Cloning and expression of cDNA and genomic clones encoding three delayed rectifier potassium channels in rat brain

Swanson, Richard; Marshall, John; Smith, Jeffrey S.; Williams, Jacinta B.; Boyle, Mary B.; Folander, Kimberly; Luneau, Christopher J.; Antanavage, Joanne; Oliva, Carlos; Buhrow, S A; Bennet, C. Frank; Stein, Robert B.; Kaczmarek, Leonard K.

doi:10.1016/0896-6273(90)90146-7

Cited by 307 publications

(187 citation statements)

References 40 publications

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“…These results are consistent with a previous study showing that I sus is significantly reduced in the left ventricular endocardium after shortterm infarction (61). The molecular correlates of I sus remains uncertain, but three candidate K ϩ channel genes (Kv1.2, Kv1.5, and Kv2.1) are expressed in the rat heart (16,51,53). In the right ventricle, RNase protection assays (data not shown) revealed that the percentage reductions in mRNA levels after MI did not reach significance for Kv1.2, (23.7 Ϯ 15.3%, n ϭ 5, P ϭ 0.19), Kv1.5 (22.4 Ϯ 11.4%, n ϭ 5, P ϭ 0.11) or Kv2.1 (27.0 Ϯ 9.8%, n ϭ 5, P ϭ 0.06) genes.…”

Section: Resultssupporting

confidence: 82%

Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,I_toK⁺currents, and [Ca²⁺]_itransients

Kaprielian

Sah

Nguyen

et al. 2002

American Journal of Physiology-Heart and Circulatory Physiology

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(Ito) has been shown to vary between different regions of the normal myocardium and to be reduced in heart disease. In this study, we measured regional changes in action potential duration (APD), I to, and intracellular Ca 2ϩ concentration ([Ca 2ϩ ]i) transients of ventricular myocytes derived from the right ventricular free wall (RVW) and interventricular septum (SEP) 8 wk after myocardial infarction (MI). At ϩ40 mV, I to density in sham-operated hearts was significantly higher (P Ͻ 0.01) in the RVW (15.0 Ϯ 0.8 pA/pF, n ϭ 47) compared with the SEP (7.0 Ϯ 1.1 pA/pF, n ϭ 18). After MI, I to density was not reduced in SEP myocytes but was reduced (P Ͻ 0.01) in RVW myocytes (8.7 Ϯ 1.0 pA/pF, n ϭ 26) to levels indistinguishable from post-MI SEP myocytes. These changes in I to density correlated with Kv4.2 (but not Kv4.3) protein expression. By contrast, Kv1.4 expression was significantly higher in the RVW compared with the SEP and increased significantly after MI in RVW. APD measured at 50% or 90% repolarization was prolonged, whereas peak [Ca 2ϩ ]i transients amplitude was higher in the SEP compared with the RVW in sham myocytes. These regional differences in APD and [Ca 2ϩ ]i transients were eliminated by MI. Our results demonstrate that the significant regional differences in I to density, APD, and [Ca 2ϩ ]i between RVW and SEP are linked to a variation in Kv4.2 expression, which largely disappears after MI. right ventricle; septum; heart disease; contraction THERE ARE MARKED DIFFERENCES in the action potential duration (APD) in different regions of the mammalian ventricle (4,15,18,39,58). This electrical heterogeneity in normal myocardium correlates with regional differences in the Ca 2ϩ -independent transient outward K ϩ current density (I to ) (5,15,18,34,35,43) as well as in gene expression of K ϩ channels (8,16,58). APD prolongation and reductions in I to density occur in rat heart after left anterior descending coronary artery ligation (2, 43, 58), aortic banding (5, 22, 55), as well as after treatment with either catecholamine (11) or monocrotaline (32, 33). Depending on the model, the extent of I to density changes in disease may not be uniform throughout the ventricle (2, 5, 11, 22, 55), thereby leading to possible losses of electrical heterogeneity and increased susceptibility to arrhythmias (3).Aside from electrical heterogeneity, regional differences in other myocardial properties also exist. For example, systolic intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) is higher in the endocardium than in the epicardium (19,54), consistent with the notion that the endocardium may play a more important role in contraction compared with the epicardium. The underlying basis for the regional differences in contraction is currently unknown but may be related to a heterogeneous transmural expression of Ca 2ϩ handling proteins (26, 31). Alternatively, APD might also play a key role because the action potential profile is an important determinant of the inotropic state of the heart in both normal (7,42,54) and hy...

