Changes in FAD and NADH Fluorescence in Neurosecretory Terminals Are Triggered by Calcium Entry and by ADP Production

Changes in FAD and NADH Fluorescence in Neurosecretory Terminals Are Triggered by Calcium Entry... We measured changes in the intrinsic fluorescence (IF) of the neurosecretory terminals of the mouse neurohypophysis during brief (1–2 s) trains of stimuli. With fluorescence excitation at either 350 ± 20 or 450 ± 50 nm, and with emission measured, respectively, at 450 ± 50 or ≥ 520 nm, ΔF/F o was ∼5–8 % for a 2 s train of 30 action potentials. The IF changes lagged the onset of stimulation by ∼100 ms and were eliminated by 1 μM tetrodotoxin (TTX). The signals were partially inhibited by 500 μM Cd2+, by substitution of Mg2+ for Ca2+, by Ca2+-free Ringer’s with 0.5 mM EGTA, and by 50 μM ouabain. The IF signals were also sensitive to the mitochondrial metabolic inhibitors CCCP (0.3 μM), FCCP (0.3 μM), and NaN3 (0.3 mM), and their amplitude reflected the partial pressure of oxygen (pO2) in the bath. Resting fluorescence at both 350 nm and 450 nm exhibited significant bleaching. Flavin adenine dinucleotide (FAD) is fluorescent, while its reduced form FADH2 is relatively non-fluorescent; conversely, NADH is fluorescent, while its oxidized form NAD is non-fluorescent. Thus, our experiments suggest that the stimulus-coupled rise in [Ca2+]i triggers an increase in FAD and NAD as FADH2 and NADH are oxidized, but that elevation of [Ca2+]i, alone cannot account for the totality of changes in intrinsic fluorescence. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Changes in FAD and NADH Fluorescence in Neurosecretory Terminals Are Triggered by Calcium Entry and by ADP Production

Loading next page...
 
/lp/springer_journal/changes-in-fad-and-nadh-fluorescence-in-neurosecretory-terminals-are-RvJHDssMhU
Publisher
Springer-Verlag
Copyright
Copyright © 2006 by Springer Science+Business Media, Inc.
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-005-0824-x
Publisher site
See Article on Publisher Site

Abstract

We measured changes in the intrinsic fluorescence (IF) of the neurosecretory terminals of the mouse neurohypophysis during brief (1–2 s) trains of stimuli. With fluorescence excitation at either 350 ± 20 or 450 ± 50 nm, and with emission measured, respectively, at 450 ± 50 or ≥ 520 nm, ΔF/F o was ∼5–8 % for a 2 s train of 30 action potentials. The IF changes lagged the onset of stimulation by ∼100 ms and were eliminated by 1 μM tetrodotoxin (TTX). The signals were partially inhibited by 500 μM Cd2+, by substitution of Mg2+ for Ca2+, by Ca2+-free Ringer’s with 0.5 mM EGTA, and by 50 μM ouabain. The IF signals were also sensitive to the mitochondrial metabolic inhibitors CCCP (0.3 μM), FCCP (0.3 μM), and NaN3 (0.3 mM), and their amplitude reflected the partial pressure of oxygen (pO2) in the bath. Resting fluorescence at both 350 nm and 450 nm exhibited significant bleaching. Flavin adenine dinucleotide (FAD) is fluorescent, while its reduced form FADH2 is relatively non-fluorescent; conversely, NADH is fluorescent, while its oxidized form NAD is non-fluorescent. Thus, our experiments suggest that the stimulus-coupled rise in [Ca2+]i triggers an increase in FAD and NAD as FADH2 and NADH are oxidized, but that elevation of [Ca2+]i, alone cannot account for the totality of changes in intrinsic fluorescence.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jan 1, 2005

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off