Influence of cystic fibrotic and heterozygous serum on rat jejunum.

The rat jejunum bioassay has been shown to be capable of identifying 
both the cystic fibrotic homozygote and heterozygote and therefore would appear 
to have great potential as a screening test for the latter. 
It is suggested that the cystic fibrosis factor does not influence 
sodium reabsorption by inhibiting an active sodium reabsorption mechanism but rather 
by inhibiting passive sodium entry into the cell. 