scholarly journals New cardiotonic agents which decrease the delayed rectifier and/or the inward-rectifying potassium current.

1991 ◽  
Vol 55 ◽  
pp. 43
Author(s):  
Toshihiko Iijima
Keyword(s):  
Potassium Current ◽  
Delayed Rectifier ◽  
Cardiotonic Agents

scholarly journals Excavatolide-B Enhances Contextual Memory Retrieval via Repressing the Delayed Rectifier Potassium Current in the Hippocampus

Marine Drugs ◽  
2018 ◽  
Vol 16 (11) ◽  
pp. 405 ◽  
Author(s):  
Irene Huang ◽  
Yu-Luan Hsu ◽  
Chien-Chang Chen ◽  
Mei-Fang Chen ◽  
Zhi-Hong Wen ◽  
...  
Keyword(s):  
Memory Retrieval ◽  
Potassium Current ◽  
Memory Function ◽  
Long Term Potentiation ◽  
Autism Spectrum ◽  
Absence Epilepsy ◽  
Delayed Rectifier ◽  
Contextual Memory ◽  
Term Potentiation ◽  
Delayed Rectifier Potassium Current

Memory retrieval dysfunction is a symptom of schizophrenia, autism spectrum disorder (ASD), and absence epilepsy (AE), as well as an early sign of Alzheimer’s disease. To date, few drugs have been reported to enhance memory retrieval. Here, we found that a coral-derived natural product, excavatolide-B (Exc-B), enhances contextual memory retrieval in both wild-type and Cav3.2−/− mice via repressing the delayed rectifier potassium current, thus lowering the threshold for action potential initiation and enhancing induction of long-term potentiation (LTP). The human CACNA1H gene encodes a T-type calcium channel (Cav3.2), and its mutation is associated with schizophrenia, ASD, and AE, which are all characterized by abnormal memory function. Our previous publication demonstrated that Cav3.2−/− mice exhibit impaired contextual-associated memory retrieval, whilst their retrieval of spatial memory and auditory cued memory remain intact. The effect of Exc-B on enhancing the retrieval of context-associated memory provides a hope for novel drug development.

scholarly journals Electrophysiological Properties of Inferior Olive Neurons: A Compartmental Model

1999 ◽  
Vol 82 (2) ◽  
pp. 804-817 ◽  
Author(s):  
Nicolas Schweighofer ◽  
Kenji Doya ◽  
Mitsuo Kawato
Keyword(s):  
Calcium Current ◽  
Potassium Current ◽  
Inferior Olive ◽  
Sodium Current ◽  
Electrical Coupling ◽  
Biophysical Model ◽  
Delayed Rectifier ◽  
High Threshold ◽  
Electrophysiological Properties

As a step in exploring the functions of the inferior olive, we constructed a biophysical model of the olivary neurons to examine their unique electrophysiological properties. The model consists of two compartments to represent the known distribution of ionic currents across the cell membrane, as well as the dendritic location of the gap junctions and synaptic inputs. The somatic compartment includes a low-threshold calcium current ( I Ca_l), an anomalous inward rectifier current ( I h), a sodium current ( I Na), and a delayed rectifier potassium current ( I K_dr). The dendritic compartment contains a high-threshold calcium current ( I Ca_h), a calcium-dependent potassium current ( I K_Ca), and a current flowing into other cells through electrical coupling ( I c). First, kinetic parameters for these currents were set according to previously reported experimental data. Next, the remaining free parameters were determined to account for both static and spiking properties of single olivary neurons in vitro. We then performed a series of simulated pharmacological experiments using bifurcation analysis and extensive two-parameter searches. Consistent with previous studies, we quantitatively demonstrated the major role of I Ca_l in spiking excitability. In addition, I h had an important modulatory role in the spike generation and period of oscillations, as previously suggested by Bal and McCormick. Finally, we investigated the role of electrical coupling in two coupled spiking cells. Depending on the coupling strength, the hyperpolarization level, and the I Ca_l and I hmodulation, the coupled cells had four different synchronization modes: the cells could be in-phase, phase-shifted, or anti-phase or could exhibit a complex desynchronized spiking mode. Hence these simulation results support the counterintuitive hypothesis that electrical coupling can desynchronize coupled inferior olive cells.

scholarly journals Slow Delayed Rectifier Potassium Current Blockade Contributes Importantly to Drug-Induced Long QT Syndrome

