Ag+ alters cell growth, neurite extension, cardiomyocyte beating, and fertilized egg constriction.
BACKGROUND
The Russian Space Agency uses electrochemically generated silver ions (Ag+) to purify drinking water for their space station, Mir, and their portion of the International Space Station. U.S. EPA guidelines allow 10.6 micromol x L(-1) Ag+ in human drinking water for up to 10 d. Studies correlate Ag+ exposure with tissue dysfunction in humans, rats, and mice, and with altered ion transport, skeletal muscle contraction, and embryonic cell constriction in other animal cells. Ag+ effects on cell shape change-related functions have not been assessed.


METHODS
Immortalized embryonic human intestinal epithelial cells, freshly explanted embryonic avian nerve cells and cardiomyocytes, and marine fertilized eggs were grown in vitro in medium containing AgNO3.


RESULTS
Intestinal cells detach from the substratum and viable cell number decreases by 5-6 d at 5 micromol x L(-1) AgNO3, and faster at higher concentrations. Microtubules appear unaltered in adherent cells. Detached cells are nonviable. Neurite outgrowth and glial cell migration from dorsal root ganglia are inhibited by 3 d at 15 micromol x L(-1) AgNO3 or greater. Contractions stop temporarily in most cardiomyocytes by 5 min at 5 micromol x L(-1) AgNO3 or more, but some cardiomyocytes beat 3 times faster than normal at 7.5-20 micromol x L(-1) AgNO3. Picomolar Ag+ increases marine egg polar lobe constriction within an hour, even in the absence of microtubules.


CONCLUSIONS
Ag+ alters animal cell growth and shape changes by a MT-independent mechanism. This is the first report of Ag+ effects on vertebrate neurite outgrowth, glial cell migration, or cardiomyocyte beat rate.
Conrad
A H
AH
Division of Biology, Kansas State University, Manhattan 66506-4901, USA. aconrad@ksu.edu
Tramp
C R
CR
Long
C J
CJ
Wells
D C
DC
Paulsen
A Q
AQ
Conrad
G W
GW
D000818:Animals; D002455:Cell Division / Q000187:drug effects*; D002478:Cells, Cultured / Q000187:drug effects; D002642:Chick Embryo; D004353:Drug Evaluation, Preclinical; D018504:Ecological Systems, Closed; D004847:Epithelial Cells / Q000187:drug effects; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology; D007421:Intestine, Small / Q000166:cytology; D051379:Mice; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D009206:Myocardium / Q000166:cytology*; D016501:Neurites / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D012835:Silver Nitrate / Q000009:adverse effects*; D013026:Space Flight; D018531:Spacecraft; D018508:Water Purification / Q000379:methods*; D015053:Zygote / Q000187:drug effects* / Q000502:physiology
D012835:Silver Nitrate