Related Experiment Video

Updated: Jul 26, 2026

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes
10:19

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

Published on: January 10, 2011

Electrophysiological effects of left ventricular hypertrophy. Effect of calcium and potassium channel blockade

P R Kowey1, T D Friechling, J Sewter

  • 1Cardiovascular Research Laboratory, Medical College of Pennsylvania, Philadelphia.

Circulation
|June 1, 1991
PubMed

Insights

Left ventricular hypertrophy (LVH) increases vulnerability to ventricular fibrillation by altering electrical recovery. Blocking potassium channels, but not calcium channels, protects against this arrhythmia.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Pharmacology

Background:

  • Left ventricular hypertrophy (LVH) can lead to cardiac arrhythmias.
  • The arrhythmogenic effects of LVH require detailed electrophysiological investigation.

Purpose of the Study:

  • To define the arrhythmogenic effects of LVH in an intact heart model.
  • To assess the impact of calcium and potassium channel blockade on LVH-induced arrhythmias.

Main Methods:

  • Electrophysiological assessment in a feline aortic-banding model of LVH.
  • Measurement of conduction times, excitability, refractoriness, and action potential duration.
  • Evaluation of ventricular fibrillation (VF) vulnerability and thresholds.

Main Results:

  • LVH cats exhibited increased vulnerability to VF, spontaneous VF, and lower VF thresholds compared to controls.
  • LVH caused greater dispersion of effective refractory period and action potential duration.
  • Risotilide (potassium channel blocker) reduced dispersion and ventricular vulnerability; verapamil (calcium channel blocker) had no significant effect.

Conclusions:

  • LVH significantly increases ventricular vulnerability to fibrillation by promoting dispersion of refractoriness and repolarization.
  • Voltage-dependent potassium channel blockade mitigates LVH-induced arrhythmogenesis.
  • Slow inward calcium channel blockade does not protect against LVH-related ventricular fibrillation.
Abstract

More Related Videos

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents10:53

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

Published on: July 3, 2013

Optical Mapping of Intra-Sarcoplasmic Reticulum Ca2+ and Transmembrane Potential in the Langendorff-perfused Rabbit Heart09:26

Optical Mapping of Intra-Sarcoplasmic Reticulum Ca2+ and Transmembrane Potential in the Langendorff-perfused Rabbit Heart

Published on: September 10, 2015

Related Concept Videos

Feedback Regulation of Calcium Concentration01:27

Feedback Regulation of Calcium Concentration

Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
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...
Ionic Strength: Effects on Chemical Equilibria01:19

Ionic Strength: Effects on Chemical Equilibria

The addition of an inert ionic compound increases the solubility of a sparingly soluble salt. For example, adding potassium nitrate to a saturated solution of calcium sulfate significantly enhances the solubility of calcium sulfate. Le Châtelier's principle cannot predict this shift in the equilibrium. Instead, this could be explained in terms of changes in the effective concentration of the ions in solution in the presence of added inert salt.
In this solution, the primary cation—the calcium...
Relaxation of Skeletal Muscles01:29

Relaxation of Skeletal Muscles

The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
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,...
Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.