Related Experiment Video

Updated: Jul 10, 2026

Cytosolic Calcium Measurements in Renal Epithelial Cells by Flow Cytometry
10:24

Cytosolic Calcium Measurements in Renal Epithelial Cells by Flow Cytometry

Published on: October 28, 2014

Cation channels in human embryonic kidney cells mediating calcium entry in response to extracellular low glucose

Su Wang1, Yuchun Gu

  • 1Department of Physiology, The Medical School, University of Birmingham, Edgbaston B15 2TT, UK.

Biochemical and Biophysical Research Communications
|November 21, 2007
PubMed

Insights

Low glucose triggers calcium (Ca2+) elevation in non-excitable HEK 293 cells, independent of known channels. This suggests a novel glucose sensing pathway in cells lacking voltage-gated calcium channels (VGCC).

Area of Science:

  • Cellular Biology
  • Physiology
  • Biochemistry

Background:

  • Glucose sensing is well-studied in excitable cells like pancreatic cells and neurons.
  • These cells utilize K(ATP), Kv, and TASK channels, and voltage-gated calcium channels (VGCC) for glucose-induced signaling.
  • The glucose sensing mechanism in non-excitable cells, which lack VGCC, remains largely unknown.

Purpose of the Study:

  • To investigate the mechanism of glucose sensing in non-excitable human embryonic kidney epithelial cells (HEK 293).
  • To determine the role of calcium ion (Ca2+) influx in response to low glucose in these cells.

Main Methods:

  • Utilized calcium ratio measurement to monitor intracellular Ca2+ levels ([Ca2+]i).
  • Employed patch clamping techniques to study ion currents.
  • Tested the effects of various modulators and inhibitors on glucose-induced Ca2+ entry.

Main Results:

  • Low glucose induced a significant, reversible increase in [Ca2+]i in HEK 293 cells.
  • This Ca2+ elevation was mediated by Ca2+ entry across the plasma membrane, independent of Kv channel closure.
  • The Ca2+ entry was voltage-independent, permeable to Na+ and Ca2+, and unaffected by common signaling pathway modulators or channel blockers.

Conclusions:

  • HEK 293 cells possess a novel glucose-sensing mechanism involving voltage-independent Ca2+ entry.
  • This pathway does not rely on previously identified glucose-sensing components like VGCC or modulation by PLC, AMPK, or tyrosine kinase.
  • Further research is needed to elucidate the specific molecular players in this newly identified glucose-sensitive pathway.

More Related Videos

Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli12:19

Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli

Published on: June 27, 2015

Imaging Calcium Dynamics in Subpopulations of Mouse Pancreatic Islet Cells08:03

Imaging Calcium Dynamics in Subpopulations of Mouse Pancreatic Islet Cells

Published on: November 26, 2019

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...
Glucose Absorption Into the Small Intestine01:26

Glucose Absorption Into the Small Intestine

Complex carbohydrates consumed cannot be absorbed into the small intestine in their original form. First, they must be hydrolyzed to a monosaccharide form such as glucose or galactose. These monosaccharides are then transported across the intestinal membrane and into the blood via transcellular transport. The intestinal epithelial cells allow the movement of these monosaccharides with a defined 'entry' through membrane transporter proteins present on their apical membrane and 'exit' via the...
The Role of Ion Channels in Neuronal Computation01:19

The Role of Ion Channels in Neuronal Computation

A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Voltage-gated Ion Channels01:26

Voltage-gated Ion Channels

Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
cAMP-dependent Protein Kinase Pathways01:25

cAMP-dependent Protein Kinase Pathways

Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
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,...