D.C. Mayor Marion Barry was transferred yesterday from the coronary unit to intermediary care at Howard University Hospital and doctors upgraded his medical condition from "guarded" to "stable" after two days of tests and treatment.

"The mayor is fine and there is no evidence he had a heart attack, nor does he have heart problems," Annette Samuels, Barry's press secretary, said after conferring with the mayor's doctors. "They will continue monitoring him, but he's not in the coronary unit."

Barry, 47, was rushed to the hospital from the Washington Hilton Hotel early Sunday after he complained of difficulty breathing and sharp chest pains. Although the chest pains later subsided, the mayor was kept in the coronary unit for 48 hours while he underwent tests for everything from a possible heart attack to serious stomach disorders.

Samuels, who has handled inquiries about the mayor's condition, said electrocardiograph and "cardiac enzyme" tests administered to Barry failed to uncover evidence of a heart attack or heart damage.

Barry, who was bedridden until yesterday, has not yet undergone stress tests that might indicate whether the mayor is suffering from a heart disease.

Doctors have yet to agree on what caused Barry's problem, but according to one source at the hospital, "exhaustion played a big part of it."

Barry spent Friday and Saturday at the Washington Hilton participating in the 13th Annual Congressional Black Caucus legislative weekend, including a reception in his room that went well past 3 a.m. Sunday.

Samuels, who attended the reception, said the mayor drank a moderate amount that night and, to her knowledge, hadn't used any medication.

Asked whether the blood test taken upon Barry's arrival at the hospital had provided any clues, Samuels replied that it had not.

Barry was visited yesterday by his wife, Effi, City Administrator Thomas Downs, Clifton Smith, the mayor's staff director, and Samuels. Downs brought along some papers for Barry's review and signature.

Samuels said Barry got out of bed twice yesterday to walk around. "He said he felt fine and was ready to go home."

Barry is expected to remain in the hospital at least until the weekend.