Related Experiment Video

Updated: Sep 28, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
10:53

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Published on: July 3, 2013

Selectivity of different calcium antagonists on T- and L-type calcium currents in guinea-pig ventricular myocytes

Petra De Paoli1, Elisabetta Cerbai, Bernd Koidl

  • 1Department of Preclinical and Clinical Pharmacology, Centre of Molecular Medicine, University of Firenze, Viale G. Pieraccini 6, 50139 Firenze, Italy.

Pharmacological Research
|November 30, 2002
PubMed

Insights

Calcium channel blockers exhibit varying selectivity for cardiac T-type and L-type calcium channels. Mibefradil selectively blocks T-type channels, while others show different T/L selectivity profiles.

Area of Science:

  • Cardiovascular Pharmacology
  • Ion Channel Physiology

Background:

  • Cardiac myocytes possess both L-type and T-type calcium channels.
  • L-type channels are targeted by traditional blockers, while T-type channels are less sensitive.
  • Mibefradil is known for selective T-type calcium channel blockade.

Purpose of the Study:

  • To compare the T/L calcium channel blocking selectivity of various calcium channel blockers.
  • To evaluate the effects of amlodipine, lacidipine, verapamil, diltiazem, and mibefradil on both channel types in single cardiac cells.

Main Methods:

  • Patch-clamp recordings were performed on single guinea-pig ventricular myocytes.
  • Superfusion with a Na(+)- and K(+)-free solution minimized overlapping currents.
  • Equieffective concentrations for L-type current blockade were used for each tested compound.

Main Results:

  • All tested blockers inhibited T-type calcium current at concentrations blocking <30% of L-type current.
  • Inhibition of T-type current ranged from 0.8% (diltiazem) to 28% (mibefradil).
  • Mibefradil demonstrated the highest T-selectivity; lacidipine and diltiazem were L-selective; verapamil and amlodipine showed no selectivity.

Conclusions:

  • Calcium channel blockers can be differentiated based on their T/L selectivity.
  • The findings highlight distinct pharmacological profiles for different calcium channel blockers.
  • This differentiation is crucial for understanding their cardiac effects and therapeutic applications.

More Related Videos

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current06:22

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Published on: November 3, 2020

Contractions of Human-iPSC-derived Cardiomyocyte Syncytia Measured with a Ca-sensitive Fluorescent Dye in Temperature-controlled 384-well Plates07:42

Contractions of Human-iPSC-derived Cardiomyocyte Syncytia Measured with a Ca-sensitive Fluorescent Dye in Temperature-controlled 384-well Plates

Published on: October 18, 2018

Related Concept Videos

Antihypertensive Drugs: Action of Calcium Channel Blockers01:18

Antihypertensive Drugs: Action of Calcium Channel Blockers

Calcium ions are essential to contract smooth muscle cells in blood vessels. They enter these cells through voltage-dependent calcium channels, specifically L-type calcium channels in the cell membrane. These L-type calcium channels are integral to the excitation-contraction coupling process in smooth muscle. When a stimulus is received by smooth muscle cells, their membrane depolarizes. This alteration in membrane potential instigates the opening of L-type calcium channels. As a result,...
G-Protein Gated Ion Channels01:21

G-Protein Gated Ion Channels

GPCRs are primarily responsible for our sense of smell, taste, and vision.  The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory organs,...
Ligand-Gated Ion Channel Receptor: Gating Mechanism01:30

Ligand-Gated Ion Channel Receptor: Gating Mechanism

Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...
Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers01:20

Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers

Class IV antiarrhythmic drugs, such as verapamil and diltiazem, block calcium channels. They primarily affect the heart, slowing the conduction in calcium-dependent tissues like the SA and AV nodes. These drugs manage reentrant supraventricular tachycardia (SVT) and reduce ventricular rate in atrial flutter/fibrillation.
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers01:22

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
Ligand-gated Ion Channels01:19

Ligand-gated Ion Channels

Ligand-gated ion channels are transmembrane proteins with a channel for ions to pass through and a binding site for a ligand. The channel opens only when a ligand attaches to the binding site.
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...