So I think I've got the countercurrent mutliplication system pretty much figured out in terms of concepts, but it all hinges on one detail which I can't seem to confirm via textbooks, google etc..
- Basically, at the end of the day, does the vasa recta just remove water from the medullary interstitium (as well as take some solute away but maintaing the gradient)?

So I think I've got the countercurrent mutliplication system pretty much figured out in terms of concepts, but it all hinges on one detail which I can't seem to confirm via textbooks, google etc..
- Basically, at the end of the day, does the vasa recta just remove water from the medullary interstitium (as well as take some solute away but maintaing the gradient)?

I think so, but if you add furosemide to the mix, eventually the vasa recta will "wash out" the medulla resulting in urine that's isotonic to plasma. Under physiological conditions the solutes that the vasa recta removes are replenished by the N-K-Cl-Cl cotransporter.

Thanks!