[Zope] mysql connections in External Methods

I have an external method that opens its own connection to MySQL and performs a few reads and updates, then I close the connection. Apparently closing the connection does not really close things off as the connections are persistent. Eventually, I run out and things grind to a halt. Is there a way to force the connection to really die? (The obvious alternative is to either have a single connection which persists in the external method or to fetch the connection from Zope, either of which will work, of course.)