As far as I know PR is all about internal and external linking, so I don´t see the way that content edition and updates on your site can affect your PR unless you decide to make a mess of your site. Some internal links tips I have found on this article are:

Make sure that your primary page(s), the index.htm page, links to your secondary pages or secondary levels.

•Make sure that your secondary pages link to each other •Link your secondary pages to the third level pages within their sub-directory, sub-domain, or level •Link the third level pages within each specific sub-directory or sub-domain to each other. •Link the third level pages back to the secondary page that it was linked from •Make sure that the there is not heavy linking between third level pages •Link to pages, regardless of level, that are relevant •Link to pages, regardless of level, where the text on the page being linked from is keyword specific to the page that you are linking to •If there are fourth level pages, follow the same linking structure that has been laid out in this checklist

Other reminders:

•Only link pages within your site that are relevant to each other •Use keyword specific link text when linking between pages •Use standard HREFs in links that are easy for the search engine robots.