using a list to query - Mailing list pgsql-sql

I have a list (or array) of primary keys stored in a field (data type text).  
I would like to use the list to retrieve all the data from a table based on 
the list.

my text field contains:'123,134,343,345'

I would to do something like the following:

Select * from table1 where table1.pkid in (select myTextfield from table2)

So the question is there a simple way to use the list to retrieve my data?
-- 
John Fabiani