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Section: Resultssupporting

confidence: 82%

Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,I_toK⁺currents, and [Ca²⁺]_itransients

Kaprielian

Sah

Nguyen

et al. 2002

American Journal of Physiology-Heart and Circulatory Physiology

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“…These data indicate a regulatory mechanism acting later in development than for the other K+ channel polypeptides studied. The expression of Kvl.5 in the hippocampus parallels observed developmental increases in Kvl.5 mRNA in whole brain (Swanson et al, 1990). The size of Kv 1.5 in brain (M,-= 63 kDa) is similar to the predicted molecular weight deduced from the Kv1.5 cDNA (66.5 kDa; Swanson et al, 1990).…”

Section: Resultsmentioning

confidence: 65%

Differential spatiotemporal expression of K+ channel polypeptides in rat hippocampal neurons developing in situ and in vitro

1995

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Hippocampal neurons are highly plastic in their excitable properties, both during development and in the adult brain. As voltage-sensitive K+ channels are major determinants of membrane excitability, one mechanism for generating plasticity is through regulation of K+ channel activity. To gain insights into the regulation of K+ channels in the hippocampus, we have analyzed the spatiotemporal expression patterns of five K+ channel polypeptides in rat hippocampal neurons developing in situ and in vitro. Delayed rectifier-type channels (Kv1.5, Kv2.1, and Kv2.2) are expressed on all neuronal somata and proximal dendrites, while A-type channels (Kv1.4 and Kv4.2) are present distally on distinct subpopulations of neurons. The development of these patterns in situ is monotonic; that is, while the time and spatial development varies among the channels, each K+ channel subtype initially appears in its adult pattern, suggesting that the mechanisms underlying spatial patterning operate through development. Immunoblots confirm the differential temporal expression of K+ channels in the developing hippocampus, and demonstrate developmentally regulated changes in the microheterogeneity of some K+ channel polypeptide species. Temporal expression patterns of all five K+ channels observed in situ are retained in vitro, while certain aspects of cellular and subcellular localization are altered for some of the K+ channel polypeptides studied. Similarities in K+ channel polypeptide expression in situ and in vitro indicate that the same regulatory mechanisms are controlling spatiotemporal patterning in both situations. However, differences between levels of expression for all subtypes studied except Kv2.1 indicate additional mechanisms operating in situ but absent in vitro that are important in determining polypeptide abundance.

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“…16) Kv1.5 cDNA 17) was cloned into the plasmid expression vector pCR3.1 (Invitrogen Corp., San Diego, CA, U.S.A.). CHO cells were transfected with Kv1.5 cDNA using FuGENE6 reagent (Boehringer Mannheim, Indianapolis, IN, U.S.A.).…”

