Related Experiment Video

Updated: Jul 11, 2026

Live Cell Calcium Imaging Combined with siRNA Mediated Gene Silencing Identifies Ca2+ Leak Channels in the ER Membrane and their Regulatory Mechanisms
13:40

Live Cell Calcium Imaging Combined with siRNA Mediated Gene Silencing Identifies Ca2+ Leak Channels in the ER Membrane and their Regulatory Mechanisms

Published on: July 7, 2011

Somatostatin stimulates Ca(2+)-activated K+ channels through protein dephosphorylation

R E White1, A Schonbrunn, D L Armstrong

  • 1Laboratory of Cellular and Molecular Pharmacology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.

Nature
|June 13, 1991
PubMed

Insights

Somatostatin, a neuropeptide, activates large-conductance potassium channels (BK) in pituitary tumor cells. This activation occurs via protein dephosphorylation, not direct ion or G protein effects.

Area of Science:

  • Neuroendocrinology
  • Cellular Physiology
  • Molecular Biology

Background:

  • Somatostatin is a neuropeptide that regulates secretion in various tissues.
  • In pituitary tumor cells, somatostatin inhibits secretion via two pertussis toxin-sensitive pathways.
  • One pathway inhibits adenylyl cyclase; the other is a cAMP-independent mechanism affecting Ca2+ influx.

Purpose of the Study:

  • To elucidate the predominant electrophysiological mechanism of somatostatin action in pituitary tumor cells.
  • To identify the specific ion channels and signaling pathways involved in somatostatin's inhibitory effects.

Main Methods:

  • Electrophysiological recordings from metabolically intact mammalian pituitary tumor cells.
  • Investigation of the effects of somatostatin on ion channel activity.
  • Analysis of the roles of Ca2+, cAMP, and G proteins in somatostatin signaling.

Main Results:

  • Somatostatin significantly increases the activity of large-conductance Ca(2+)- and voltage-activated K+ channels (BK).
  • This somatostatin-induced BK channel activation is independent of direct effects from Ca2+, cAMP, or G proteins.
  • The primary mechanism involves somatostatin stimulating BK channel activity through protein dephosphorylation.

Conclusions:

  • The major electrophysiological effect of somatostatin in pituitary tumor cells is the stimulation of BK channels.
  • Protein dephosphorylation is identified as the key signaling event mediating somatostatin's action on BK channels.
  • This finding clarifies a previously unidentified cAMP-independent mechanism of somatostatin.

More Related Videos

Functional Site-Directed Fluorometry in Native Cells to Study Skeletal Muscle Excitability12:26

Functional Site-Directed Fluorometry in Native Cells to Study Skeletal Muscle Excitability

Published on: June 2, 2023

Single-Cell Calcium Imaging for Studying the Activation of Calcium Ion Channels07:17

Single-Cell Calcium Imaging for Studying the Activation of Calcium Ion Channels

Published on: December 13, 2024

Related Concept Videos

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...
Mechanically-gated Ion Channels01:12

Mechanically-gated Ion Channels

Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous...
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,...
IP3/DAG Signaling Pathway01:11

IP3/DAG Signaling Pathway

Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the  phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
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...
Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...