From University of Boon, BPA blocks calcium channels in cell membranes. Dangerous.

1. Bisphenol A: BPA Additive Blocks Cell Function
University of Bonn, Germany.
http://www.sciencedaily.com/releases/2012/12/121206094318.htm
http://www.inserm.fr/espace-journalistes/l-effet-nefaste-du-bisphenol-a-prouve-
experimentalement
Dec. 6, 2012 — Bisphenol A, a substance found in many synthetic products, is considered to be
harmful, particularly, for fetuses and babies. Researchers from the University of Bonn have now
shown in experiments on cells from human and mouse tissue that this environmental chemical
blocks calcium channels in cell membranes. Similar effects are elicited by drugs used to treat high
blood pressure and cardiac arrhythmia.
The results are now presented in the journal Molecular Pharmacology.
The industrial chemical bisphenol A (BPA) is worldwide extensively utilized for manufacturing
polycarbonates and synthetic resins. "This substance has been shown to affect the hormonal
system and may have negative effects on the function of enzymes and carrier proteins," reports
Prof. Dr. Dieter Swandulla from the Institute of Physiology II at the University of Bonn. BPA is
associated with heart disease, diabetes, obesity, cancer, and neurological dysfunction. "It seems
that fetuses and newborns are particularly sensitive to BPA," adds the physiologist. Due to its
unpredictable effects, the EU Commission banned the use of BPA in baby bottles in 2011 as a
precaution.
Bisphenol A blocks multiple essential calcium channels
The team of researchers around Prof. Swandulla now reports that BPA reversibly blocks calcium
channels essential for cell function in mouse and human cells. Calcium ions flowing through these
pore-like so-called channel proteins into living cells, control e.g. the contraction of heart muscle
cells, the activity of enzymes, and the communication of nerve cells with each other. "Drugs such
as those used to treat high blood pressure and cardiac arrhythmia on the one hand, and
neurotoxins, such as heavy metals, on the other hand act on exactly the same calcium channels,"
explains the physiologist from the University of Bonn. "This indicates that BPA can indeed have
adverse effects on human health." Since BPA binds to the calcium channels reversibly, there is at
least the possibility of the chemical being eliminated from the body.
Bisphenol A and its derivatives are ubiquitous
Nowadays BPA and its related substances can be detected almost everywhere in the environment.
Effective doses are found in CD's, paper money, thermal paper, food cans, dental fillings and flame
retardants, even in the breathing air and in house dust. Humans are meanwhile chronically
exposed to these compounds. "This is why it would be desirable to completely stop the production
of BPA," says Prof. Swandulla. "Due to the high-volume production and its widespread occurrence,
it would, however, take a very long time to remove this chemical from the environment and the
human organism." Consequently, alternatives to BPA should be utilized which are harmless to
humans and other organisms.

2. Bisphenol A Inhibits Voltage-Activated Ca2+
Channels in
Vitro: Mechanisms and Structural Requirements.
University of Bonn, Germany.
http://molpharm.aspetjournals.org/content/83/2/501
http://www.inserm.fr/espace-journalistes/l-effet-nefaste-du-bisphenol-a-prouve-
experimentalement
1. André Deutschmann,
2. Michael Hans,
3. Rainer Meyer,
4. Hanns Häberlein, and
5. Dieter Swandulla
+ Author Affiliations
1. Institute of Physiology II (A.D., M.H., R.M., D.S.), Institute for Biochemistry and Molecular
Biology (H.H.), University of Bonn, Bonn, Germany
1. Address correspondence to:
Dr. D. Swandulla, Institute of Physiology II, University of Bonn, Nussallee 11, 53115 Bonn,
Germany. E-mail: dieter.swandulla@ukb.uni-bonn.de
Abstract
Bisphenol A (BPA), a high volume production chemical compound attracts growing attention as a
health-relevant xenobiotic in humans. It can directly bind to hormone receptors, enzymes, and ion
channels to become biologically active. In this study we show that BPA acts as a potent blocker of
voltage-activated Ca2+
channels. We determined the mechanisms of block and the structural
elements of BPA essential for its action. Macroscopic Ba2+
/ Ca2+
currents through native L-, N-,
P/Q-, T-type Ca2+
channels in rat endocrine GH3 cells, mouse dorsal root ganglion neurons or
cardiac myocytes, and recombinant human R-type Ca2+
channels expressed in human embryonic
kidney (HEK) 293 cells were rapidly and reversibly inhibited by BPA with similar potency (EC50
values: 26–35 μM). Pharmacological and biophysical analysis of R-type Ca2+
channels revealed that
BPA interacts with the extracellular part of the channel protein. Its action does not require
intracellular signaling pathways, is neither voltage- nor use-dependent, and does not affect
channel gating. This indicates that BPA interacts with the channel in its resting state by directly
binding to an external site outside the pore-forming region. Structure-effect analyses of various
phenolic and bisphenolic compounds revealed that 1) a double-alkylated (R-C(CH3)2-R, R-
C(CH3)(CH2CH3)-R), or double-trifluoromethylated sp3
-hybridized carbon atom between the two
aromatic rings and 2) the two aromatic moieties in angulated orientation are optimal for BPA’s
effectiveness. Since BPA highly pollutes the environment and is incorporated into the human
organism, our data may provide a basis for future studies relevant for human health and
development.
Footnotes
• dx.doi.org/10.1124/mol.112.081372.
• Received July 26, 2012.
• Accepted November 29, 2012.
• Copyright © 2013 by The American Society for Pharmacology and Experimental
Therapeutics