Actionscript 3 :: Combine Multiple Variable Names Together To Target New Variable

I'm still learning flash and actionscript 3 and i am having trouble with variable and object names. I need to be able to combine variable names together (in the same way as php can combine by doing var1.var2).

My swf contains 4 loaders (image1_loader, image2_loader etc..) which are a child of (image1_content, image2_content etc.....)
I then have 4 buttons which load an image into the loader and while doing so they define the currently active loader.
Finally i have 4 control buttons - scale up/down and rotate clockwise/anticlockwise which should only control the currently active loader (as set by the buttons above)

So my buttons as well as loading the image have the event listener:

image1_btn.addEventListener(MouseEvent.CLICK, setCurrentSelection);
image2_btn.addEventListener(MouseEvent.CLICK, setCurrentSelection);
(and so on..)
function setCurrentSelection(e:MouseEvent):void {

[Code]...

So within the rotateClockwise and rotateAntiClockwise functions i need to be able to recognise which is the currently active loader and have that number instead of the X - so if it is image1_loader - it needs to be image1_content, if 4 - image4_content... I had tried to do it as this but it doesn't like it being a string:

rotateAroundCenter((activeLoader+'_content'), 10, ptR);