Nope. Again, PageRank is ONLY determined by the number and quality of links pointing to the page. Alt tags, like body text, title tags, h1 tags, etc. help Google determine the content of the page. Keep in mind that PageRank is just one, relatively minor factor in determining where a page will show up in search results. Those other factors often have a much bigger impact.
To put it another way... The only way you can increase PageRank is by getting more or better links pointing to the page. You can improve your positioning in search results a great deal, however, by making sure your title tags, alt tags, h1 tags, etc. accurately describe the content of the page with the keywords that people will be searching for. That said - don't try to trick GoogleBot with keyword spamming, since that may work for a few weeks or months, but might eventually get you banned from Google's index altogether.
If you want to know how PageRank works from a mathematical perspective, you might take a look at:
http://www.iprcom.com/papers/pagerank/
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