Regional contributions of Kv1.4, Kv4.2, and Kv4.3 to transient outward K1 current in rat ventricle
نویسنده
چکیده
Wickenden, A. D., T. J. Jegla, R. Kaprielian, and P. H. Backx. Regional contributions of Kv1.4, Kv4.2, and Kv4.3 to transient outward K1 current in rat ventricle. Am. J. Physiol. 276 (Heart Circ. Physiol. 45): H1599–H1607, 1999.—The aim of the present study was to assess differences in transient outward potassium current (Ito) between the right ventricular free wall and the interventricular septum of the adult rat ventricle and to evaluate the relative contributions of Kv4.2, Kv4.3, and Kv1.4 to Ito in these regions. The results show that Ito is composed of both rapidly and slowly recovering components in the right wall and septum. The fast component had a significantly higher density in the right free wall than in the septum, whereas the slow component did not differ between the two sites. Kv4.2 mRNA and protein levels were also highest in the right wall and correlated with Ito density, whereas Kv4.3 was expressed uniformly in these regions. The kinetics of the rapidly recovering component of Ito in myocytes was similar to that recorded in tsa-201 cells expressing Kv4.2 and Kv4.3 channels. Kv1.4 mRNA and protein expression correlated well with the density of the slowly recovering Ito, whereas the recovery kinetics of the slow component were identical to Kv1.4 expressed in tsa-201 cells. In conclusion, expression of Kv1.4, Kv4.2, and Kv4.3 differs between regions in rat hearts. Regionally specific differences in the genetic composition of Ito can account for the region-specific properties of this current.
منابع مشابه
Regional contributions of Kv1.4, Kv4.2, and Kv4.3 to transient outward K+ current in rat ventricle.
The aim of the present study was to assess differences in transient outward potassium current ( I to) between the right ventricular free wall and the interventricular septum of the adult rat ventricle and to evaluate the relative contributions of Kv4.2, Kv4.3, and Kv1.4 to I to in these regions. The results show that I to is composed of both rapidly and slowly recovering components in the right...
متن کاملAltered K(+) channel gene expression in diabetic rat ventricle: isoform switching between Kv4.2 and Kv1.4.
Expression of voltage-gated K(+) channels encoding the K(+) independent transient outward current in the streptozocin-induced diabetic (DM) rat ventricle was studied to determine the basis for slowed cardiac repolarization in diabetes mellitus. Although hypertrophy was not detected in diabetic rats at 12 wk after streptozocin treatment, ventricular Kv4.2 mRNA levels decreased 41% relative to no...
متن کاملRole of heteromultimers in the generation of myocardial transient outward K+ currents.
Previous studies have demonstrated a role for Kv4 alpha subunits in the generation of the fast transient outward K+ current, I(to,f), in the mammalian myocardium. The experiments here were undertaken to explore the role of homomeric/heteromeric assembly of Kv4.2 and Kv4.3 and of the Kv channel accessory subunit, KChIP2, in the generation of mouse ventricular I(to,f). Western blots reveal that t...
متن کاملMolecular aspects of adrenergic modulation of the transient outward current.
Transient outward channels have a different impact on action potential configuration in small mammals compared to large mammals. Small mammals depend primarily on Ito1 for repolarization, while in larger animals Ito1 only indirectly determines action potential duration by setting the level of the plateau. Transient outward channel expression and distribution also differ between animal species. ...
متن کاملMolecular correlates of altered expression of potassium currents in failing rabbit myocardium.
Action potential (AP) prolongation is a hallmark of failing myocardium. Functional downregulation of K currents is a prominent feature of cells isolated from failing ventricles. The detailed changes in K current expression differ depending on the species, the region of the heart, and the mechanism of induction of heart failure. We used complementary approaches to study K current downregulation ...
متن کامل