I think you are looking for Preload Text Replacements perhaps?
Define and use a variable for "channels":
{preload_replace:channels="news|reviews"}
{exp:channel:category_heading channel="{channels}"}
<h1>{category_name}</h1>
{if category_description != ""}<p>{category_description}</p>{/if}
{/exp:channel:category_heading}
{exp:channel:entries channel="{channels}" limit="10"}
<h2>{title}</h2>
{body}
{/exp:channel:entries}