How can I display and hide a second line of text underneath this, just by pressing, say an arrow next to the first line?

Example of "closed" item:

> John Doe, Calcutta

Example of "open" item, after arrow is pressed:

^ John Doe, Calcutta
  21. jump street, PO box 242

Is it possible to do this in a way that is compatible with older browsers, like NN4 ?

Place it in two div tags and on click of the > change the image to ^ and make the second div as visible and first one as hidden.
But DIV is not supported in NN4.It is supported by NN6 and above..