scholarly journals Transient outward current in adult rat supraoptic neurones with slice patch-clamp technique: inhibition by angiotensin II.

1995 ◽  
Vol 485 (1) ◽  
pp. 87-96 ◽  
Author(s):  
T Nagatomo ◽  
K Inenaga ◽  
H Yamashita
Keyword(s):  
Angiotensin Ii ◽  
Patch Clamp ◽  
Outward Current ◽  
Transient Outward Current ◽  
Patch Clamp Technique ◽  
Adult Rat ◽  
Clamp Technique

Characterizations of the Urate Transporter, GLUT9, and Its Potent Inhibitors by Patch-Clamp Technique

2020 ◽  
pp. 247255522094950
Author(s):  
Yanyu Chen ◽  
Zean Zhao ◽  
Yongmei Li ◽  
Lu Li ◽  
Yu Jiang ◽  
...  
Keyword(s):  
Uric Acid ◽  
Patch Clamp ◽  
Glucose Transporter ◽  
Cell Model ◽  
Outward Current ◽  
External Solution ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Clamp Technique ◽  
Induced Currents

Glucose transporter 9 (GLUT9), which transports urate in an electrogenic and voltage-dependent manner, plays an important role in the maintenance of normal blood uric acid/urate levels. In the present study, we established a cell model based on the single-electrode patch-clamp technique for characterization of GLUT9 and explored the inhibitory effects of benzobromarone (BM) and probenecid (PB) on urate-induced currents in mouse GLUT9a (mGLUT9a)–expressing HEK-293T cells. The results showed that uric acid, rather than glucose perfusion, led to a rapid and large outward current by mGLUT9a in dose-, voltage-, and pH-dependent manners. BM prominently and irreversibly inhibited the uric acid–induced currents through mGLUT9a, and PB weakly and reversibly inhibited mGLUT9a. We found that depletion of K+ in the external solution significantly strengthened the blockade of BM on mGLUT9a. In addition, an enhanced inhibitory rate of BM was detected when the pH of the external solution was changed from 7.4 to 5.5, indicating that BM functions optimally in an acidic environment. In conclusion, the combination of the established cell model with patch-clamp techniques first revealed the function properties of GLUT9 inhibitors and may provide potential benefits to the study of GLUT9 inhibitors as antihyperuricemic or antigout agents.

Modulation of the transient outward current in adult rat ventricular myocytes by polyunsaturated fatty acids

1998 ◽  
Vol 274 (2) ◽  
pp. H571-H579 ◽  
Author(s):  
K. Y. Bogdanov ◽  
H. A. Spurgeon ◽  
T. M. Vinogradova ◽  
E. G. Lakatta
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Ventricular Myocytes ◽  
Outward Current ◽  
Transient Outward Current ◽  
Patch Clamp Technique ◽  
Rat Ventricular Myocytes ◽  
Adult Rat ◽  
Low Concentrations ◽  
High Concentrations

With the whole cell patch-clamp technique, we studied the effects of the n-3 and n-6 polyunsaturated fatty acids (PUFAs), linoleic (C18:2n-6), eicosapentaenoic (C20:4n-3), docosahexaenoic (C22:5n-3), and arachidonic (AA; C20:4n-6) acids, on K+ currents in rat ventricular myocytes. At low concentrations (5–10 μM) all PUFAs except AA inhibited, by ∼40%, the transient outward current ( I to) without affecting other K+ currents and markedly prolonged the action potential (AP). AA inhibited I to but also augmented a sustained depolarization-induced outward K+ current ( I sus); the latter effect did not occur in the presence of 4-aminopyridine or with eicosatetraynoic acid, a nonmetabolizable analog of AA. Higher concentrations of PUFAs (20–50 μM) further inhibited I to and also inhibited I sus. Thus, at high concentrations, PUFAs have a nonspecific effect on several K+ channels; at low concentrations, PUFAs preferentially inhibit I to and prolong the AP.

2,4-dinitrophenol acutely inhibits rabbit atrial Ca2+-sensitive Cl- current (ITO2)

2000 ◽  
Vol 78 (10) ◽  
pp. 766-773 ◽  
Author(s):  
J H Ravesloot ◽  
E Rombouts
Keyword(s):  
Patch Clamp ◽  
Outward Current ◽  
Rabbit Heart ◽  
Transient Outward Current ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Atrial Myocytes ◽  
Inhibitory Effects ◽  
Patch Clamp Technique ◽  
Current Increase ◽  
Whole Cell Patch Clamp

We investigated the effects of 2,4-dinitrophenol (DNP), the uncoupler of mitochondrial oxidative phosphorylation, on the Ca2+-sensitive Cl- current component of the transient outward current (ITO2). Amphotericin B perforated-patch, whole-cell patch-clamp technique was employed (35°C) using enzymatically isolated single rabbit atrial myocytes. We defined ITO2 as the amplitude of the 2 mM 4-aminopyridine resistant transient outward current sensitive to anthracene-9-carboxylic acid (A9C). Between +5 and +45 mV, 0.2 mM A9C inhibited ITO2 by ~70% (n = 13). Within 30 s after application of 0.2 mM DNP, both normal ITO2 transients (n = 8) and the ITO2 transients that remained after A9C treatment (n = 8) were inhibited completely. In cells expressing ITO2 (70% of total), DNP also suppressed an A9C-insensitive slow outward current by ~40%, but the holding current at -80 mV was unaffected. There was a ~2 min latency between inhibitory effects of DNP and subsequent membrane current increase, presumably caused by activation of the ATP-sensitive K+ channels (n = 16). We conclude that DNP acutely inhibits ITO2 via a mechanism presumably separate from metabolic inhibition.Key words: patch clamp, rabbit heart, simulated ischemia, calcium-sensitive chloride current.

