Re: Does excess water in cells cause them to breakdown over time?

Marshal:

There are two aspects to your question, the first is a correction on your 
perception of salinity, the second is what would happen under the 
circumstances.

The process you are describing in general is osmosis, which has been 
reviewed in several other postings on Madsci.  You can find the links 
below:
 http://www.madsci.org/posts/archives/2002-02/1014825690.Cb.r.html
 http://www.madsci.org/posts/archives/2006-05/1147190392.Cb.r.html

However, the process of osmosis here will be counterbalanced somewhat by 
diffusion, which is the passage of a solute from high concentration to 
low.  In this case 9% saltwater is not at all close to any common 
physiologic salt concentration.  Perhaps you meant 0.9%, which is the 
typical salt concentration of mammals.  Ocean salt water is about 3.5% 
salt.  The solution you describe will tend to severely dehydrate cells 
that are placed into it.  In particular the plant cells, the membrane will 
shrink inside and pull away from the cell wall.  This is in fact 
observable under relatively low-power microscopy with something like a 
thin section of onion skin.

If you placed the samples into a hypotonic solution, like distilled H20, 
the cells could in fact degrade (break) over time.  The water would cause 
solutes to rush out of the cell, replacing them with distilled water and 
the cells would swell, and some percentage of them would break.  The 
carrot would be substantially more resistant to this as its cells are 
protected by a cell wall, something the cells in the liver do not have.

The simplest set of experiments to observe this phenomenon involve soaking 
eggs in venegar for several days to remove the shells and very carefully 
placing them in things like corn syrup (virtually no water) to distilled 
water (all water)... You can then watch the egg swell and shrink 
accordingly.  

Good luck, diffusion and osmosis are great researh (and topics of 
question) in general.  Cells do a lot of really counter-intuitive things 
when confronted with environments that are hostile to stability.