RNA / nothern blotting question

[Lana C Stallard]

I have some questions for anyone out there who is doing northern 
blotting. What is the accepted method (for publishable results) 
for loading equal amounts of polyA RNA (or total RNA) onto a gel? I 
can use a spectrophotometer to approximate the amount, but from what i 
understand that tends to be inaccurate. I am about to begin using a 
B-actin probe to "normalize" the RNA amounts after hybridization. Is this 
the accepted way of verifying that your treatment truly caused a change 
in the amount of mRNA, not that if is a generalized protein effect or 
that the amounts of RNA loaded are causing the differences if probe 
binding?
Any advice, comments or improvements to this technique? Thanks LS