2013 ◽  
Vol 6 (5) ◽  
pp. 1002-1009 ◽  
Author(s):  
Christiaan C. Veerman ◽  
Arie O. Verkerk ◽  
Marieke T. Blom ◽  
Christine A. Klemens ◽  
Pim N.J. Langendijk ◽  
...  
Keyword(s):  
Long Qt Syndrome ◽  
Potassium Current ◽  
Delayed Rectifier ◽  
Long Qt ◽  
Drug Induced ◽  
Delayed Rectifier Potassium Current ◽  
Qt Syndrome

scholarly journals Ginsenoside Rb1 exerts antiarrhythmic effects by inhibiting INa and ICaL in rabbit ventricular myocytes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Zhipei Liu ◽  
Lv Song ◽  
Peipei Zhang ◽  
Zhenzhen Cao ◽  
Jie Hao ◽  
...  
Keyword(s):  
Ion Channels ◽  
Action Potential ◽  
Potassium Current ◽  
Ischemia Reperfusion ◽  
Calcium Currents ◽  
Delayed Rectifier ◽  
Dependent Manner ◽  
Ginsenoside Rb1 ◽  
Patch Clamp Technique ◽  
High Calcium

AbstractGinsenoside Rb1 exerts its pharmacological action by regulating sodium, potassium and calcium ion channels in the membranes of nerve cells. These ion channels are also present in cardiomyocytes, but no studies have been reported to date regarding the effects of Rb1 on cardiac sodium currents (INa), L-type calcium currents (ICaL) and action potentials (APs). Additionally, the antiarrhythmic potential of Rb1 has not been assessed. In this study, we used a whole-cell patch clamp technique to assess the effect of Rb1 on these ion channels. The results showed that Rb1 inhibited INa and ICaL, reduced the action potential amplitude (APA) and maximum upstroke velocity (Vmax), and shortened the action potential duration (APD) in a concentration-dependent manner but had no effect on the inward rectifier potassium current (IK1), delayed rectifier potassium current (IK) or resting membrane potential (RMP). We also designed a pathological model at the cellular and organ level to verify the role of Rb1. The results showed that Rb1 abolished high calcium-induced delayed afterdepolarizations (DADs), depressed the increase in intracellular calcium ([Ca2+]i), relieved calcium overload and protected cardiomyocytes. Rb1 can also reduce the occurrence of ventricular premature beats (VPBs) and ventricular tachycardia (VT) in ischemia-reperfusion (I-R) injury.

scholarly journals P938Regulation of the delayed rectifier potassium current during the adrenergic adaptation of cardiomyocytes

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
D Kiss ◽  
T Hezso ◽  
B Kurtan ◽  
R Veress ◽  
D Baranyai ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Potassium Current ◽  
Slow Component ◽  
Delayed Rectifier ◽  
Total Charge ◽  
Current Profile ◽  
Calcium Calmodulin Dependent ◽  
Delayed Rectifier Potassium Current ◽  
Innovation And Technology ◽  
Dependent Protein

Abstract Funding Acknowledgements Supported by the ÚNKP-19-3 New National Excellence program of the Ministry for Innovation and Technology Introduction and aims Adaptation of the human heart to physical activity is a complex mechanism that includes the change of heart rate, morphology of the action potential (AP) among others. Stimulation of β-adrenergic receptors (β-AR) causes the shortening of the AP duration of ventricular cardiomyocytes. This is caused by the regulation of the potassium currents by the β-adrenergic signaling pathway. Our aim was to investigate the role of protein kinase A (PKA) and calcium/calmodulin-dependent protein kinase II (CaMKII) in the regulation of the slow component (IKs) of the delayed rectifier potassium current under β-AR activation. Methods Our experiments were performed on isolated canine cardiomyocytes from the left ventricle. The IKs current profile was determined under a ventricular AP. We used "AP voltage clamp" conditions in six experimental groups: Control (CTRL), β-AR stimulation with isoproterenol (ISO), CaMKII inhibition with KN-93 (KN-93), PKA inhibition with H-89 (H-89) β-AR stimulation with inhibited CaMKII (KN-93 + ISO), β-AR stimulation with inhibited PKA (H-89 + ISO). β-AR stimulation with inhibited CaMKII and PKA (KN-93 + H-89 + ISO) Results The highest current density of IKs was approximately 6 times higher and the charge delivered by IKs was about 8 times larger in the ISO group than in CTRL or KN-93 conditions. In the KN-93 + ISO group, IKs amplitude was about 60% smaller and delivered about half the total charge compared to the ISO group. In the H‑89 + ISO group, IKs was about 30% smaller and delivered 40% less total charge than in the ISO group. In the KN-93 + H-89 + ISO group the IKs did not changed sicnificantly. Conclusion Based on our results, CaMKII plays an important role in regulating IKs by β-AR stimulation.

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