How to clear content in the update panel on dropdown selection change?

Question

<updatepanel1 >some conent</updatepanel1>

<updatepanel2 > Dropdown </updatepanel2>

I have a dropdown in update panel2, which gets some data from the database on the selection index change.

Sys.WebForms.PageRequestManager.getInstance().add_endRequest(endRequestHandler);
         function endRequestHandler() {
            $('select').change(function() { 
                    if(divMessage!=null)
                    {
                        divMessage.hide('slow');
                    }
                 }); 
                 $('select').click(function() { 
                    if(divMessage!=null)
                    {
                        divMessage.hide('slow');
                    }
                 }); 
         } 

On the click of the dropdown i am able to clear the content in the first update panel. But again on the selection index change of the dropdown, the cleared content is again coming back to the screen.

How to solve this???