Section: Stable Transfection and Cell Culturementioning

confidence: 99%

Inhibitory Action of Fluvoxamine on Kv1.5 Currents

Lee

Hahn

Choi

2010

Biological & Pharmaceutical Bulletin

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Fluvoxamine is a selective serotonin reuptake inhibitor that exerts antidepressant activity by inhibiting the reuptake of serotonin, or 5-hydroxytryptamine, in the central nervous system. Fluvoxamine shows negligible affinity for other neurotransmitter reuptake systems, [1][2][3][4] so it may have advantages over other antidepressants in the treatment of depression. For example, tricyclic antidepressant (TCA) is associated with an increased risk of cardiovascular events. [5][6][7][8][9] However, accumulating evidence suggests that fluvoxamine may increase cardiovascular risk through inhibition of the human ether-a-go-go related (HERG) potassium channel. 10)The drug may also be associated with ventricular arrhythmia.11) Pharmacological blockade of cardiac muscle voltage-gated K ϩ channels (Kv channels) is associated with adverse cardiac arrhythmias, suggesting that fluvoxamine may interact with cardiac Kv channels. However, the exact effects of fluvoxamine on cardiac Kv channels remain to be elucidated.Kv1.5 is a cardiovascular-specific Kv channel isoform. It has an important role in determining the length of cardiac action potentials, and is a target of antiarrhythmic drugs. 12)Kv1.5 is rapidly activated and is difficult to inactivate, so it contributes to the repolarization of atrial action potentials. Kv1.5 dysfunction results in prolonged cardiac action potentials, eventually leading to cardiac arrhythmias with serious morbidity. [13][14][15] In this study, we investigated whether fluvoxamine interacts with Kv1.5 cloned from rat brain and determined the mechanisms by which fluvoxamine acts on Kv1.5. MATERIALS AND METHODS Stable Transfection and Cell CultureChinese hamster ovary (CHO) cells expressing Kv1.5 channels from rat brain were used for electrophysiological recordings.16) Kv1.5 cDNA 17) was cloned into the plasmid expression vector pCR3.1 (Invitrogen Corp., San Diego, CA, U.S.A.). CHO cells were transfected with Kv1.5 cDNA using FuGENE6 reagent (Boehringer Mannheim, Indianapolis, IN, U.S.A.).Transfected cells were cultured in Iscove's modified Dulbecco's medium (Invitrogen Corp.) supplemented with 10% fetal bovine serum, 2 mM glutamine, 0.1 mM hypoxanthine, 0.01 mM thymidine, and 300 mg/ml G418 (A.G. Scientific, San Diego, CA, U.S.A.) in 95% humidified air-5% CO 2 at 37°C. Cultures were passaged every 4-5 d by brief trypsinethylenediaminetetraacetic acid treatment, seeded onto glass coverslips (diameter: 12 mm, Fisher Scientific, Pittsburgh, PA, U.S.A.) in a Petri dish, and used for electrophysiological recordings after 12-24 h.Electrophysiological Recordings Kv1.5 currents were recorded from CHO cells using a whole-cell patch-clamp technique 18) at room temperature (22-23°C). Micropipettes fabricated from glass capillary tubing (PG10165-4; World Precision Instruments, Sarasota, FL, U.S.A.) with a doublestage vertical puller (PC-10; Narishige, Tokyo) had a tip resistance of 2-3 MW when filled with pipette solution. Wholecell currents were amplified with a MultiClamp 700B amplifier (Molecular Devices, S...

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Cloning and expression of cDNA and genomic clones encoding three delayed rectifier potassium channels in rat brain

Cited by 307 publications

References 40 publications

Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,I_toK⁺currents, and [Ca²⁺]_itransients

Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,I_toK⁺currents, and [Ca²⁺]_itransients

Differential spatiotemporal expression of K+ channel polypeptides in rat hippocampal neurons developing in situ and in vitro

Inhibitory Action of Fluvoxamine on Kv1.5 Currents

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Cloning and expression of cDNA and genomic clones encoding three delayed rectifier potassium channels in rat brain

Cited by 307 publications

References 40 publications

Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,ItoK+currents, and [Ca2+]itransients

Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,ItoK+currents, and [Ca2+]itransients

Differential spatiotemporal expression of K+ channel polypeptides in rat hippocampal neurons developing in situ and in vitro

Inhibitory Action of Fluvoxamine on Kv1.5 Currents

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Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,I_toK⁺currents, and [Ca²⁺]_itransients

Myocardial infarction in rat eliminates regional heterogeneity of AP profiles,I_toK⁺currents, and [Ca²⁺]_itransients