Yes the rat scene inthe movie was real. The rat in question was one of a group that was used during the animal testing process. This theoretical science is not new. in fact it was proposed and tested on small animal in the sixties. In the first few years of the experiment, every rat died of lung damage shortly after being drainned.
In the last few years (yes they've been experimenting with this stuff for over 40 years), they have managed to keep the rats alive, but human testing (dont know about the military they tend to do t'hings their own way, and in their own time) has not been undertaken as there is permanent damage done to the alvola, and broncheal tubes.
The public word, from the authors of the studies, is that, at this time, liquid breathing technology is potentially viable, but the after effects of prolonged, and repetitive exposre are fatal. (even in the rats....too many time down = death)
There has been some interesting work done using the medical applications of this technology, but it is still considered a risk treatment, and is not commonly used.
By the way for those who bought into the line from the movie (we all breathe liquid for nine months) that's another hollywood fantasy. Unborn children get their air supply from the umbillicp cord. The heart of the unborn cjhild has a valve that allows oxegenated blood to bassically by pass the lungs as they lungs are not functional. Just do a search on PFO and diving and you'll see where the nonclosing of that little valuve has been atributed to some cases of DCI.
All of this can be found with a simple evening surf of the web. It's not new, but it mae fr a good evening's read on a cold winter night a few months ago.
