Conservative radio host Rush Limbaugh, who was hospitalized on Wednesday with chest pains and held for tests and observation, was released from Queen’s Medical Center in Honolulu on Friday. In a news conference, Limbaugh, who had been vacationing in Hawaii, said that doctors had found nothing wrong with his heart and that the cause of his symptoms was unknown. “The pain was real, and they don’t know what caused it,” he told reporters. Premiere Radio Networks, which syndicates Limbaugh’s show, said in a statement that he will return to his hosting duties “sometime next week, after some rest, but will make appearances with fill-in hosts in the early part of the week.”