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Updated: Feb 24, 2026

Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique
Published on: November 11, 2022
CaV1.3 L-type Ca2+ channel contributes to the heartbeat by generating a dihydropyridine-sensitive persistent Na+
Futoshi Toyoda1, Pietro Mesirca2,3,4, Stefan Dubel2,3,4
1Department of Physiology, Shiga University of Medical Science, Otsu Seta-Tsukinowa, Shiga, 520-2192, Japan. toyoda@belle.shiga-med.ac.jp.
Abstract:
The spontaneous activity of sinoatrial node (SAN) pacemaker cells is generated by a functional interplay between the activity of ionic currents of the plasma membrane and intracellular Ca2+ dynamics. The molecular correlate of a dihydropyridine (DHP)-sensitive sustained inward Na+ current (I st), a key player in SAN automaticity, is still unknown. Here we show that I st and the L-type Ca2+ current (I Ca,L) share CaV1.3 as a common molecular determinant. Patch-clamp recordings of mouse SAN cells showed that I st is activated in the diastolic depolarization range, and displays Na+ permeability and minimal inactivation and sensitivity to I Ca,L activators and blockers. Both CaV1.3-mediated I Ca,L and I st were abolished in CaV1.3-deficient (CaV1.3-/-) SAN cells but the CaV1.2-mediated I Ca,L current component was preserved. In SAN cells isolated from mice expressing DHP-insensitive CaV1.2 channels (CaV1.2DHP-/-), I st and CaV1.3-mediated I Ca,L displayed overlapping sensitivity and concentration-response relationships to the DHP blocker nifedipine. Consistent with the hypothesis that CaV1.3 rather than CaV1.2 underlies I st, a considerable fraction of I Ca,L was resistant to nifedipine inhibition in CaV1.2DHP-/- SAN cells. These findings identify CaV1.3 channels as essential molecular components of the voltage-dependent, DHP-sensitive I st Na+ current in the SAN.
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