This is interesting (potassium regulation...)

[visceral_instinct]

You get "hyperkalemia" during exercise, but it isn't dangerous as it would otherwise be if you were at rest.

During extreme exercise, potassium is released from active muscle and the serum potassium rises to a point that would be dangerous at rest. For unclear reasons, it appears as if the high levels of adrenaline and noradrenaline have a protective effect on the cardiac electrophysiology.[5]

Taken from http://en.wikipedia.org/wiki/Hyperkalemia

Recent studies suggest that increases in catecholamines during exercise are cardioprotective to the arrhythmogenic effects of hyperkalemia.

...

(http://www.sciencedirect.com/scienc...serid=10&md5=9ce738bcb095af00a48d08faee6d1cda)

I'd love to know why that is.

 

[Michael]

There are two different cells in the heart. Pacemaker cells and contractile cells. The catecholamines can effect these cells in different ways. My guess is it probably effects the opening or closing of voltage gated K channels. But, to tell you the truth, there's a lot of physiology in there

 

[edenocp]

plenty of nerve and cell to cell tranmission of electrical signaling would be utilizing these hormones along with the need for more potassium in blood