Effects of Freediving on your Kidneys

[Whopperhead]

(I'm sure this has been talked about BEFORE- Somewhere, but I am unable to locate a thread on it.)

At work we have a On Staff Nurse and he was asking me alot of questions about freediving and how long I hold my breath and so on. I know that alot of people in the medical profession don't understand freediving, but he insists that if I keep doing this I will eventually destroy my kidneys.

Does anyone have any info on the Good, The Bad and the Ugly about the effects freediving can have on your kidneys?

Side Note: This guy is a TOOL and I'd love to be able to come back to him with info- to shut him up.

He didn't believe me about dropping my heart rate- so he put a Pulse Oximeter (i think that's what it's called) on me and I started to do a breate up and a short breath hold and dropped my pulse down to 33. Which I thought I could get lower- But I was standing and it wasn't a long breathe up. But he was shocked by my 33- I commented "That's Nothing"

[octopus]

If you live long enough, you'll ruin your health.

He puts general statement, you have to go with explanation of gas-exchange theory and then he can give his objections? Hmmm, I do not like the concept.

I think he needs to be specific.

I can only guess that he aims at alkalosis/acidosis.
Perhaps this is good place to start:
Some notes on human acid-base physiology

4.3 The kidneys

The kidneys are responsible for the elimination of H+ and exert control over the concentration of HCO3-in blood. Based on the pH of the primary urine the kidneys can reclaim bicarbonate ions from the urine and return them to the blood, or they can allow them to leave the body. In the former case the excess protons leave the body together with another anion - usually phosphate. The phosphate/phosphoric acid pair is the main buffer in the urine. The kidneys are able to secrete H+ (by an energy dependent proton pump) against a concentration gradient of about 800:1 and consequently the urine pH may fall to 4.5. The kidney's ability to secrete an alkaline urine is very limited and the maximum pH is 7.8.
Although the ammonium/ammonia pair cannot function as a buffer in the conventional sense (pKa = 9.4), it plays an important role as a major vehicle in carrying protons in the urine. In a normal healthy adult about twice as much acid can be excreted at a urinary pH of 4.5 than would be the case if the ammonia mechanism were not present.

I like this one as it is simple (not strictly relevant to the topic, but good):
Human Physiology - Respiration

These are also not relevant for the topic, but they are interesting read:
http://www.bp.edu/Breathing_Chemistry.pdf
CO2 transport in FISH, as well as us lowly humans.

[Erik]

Ask him to cite his evidence. I can find a few articles about hypoxia and free radicals regarding kidney damage, but it's not about breath-holding.
He's got the academic training- he should put up or shut up.
Many academic professionals vaguely remember what they got taught, get it mixed up, and put it forth as empirically-researched fact. I believe it's a very human trait, but with that awareness, we should not be spouting things as fact or believeing them without some justification.
Nurses.... sheesh.

[cdavis]

Kind of like medical types saying that you can't increase your lung volume. Strictly true in a theoretical sense, but complete BS on a practical level.

Connor