HELP! Getting low yields from RNA isolation kit

[cem418]

Hi Everyone,
I am trying to isolate RNA from whole rat blood using the PreAnalytix (QIAGEN) Blood RNA kit from PAXgene tubes. Unfortunately, some of the samples make these really stubborn, large pellets that won't break up no matter how much I vortex them. The issue is that if the pellet isn't completely broken up, the RNA is kept in the pellet and I get a low yield. I have tried using a sterile transfer pipette to break up the pellet, which does break it up, but then I think it degrades the RNA because I get even lower yields.

PLEASE HELP ME! I am out of ideas! Especially if you have experience isolating RNA from whole blood in rats or WKY rats please let me know.

Thanks so much!

[JamieHeather]

I only use the RNA that comes off PAXgene tubes (or similar) but I remember a discussion with people talking about the importance of mixing well/leaving long enough to allow complete lysis.

Do you know how the blood's being treated immediately after putting it in the tube?