Thank you, Hany, for your kind introduction.

What I will try to do is give you sort of an overview of potassium transport, a topic

that I've been quite involved for quite a number of years.

And to start out, we'll go to the first slide.

I will structure my presentation a little bit

like indicated here, saying something

about the nature of the physiological challenge

that particularly rests on the very peculiar distribution

of potassium in the body that will

lead to a consideration of internal and external potassium

balance.

And then I will focus on a couple aspects

of renal transport mechanisms that

has been a topic of my interest for many, many years.

Here is an overview of the distribution of potassium.

On the left, the cellular compartment.

On the right, the dietary intake and the gastrointestinal tract.

Obviously, potassium enters the body

by transfer from the extracellular fluid, the stomach,

into the cellular compartment.

And then there's a sort of dynamic equilibrium

between extracellular potassium, a small amount

to various organs.

And the influx and efflux errors indicate the main factors

that either lead to increased cellular uptake

or to enhanced efflux into the extracellular fluid.

Hyperkalemia obviously leads quite often

to at least temporary transfer from potassium

into the cellular pools, as indicated on the left.

Acid base balance is a regulatory factor

with alkalotic conditions, again,

favoring uptake of potassium.

The adrenergic systems have acute effects

on potassium distribution, as indicated.

And you're familiar, I'm sure, with insulin as well.

Although Stern has always been a little bit more questionable,

it's not as easy to demonstrate.

But I think the balance of evidence

now favors the view that higher aldosterone has

an effect on potassium uptake.

In the upper quarter angle, you see

there's important factors, particularly

sedatic conditions that lead to influx.

And strenuous exercise can lead to considerable swings

in extracellular potassium by enhanced efflux.

Here, I wish to just show you the different time

course of the two main factors regulating potassium transport.

If there is an intake of potassium,

you have two types of responses, essentially.

Hormonal-immediated K-translocation