Inhibition of metabolism abolishes transient outward current in rabbit atrial myocytes

1994 ◽  
Vol 266 (1) ◽  
pp. H182-H190 ◽  
Author(s):  
A. Ogbaghebriel ◽  
A. Shrier
Keyword(s):  
Steady State ◽  
Patch Clamp ◽  
Potassium Current ◽  
Outward Current ◽  
Transient Outward Current ◽  
Atrial Myocytes ◽  
Patch Clamp Technique ◽  
Outward Currents ◽  
Inward Currents ◽  
Inhibition Of Metabolism

Outward currents were measured in single rabbit atrial myocytes using the whole cell configuration of the patch-clamp technique in the presence of tetrodotoxin (5–10 microM) and MnCl2 (2 mM) to block inward currents. Depolarizing voltage-clamp steps from a holding potential of -80 mV elicited a predominant 4-aminopyridine (4-AP)-sensitive transient outward current (Ito). Inhibitors of oxidative metabolism, 2,4-dinitrophenol (DNP; 100 microM) and cyanide (3 mM) abolished Ito and caused a large increase in the steady-state outward current. This steady-state outward current was inhibited by glibenclamide (5 microM), a blocker of the ATP-regulated potassium current (IKATP). In the presence of DNP, glibenclamide (5 microM) not only inhibited IKATP but also partially restored Ito. Absence of ATP from the pipette produced effects on outward currents similar to those induced by DNP or cyanide. We conclude that metabolic inhibition abolishes Ito in rabbit atrial myocytes and suggest that ATP may be required for the activation of the channel.

Ketamine blocks Ca2+-activated K+ channels in rabbit cerebral arterial smooth muscle cells

2003 ◽  
Vol 285 (3) ◽  
pp. H1347-H1355 ◽  
Author(s):  
Jin Han ◽  
Nari Kim ◽  
Hyun Joo ◽  
Euiyong Kim
Keyword(s):  
Smooth Muscle ◽  
Patch Clamp ◽  
Smooth Muscle Cells ◽  
Cerebral Arteries ◽  
Muscle Cells ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Arterial Smooth Muscle ◽  
Clamp Technique ◽  
Arterial Smooth Muscle Cells

Although ketamine and Ca2+-activated K+ (KCa) channels have been implicated in the contractile activity regulation of cerebral arteries, no studies have addressed the specific interactions between ketamine and the KCa channels in cerebral arteries. The purpose of this study was to examine the direct effects of ketamine on KCa channel activities using the patch-clamp technique in single-cell preparations of rabbit middle cerebral arterial smooth muscle. We tested the hypothesis that ketamine modulates the KCa channel activity of the cerebral arterial smooth muscle cells of the rabbit. Vascular myocytes were isolated from rabbit middle cerebral arteries using enzymatic dissociation. Single KCa channel activities of smooth muscle cells from rabbit cerebral arteries were recorded using the patch-clamp technique. In the inside-out patches, ketamine in the micromolar range inhibited channel activity with a half-maximal inhibition of the ketamine conentration value of 83.8 ± 12.9 μM. The Hill coefficient was 1.2 ± 0.3. The slope conductance of the current-voltage relationship was 320.1 ± 2.0 pS between 0 and +60 mV in the presence of ketamine and symmetrical 145 mM K+. Ketamine had little effect on either the voltage-dependency or open- and closed-time histograms of KCa channel. The present study clearly demonstrates that ketamine inhibits KCa channel activities in rabbit middle cerebral arterial smooth muscle cells. This inhibition of KCa channels may represent a mechanism for ketamine-induced cerebral vasoconstriction.

Ion channel activities of cultured rat mesangial cells

1991 ◽  
Vol 261 (5) ◽  
pp. F808-F814 ◽  
Author(s):  
H. Matsunaga ◽  
N. Yamashita ◽  
Y. Miyajima ◽  
T. Okuda ◽  
H. Chang ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Ion Channels ◽  
Patch Clamp ◽  
Ion Channel ◽  
Arginine Vasopressin ◽  
Mesangial Cells ◽  
Cation Channel ◽  
K Channel ◽  
Patch Clamp Technique ◽  
Inside Out

We used the patch-clamp technique to clarify the nature of ion channels in renal mesangial cells in culture. In the cell-attached mode most patches were silent in the absence of agonists. In some patches a 25-pS nonselective channel was observed. This 25-pS cation channel was consistently observed in inside-out patches, and it was activated by intracellular Ca2+. Excised patch experiments also revealed the existence of a 40-pS K+ channel, which was activated by intracellular Ca2+. This 40-pS K+ channel was observed infrequently in the cell-attached mode. The activities of both channels were increased by arginine vasopressin or angiotensin II, resulting from an increase in intracellular Ca2+ concentration.

Sign in / Sign up

Export Citation Format

Share Document