.6%, respectively, revealing a time-dependent action of CaM on the channel. CaM added with adenosine 5′-(β,γ-imido)triphosphate (AMP-PNP) also induced channel activity, although with much lower potency and shorter duration. Protein kinase inhibitors KN-62, CaM-dependent protein kinase (CaMK)II 281-309, autocamtide-related CaMKII inhibitor peptide, and K252a (each 1–10 μM) did not block the effect of CaM, indicating that the effect of CaM on the Ca2+ channel was phosphorylation independent. Neither CaM nor ATP alone induced Ca2+ channel activity, showing a cooperative effect of CaM and ATP on the Ca2+ channel. These results suggest that CaM is a crucial regulatory factor of Ca2+ channel basal activity.

5-hydroxydecanoate inhibits ATP-sensitive K+ channel currents in guinea-pig single ventricular myocytes

1992 ◽  
Vol 220 (1) ◽  
pp. 35-41 ◽  
Author(s):  
Tatsuto Notsu ◽  
Kiyokazu Ohhashi ◽  
Isao Tanaka ◽  
Hiroshi Ishikawa ◽  
Takeshi Niho ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Ventricular Myocytes ◽  
K Channel ◽  
Single Ventricular Myocytes ◽  
Channel Currents

Regulation of KATP channels by P2Ypurinoceptors coupled to PIP2 metabolism in guinea pig ventricular cells

2002 ◽  
Vol 282 (2) ◽  
pp. H757-H765 ◽  
Author(s):  
Naoya Oketani ◽  
Masafumi Kakei ◽  
Kotaro Ichinari ◽  
Midori Okamura ◽  
Akihiro Miyamura ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Ventricular Myocytes ◽  
Katp Channels ◽  
Extracellular Atp ◽  
Channel Activity ◽  
Channel Current ◽  
Channel Inhibition ◽  
Ventricular Cells ◽  
Inside Out ◽  
Stimulation Of

We used patch-clamp techniques to elucidate the regulatory mechanisms of ATP-sensitive K+(KATP) channels by stimulation of P2purinoceptors in guinea pig ventricular myocytes. Extracellular ATP at 0.1 mM transiently inhibited by 90.5 ± 5.0% the whole cell KATP channel current evoked by a reduction in intracellular ATP concentration to 0.5 mM and exposure to 30 μM pinacidil. ADP and AMP (both 1 mM) also decreased the current by 42.8 ± 9.3% and 9.4 ± 4.8%, respectively, but adenosine did not, even at 10 mM. ATP-induced channel inhibition was hardly observed in the presence of 0.2 mM suramin, 0.2 mM guanosine 5'- O-(2-thiodiphosphate), or 0.1 mM compound 48/80, whereas it was not influenced by the presence of 0.1 μM staurosporine or 10 mM 1,2-bis(2-aminophenoxy)ethane- N,N,N′,N′-tetraacetic acid in the pipette. In the presence of 10 μM wortmannin or the absence of ATP in the cytosol, the ATP-induced channel inhibition was irreversible. Phosphatidylinositol 4,5-bisphosphate (PIP2) at 0.1 mM in the outside-out patch pipette prevented ATP-induced channel inhibition. The half-maximal internal ATP concentrations for inhibition of channel activity determined in inside-out membrane patches were 13.8 μM in the presence and 1.12 mM in the absence of 0.1 mM ATP at the external side. It is concluded that activity of KATP channels is modulated by extracellular ATP by a mechanism involving P2Y purinoceptors coupled to GTP-binding proteins associated with reduction of the sarcolemmal PIP2 concentration via stimulation of phospholipase C.

Permeability of time-dependent K+ channel in guinea pig ventricular myocytes to Cs+, Na+, NH4+, and Rb+

1990 ◽  
Vol 259 (5) ◽  
pp. H1448-H1454 ◽  
Author(s):  
R. W. Hadley ◽  
J. R. Hume
Keyword(s):  
Guinea Pig ◽  
Ventricular Myocytes ◽  
Reversal Potential ◽  
Outward Current ◽  
Time Dependent ◽  
K Channel ◽  
Delayed Rectifier ◽  
Patch Clamp Technique ◽  
Whole Cell Patch Clamp ◽  
Outward Currents

Currents through time-dependent K+ channels (also referred to as IK or the delayed rectifier) were studied with the whole cell patch-clamp technique in isolated guinea pig ventricular myocytes. IK measurements were restricted to the examination of deactivation tail currents. Substitution of various monovalent cations for external K+ produced shifts of the reversal potential of IK. These shifts were used to calculate permeability ratios relative to K+. The permeability sequence for the IK channels was K+ = Rb+ greater than NH4+ = Cs+ greater than Na+. Time-dependent outward currents were also examined when the myocytes were dialyzed with Cs+ instead of K+. A sizeable time-dependent outward current, quite similar to that seen with K+ dialysis, was demonstrated. This current was primarily carried by intracellular Cs+, as the reversal potential of the current shifted 46 mV per 10-fold change of external Cs+ concentration. The significance of Cs+ permeation through IK channels is discussed with respect to the common use of Cs+ in isolating other currents.

scholarly journals Mechanism for reactivation of the ATP-sensitive K+ channel by MgATP complexes in guinea-pig ventricular myocytes.

1994 ◽  
Vol 479 (1) ◽  
pp. 95-107 ◽  
Author(s):  
T Furukawa ◽  
L Virág ◽  
N Furukawa ◽  
T Sawanobori ◽  
M Hiraoka
Keyword(s):  
Guinea Pig ◽  
Ventricular Myocytes ◽  
K Channel

scholarly journals Action of nicorandil on ATP-sensitive K+ channel in guinea-pig ventricular myocytes

1991 ◽  
Vol 103 (3) ◽  
pp. 1641-1648 ◽  
Author(s):  
Keiko Nakayama ◽  
Zheng Fan ◽  
Fumiaki Marumo ◽  
Tohru Sawanobori ◽  
Masayasu Hiraoka
Keyword(s):  
Guinea Pig ◽  
Ventricular Myocytes ◽  
K Channel
Sign in / Sign up

Export Citation Format

Share Document