Depressed transient outward potassium current density in catecholamine-depleted rat ventricular myocytes - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles AJP - Heart and Circulatory Physiology Year : 2002

Depressed transient outward potassium current density in catecholamine-depleted rat ventricular myocytes

Abstract

The effect of catecholamine depletion (induced by prior treatment with reserpine) was studied in Wistar rat ventricular myocytes using whole cell voltage-clamp methods. Two calcium-independent outward currents, the transient outward potassium current (I(to)) and the sustained outward potassium current (I(sus)), were measured. Reserpine treatment decreased tissue norepinephrine content by 97%. Action potential duration in the isolated perfused heart was significantly increased in reserpine-treated hearts. In isolated ventricular myocytes, I(to) density was decreased by 49% in reserpine-treated rats. This treatment had no effect on I(sus). The I(to) steady-state inactivation-voltage relationship and recovery from inactivation remained unchanged, whereas the conductance-voltage activation curve for reserpine-treated rats was significantly shifted (6.7 mV) toward negative potentials. The incubation of myocytes with 10 microM norepinephrine for 7-10 h restored I(to), an effect that was abolished by the presence of actinomycin D. Norepinephrine (0.5 microM) had no effect on I(to). However, in the presence of both 0.5 microM norepinephrine and neuropeptide Y (0.1 microM), I(to) density was restored to its control value. These results suggest that the sympathetic nervous system is involved in I(to) regulation. Sympathetic norepinephrine depletion decreased the number of functional channels via an effect on the alpha-adrenergic cascade and norepinephrine is able to restore expression of I(to) channels.
Fichier principal
Vignette du fichier
2002_Bru-Mercier_American Journal of Physiology_1.pdf (289.79 Ko) Télécharger le fichier
Origin Publisher files allowed on an open archive
Loading...

Dates and versions

hal-02683189 , version 1 (01-06-2020)

Identifiers

Cite

Gilles Bru-Mercier, Edith Deroubaix, Delphine Rousseau, Alain Coulombe, Jean-François Renaud. Depressed transient outward potassium current density in catecholamine-depleted rat ventricular myocytes. AJP - Heart and Circulatory Physiology, 2002, 282 (4), pp.H1237-H1247. ⟨10.1152/ajpheart.00180.2001⟩. ⟨hal-02683189⟩
22 View
82 Download

Altmetric

Share

Gmail Mastodon Facebook X LinkedIn More