NEW YORK — Julie Kantrowitz has been upped to senior VP, media sales, the top ad-sales post at Warner Bros. Domestic Television Distribution.Since 1994, Kantrowitz, a 12-year Warner Bros. veteran, has been VP-general sales manager, media sales. She’ll now be responsible for all barter ad sales of firstrun and off-network syndication properties of WBDTD and Telepictures Distribution, including “The Rosie O’Donnell Show,” “Jenny Jones” and “Extra” as well as “Martin,” “Step by Step” and, for its fall 1998 syndication launch, “Friends.” She’ll also sell ads for Warner Bros. Online. In her new Gotham-based post, Kantrowitz succeeds Clark Morehouse, who joined K-III’s Channel One as exec VP, East Coast sales and marketing. Kantrowitz reports to Dick Robertson, WBDTD’s president. “I can think of no more effective or deserving person to take charge of running this critical revenue-generating division than Julie,” Robertson said in a statement. Before joining the studio in 1985, she worked at NBC and ABC in various posts.