Henle's Water Music
by Greg Crowther
Where osmolarity is high
In the renal interstitium,
That's where water will diffuse
If the pores are in position.
So when ADH is high,
And it's water that you're missin',
Aquaporins in the duct
Lower water loss from pissin'!
This song covers the mechanism by which water is conserved in mammalian kidneys. In brief, the nephron's loop of Henle maintains an osmolarity gradient such that, when pre-urine travels down the collecting duct, water is drawn out of the collecting duct into the interstitial fluid and reabsorbed by the blood. This reabsorption is greatly enhanced by the insertion of water pores (aquaporins) into the membranes of collecting duct cells, which is caused by the release of antidiuretic hormone (ADH) during periods of dehydration.
The rising melody of the lines "Where osmolarity is high" and "So when ADH is high" provides musical reinforcement of the idea that, in the scenario of the song, these parameters are indeed high.