Potassium levels and metoprolol

There seems to be conflicting information out there regarding how metoprolol (and selective beta blockers) effect potassium levels in the blood... I know that non-selective BB can raise levels, but not sure how selective BB effect potassium levels.

The reason I ask is that I like to have a high-potassium diet to control my palpitations, but wonder if I need to be careful how much I intake... My doctor has never warned me to watch how much fruit I eat, but some articles on the internet seem to indicate a link between metoprolol and high potassium levels.  

My blood tests have always been normal, but it still concerns me.

[curmudgen]

I can't find the source of my information but I remember reading that metoprolol is potassium sparing drug - meaning it doesn't cause potassium levels to drop.  I don't believe that consuming fruit with a high K diet alone would raise K values to the point of side effects.  At the moment I am more interested in the magnesium deficiency/arrhythmia information that I have read about.  There seems to be something to that side of the electrolyte balance.  I asked my pharmacist and he recommended magnesium chloride supplement.  I will try anything to avoid the palpitations.  

[Madge270]

My doctor told me recently that people taking acid reflux meds (such as Nexium or Prilosec) need to know that those drugs also cause magnesium deficiency! What next?