Related Experiment Video

Updated: Oct 13, 2026

Light-Induced In Situ Transmission Electron Microscopy for Observation of the Liquid-Soft Matter Interaction
05:33

Light-Induced In Situ Transmission Electron Microscopy for Observation of the Liquid-Soft Matter Interaction

Published on: July 26, 2022

The photodynamic action of methylene blue on the ion channels of Paramecium causes cell damage

F Saitow1, Y Nakaoka

  • 1Department of Biophysical Engineering, Osaka University, Japan.

Photochemistry and Photobiology
|May 1, 1997
PubMed

Insights

Mutant Paramecium strains survived longer under methylene blue (MB) photodynamic stress due to a defect in calcium-dependent potassium channels. This defect altered membrane potential, reducing calcium influx and increasing survival time.

Area of Science:

  • Cell biology
  • Photobiology
  • Ion channel physiology

Background:

  • Methylene blue (MB) induces photodynamic effects in cells.
  • Paramecium serves as a model organism for studying cellular responses to stress.

Purpose of the Study:

  • To investigate the photodynamic effects of MB on wild-type and mutant Paramecium strains.
  • To elucidate the cellular mechanisms underlying differential survival rates.

Main Methods:

  • Comparative analysis of survival and cell motility under MB and light exposure.
  • Measurement of resting and light-induced membrane potentials.
  • Voltage clamp experiments to assess ion channel activity.

Main Results:

  • Mutant strains exhibited approximately threefold longer survival times compared to wild-type.
  • Photodynamic action induced depolarization in mutants and hyperpolarization in wild-type cells.
  • Mutant cells showed reduced outward currents and tail currents under voltage clamp.

Conclusions:

  • The mutant strain possesses a defect in the activation of Ca(2+)-dependent K+ channels.
  • This defect likely reduces Ca2+ influx by suppressing membrane hyperpolarization.
  • The reduced Ca2+ influx contributes to the extended survival of mutant cells under photodynamic stress.

More Related Videos

A Photodynamic Approach to Study Function of Intracellular Vesicle Rupture05:16

A Photodynamic Approach to Study Function of Intracellular Vesicle Rupture

Published on: March 17, 2023

A Thermoplasmonic Approach for Investigating Plasma Membrane Repair in Living Cells and Model Membranes06:32

A Thermoplasmonic Approach for Investigating Plasma Membrane Repair in Living Cells and Model Membranes

Published on: January 19, 2024

Related Concept Videos

Channel Rhodopsins01:11

Channel Rhodopsins

Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
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,...
Photoreceptors and Visual Pathways01:22

Photoreceptors and Visual Pathways

At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
Cellular Injury IV: Necrosis01:16

Cellular Injury IV: Necrosis

Necrosis is a form of irreversible cell death caused by severe injury such as ischemia, toxins, or trauma. Unlike programmed cell death, it is an uncontrolled, pathological process that typically provokes inflammation in surrounding tissues.Pathophysiologic ChangesNecrosis begins when cells sustain critical damage, leading to swelling of organelles, particularly mitochondria, and rapid ATP depletion. As energy levels decline, membrane ion pumps fail, leading to calcium influx and eventually,...