http://forums.steroid.com/showthread.php?t=199822
This is a quote from it.
Since we’re speaking about beta-receptors and upregulation, here, let me address the claim that you can use ephedrine (or the ECA stack), alternating with clen, in order to avoid receptor downgrade. I’m not sure where this rumor came from, but it is totally incorrect.
To dispel this myth, lets examine ephedrine for a second. Remember when I said that using clenbuterol to stimulate the beta-2 receptors is like hitting a tack with a hammer? Well, Ephedrine is like a sledge-hammer, it hits the beta-2's and everything around them. Thats because it's not selective, but rather it stimulates other receptors to a great degree as well.
Anyway, one of those receptors that ephedrine hits is the Beta-2 (yeah...the same one as Clen). As you can see from the graph below(ephedrine is represented by the the solid circles), it reduced Beta-2-AndrenergicReceptor (what we call, in laymens terms, the "Beta-2 receptor") levels to 32% of the control level after 24 hours. Read this again:
Granted, it's not perfect, it's not in vivo, etc...but there's no denying that ephedrine will downregulate beta-2 receptors....ergo you will not be able to use it on the weeks inbetween your clen to upgrade your receptors.
Here is another link to Beasts Clen facts.
http://forums.steroid.com/showthread...highlight=clen