scholarly journals Functional properties of K+currents in adult mouse ventricular myocytes

2004 ◽  
Vol 559 (3) ◽  
pp. 777-798 ◽  
Author(s):  
Judith Brouillette ◽  
Robert B. Clark ◽  
Wayne R. Giles ◽  
Céline Fiset
Keyword(s):  
Functional Properties ◽  
Adult Mouse ◽  
Ventricular Myocytes ◽  
Adult Mouse Ventricular Myocytes ◽  
K Currents

scholarly journals Four Kinetically Distinct Depolarization-activated K+ Currents in Adult Mouse Ventricular Myocytes

1999 ◽  
Vol 113 (5) ◽  
pp. 661-678 ◽  
Author(s):  
Haodong Xu ◽  
Weinong Guo ◽  
Jeanne M. Nerbonne
Keyword(s):  
Adult Mouse ◽  
Ventricular Myocytes ◽  
Left Ventricular ◽  
Inactivation Kinetics ◽  
Transient Outward Current ◽  
Steady State Current ◽  
K Current ◽  
Adult Mouse Ventricular Myocytes ◽  
K Currents ◽  
In Cells

In the experiments here, the time- and voltage-dependent properties of the Ca2+-independent, depolarization-activated K+ currents in adult mouse ventricular myocytes were characterized in detail. In the majority (65 of 72, ≈ 90%) of cells dispersed from the ventricles, analysis of the decay phases of the outward currents revealed three distinct K+ current components: a rapidly inactivating, transient outward K+ current, Ito,f (mean ± SEM τdecay = 85 ± 2 ms); a slowly (mean ± SEM τdecay = 1,162 ± 29 ms) inactivating K+ current, IK,slow; and a non inactivating, steady state current, Iss. In a small subset (7 of 72, ≈ 10%) of cells, Ito,f was absent and a slowly inactivating (mean ± SEM τdecay = 196 ± 7 ms) transient outward current, referred to as Ito,s, was identified; the densities and properties of IK,slow and Iss in Ito,s-expressing cells are indistinguishable from the corresponding currents in cells with Ito,f. Microdissection techniques were used to remove tissue pieces from the left ventricular apex and from the ventricular septum to allow the hypothesis that there are regional differences in Ito,f and Ito,s expression to be tested directly. Electrophysiological recordings revealed that all cells isolated from the apex express Ito,f (n = 35); Ito,s is not detected in these cells (n = 35). In the septum, by contrast, all of the cells express Ito,s (n = 28) and in the majority (22 of 28, 80%) of cells, Ito,f is also present. The density of Ito,f (mean ± SEM at +40 mV = 6.8 ± 0.5 pA/pF, n = 22) in septum cells, however, is significantly (P < 0.001) lower than Ito,f density in cells from the apex (mean ± SEM at +40 mV = 34.6 ± 2.6 pA/pF, n = 35). In addition to differences in inactivation kinetics, Ito,f, Ito,s, and IK,slow display distinct rates of recovery (from inactivation), as well as differential sensitivities to 4-aminopyridine (4-AP), tetraethylammonium (TEA), and Heteropoda toxin-3. IK,slow, for example, is blocked selectively by low (10–50 μM) concentrations of 4-AP and by (≥25 mM) TEA. Although both Ito,f and Ito,s are blocked by high (>100 μM) 4-AP concentrations and are relatively insensitive to TEA, Ito,f is selectively blocked by nanomolar concentrations of Heteropoda toxin-3, and Ito,s (as well as IK,slow and Iss) is unaffected. Iss is partially blocked by high concentrations of 4-AP or TEA. The functional implications of the distinct properties and expression patterns of Ito,f and Ito,s, as well as the likely molecular correlates of these (and the IK,slow and Iss) currents, are discussed.

