alexa All classes of calcium channel couple with equal efficiency to exocytosis in rat melanotropes, inducing linear stimulus-secretion coupling.
Immunology

Immunology

Journal of Cell Signaling

Author(s): Mansvelder HD, Kits KS

Abstract Share this page

Abstract 1. The contribution of low voltage-activated (LVA) T-type Ca2+ channels and four different types of high voltage-activated (HVA) Ca2+ channel to exocytosis, and the relationship between calcium influx and exocytosis during action potentials (APs) were studied in pituitary melanotropes. 2. Selective HVA Ca2+ channel blockers reduced exocytosis, monitored by membrane capacitance measurements, proportional to the reduction in Ca2+ influx. The efficacy of Ca2+ in stimulating exocytosis did not change in the presence of the Ca2+ channel blockers, indicating that all HVA Ca2+ channels act together in stimulating exocytosis. 3. The relationship between Ca2+ influx and exocytosis during the AP was examined using APs recorded from spontaneously active melanotropes as command templates under voltage clamp. Under voltage clamp, multiphasic Ca2+ currents were activated over the entire duration of the APs, i.e. during the rising phase as well as the plateau phase. The maximum amplitude of the Ca2+ current coincided with the peak of the AP. 4. The relationship between Ca2+ entry and exocytosis was linear for the different phases of the AP. Also, the influx of Ca2+ through LVA T-type channels stimulated exocytosis with the same efficacy as through the HVA channels. 5. APs of increasing duration ( approximately 50 to approximately 300 ms) evoked increasing amounts of exocytosis. The number of entering Ca2+ ions and the capacitance change were linearly related to AP duration, resulting in a fixed relationship between Ca2+ entry and exocytosis. 6. The results show that Ca2+ ions, entering a melanotrope, couple with equal strength to exocytosis regardless of the channel type involved. We suggest that the linear relationship between Ca2+ entry and secretion observed under physiological conditions (during APs), results from the equal strength with which LVA and HVA channels in melanotropes couple to exocytosis. This guarantees that secretion takes place over the entire duration of the AP.
This article was published in J Physiol and referenced in Journal of Cell Signaling

Relevant Expert PPTs

Relevant Speaker PPTs

Recommended Conferences

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

Agri, Food, Aqua and Veterinary Science Journals

Dr. Krish

[email protected]

1-702-714-7001 Extn: 9040

Clinical and Biochemistry Journals

Datta A

[email protected]

1-702-714-7001Extn: 9037

Business & Management Journals

Ronald

[email protected]

1-702-714-7001Extn: 9042

Chemical Engineering and Chemistry Journals

Gabriel Shaw

[email protected]

1-702-714-7001 Extn: 9040

Earth & Environmental Sciences

Katie Wilson

[email protected]

1-702-714-7001Extn: 9042

Engineering Journals

James Franklin

[email protected]

1-702-714-7001Extn: 9042

General Science and Health care Journals

Andrea Jason

[email protected]

1-702-714-7001Extn: 9043

Genetics and Molecular Biology Journals

Anna Melissa

[email protected]

1-702-714-7001 Extn: 9006

Immunology & Microbiology Journals

David Gorantl

[email protected]

1-702-714-7001Extn: 9014

Informatics Journals

Stephanie Skinner

[email protected]

1-702-714-7001Extn: 9039

Material Sciences Journals

Rachle Green

[email protected]

1-702-714-7001Extn: 9039

Mathematics and Physics Journals

Jim Willison

[email protected]

1-702-714-7001 Extn: 9042

Medical Journals

Nimmi Anna

[email protected]

1-702-714-7001 Extn: 9038

Neuroscience & Psychology Journals

Nathan T

[email protected]

1-702-714-7001Extn: 9041

Pharmaceutical Sciences Journals

John Behannon

[email protected]

1-702-714-7001Extn: 9007

Social & Political Science Journals

Steve Harry

[email protected]

1-702-714-7001 Extn: 9042

 
© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version
adwords