How to change the font-weight Bold to normal with out refreshing the grid

Hi,
i am opening the grid row with double click event.
first time its in "Bold".after double click i want to change the row font-weight to "normal".color its changing like this..
obj.getTemplate("row",rowid).setStyle("color", "red");

can anybody please suggest how to change the font-weight "bold to "normal"

yours