Mechanisms of the negative inotropic effects of sphingosine-1-phosphate on adult mouse ventricular myocytes

2008 ◽  
Vol 294 (2) ◽  
pp. H736-H749 ◽  
Author(s):  
Lee K. Landeen ◽  
Dorothy A. Dederko ◽  
Colleen S. Kondo ◽  
Betty S. Hu ◽  
Nakon Aroonsakool ◽  
...  
Keyword(s):  
Adult Mouse ◽  
Calcium Release ◽  
Ventricular Myocytes ◽  
Receptor Subtype ◽  
Inotropic Effects ◽  
Subtype Specificity ◽  
Sphingosine 1 Phosphate ◽  
Intracellular Ca ◽  
Adult Mouse Ventricular Myocytes ◽  
Negative Inotropic Effects

Sphingosine-1-phosphate (S1P) induces a transient bradycardia in mammalian hearts through activation of an inwardly rectifying K+ current ( IKACh) in the atrium that shortens action potential duration (APD) in the atrium. We have investigated probable mechanisms and receptor-subtype specificity for S1P-induced negative inotropy in isolated adult mouse ventricular myocytes. Activation of S1P receptors by S1P (100 nM) reduced cell shortening by ∼25% (vs. untreated controls) in field-stimulated myocytes. S1P1 was shown to be involved by using the S1P1-selective agonist SEW2871 on myocytes isolated from S1P3-null mice. However, in these myocytes, S1P3 can modulate a somewhat similar negative inotropy, as judged by the effects of the S1P1 antagonist VPC23019 . Since S1P1 activates Gi exclusively, whereas S1P3 activates both Gi and Gq, these results strongly implicate the involvement of mainly Gi. Additional experiments using the IKACh blocker tertiapin demonstrated that IKACh can contribute to the negative inotropy following S1P activation of S1P1 (perhaps through Giβγ subunits). Mathematical modeling of the effects of S1P on APD in the mouse ventricle suggests that shortening of APD (e.g., as induced by IKACh) can reduce L-type calcium current and thus can decrease the intracellular Ca2+ concentration ([Ca2+]i) transient. Both effects can contribute to the observed negative inotropic effects of S1P. In summary, these findings suggest that the negative inotropy observed in S1P-treated adult mouse ventricular myocytes may consist of two distinctive components: 1) one pathway that acts via Gi to reduce L-type calcium channel current, blunt calcium-induced calcium release, and decrease [Ca2+]i; and 2) a second pathway that acts via Gi to activate IKACh and reduce APD. This decrease in APD is expected to decrease Ca2+ influx and reduce [Ca2+]i and myocyte contractility.

Negative inotropic effects of angiotensin II, endothelin-1 and phenylephrine in indo-1 loaded adult mouse ventricular myocytes

Life Sciences ◽  
2002 ◽  
Vol 70 (10) ◽  
pp. 1173-1184 ◽  
Author(s):  
Kiyoharu Sakurai ◽  
Ikuo Norota ◽  
Hisao Tanaka ◽  
Isao Kubota ◽  
Hitonobu Tomoike ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Adult Mouse ◽  
Ventricular Myocytes ◽  
Inotropic Effects ◽  
Endothelin 1 ◽  
Adult Mouse Ventricular Myocytes ◽  
Negative Inotropic Effects

scholarly journals BAG3 regulates contractility and Ca2+ homeostasis in adult mouse ventricular myocytes

2016 ◽  
Vol 92 ◽  
pp. 10-20 ◽  
Author(s):  
Arthur M. Feldman ◽  
Jennifer Gordon ◽  
JuFang Wang ◽  
Jianliang Song ◽  
Xue-Qian Zhang ◽  
...  
Keyword(s):  
Adult Mouse ◽  
Ventricular Myocytes ◽  
Adult Mouse Ventricular Myocytes

scholarly journals Characterization of a Slowly Inactivating Outward Current in Adult Mouse Ventricular Myocytes

1998 ◽  
Vol 83 (8) ◽  
pp. 806-814 ◽  
Author(s):  
Jun Zhou ◽  
Andreas Jeron ◽  
Barry London ◽  
Xingqiang Han ◽  
Gideon Koren
Keyword(s):  
Adult Mouse ◽  
Ventricular Myocytes ◽  
Outward Current ◽  
Adult Mouse Ventricular Myocytes
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