"Ahhh, mayor," said Mstislav Rostropovich, grasping Mayor Marion Barry by the shoulders and kissing the mayor on each cheek.

It was the way the maestro, jubilant after his opening night concert of the National Symphony Orchestra, greeted everyone at the reception last night in the Atrium of the Kennedy Center. He kissed everyone several times each, he shook hands strongly, he cooed over everyone -- and there were many crowded around him at last night's party.

"Yes, I am excited about the start of the new season ," he said. He had traded his black tails for a maroon, velevet jacket, and he held a glass of white wine. "I am excited always." He threw back his head and laughed devilishly.

It seemed far from his mind that season subscriptions for the symphony have lagged, and that even on opening night there had been a sprinkling of empty seats. As late as yesterday, phone banks were still set up to ask people to buy subscriptions.

"We were behind," said Austin Kiplinger, chairman of the symphony board, "but I suspect with the opening of the season you will see a surge in subscriptions this week."

The crowd overflowed into the Atrium with such guests as Rep. Sidney Yates (D-Ill.), Peggy Cooper, chairman of the D.C. Commission on the Arts and the Humanities, commission executive director Mildred Vautista, and Patrick Hayes, managing director of the Washington Performing Arts Society.

"I'm a sucker for Rostropovich," said Roger Stevens, chairman of the board of the Kennedy Center. "He's got such personality."

Stevens said calmly that he heard very little in reaction to the surprising move of Martin Feinstein from his executive directorship of the Kennedy Center.

"I think it's absolutely fascinating that we had discussed that move at an executive meeting two weeks ago and nothing got out until yesterday," said Stevens. He was reminded of the rumors that noted he had conflicts with Feinstein. Stevens shrugged and then spotted Feinstein and his wife walking past.

"Did we have any personality conflicts?" Stevens asked Feinstein.

"Absolutely," said Feinstein, grinning slyly, "you can see that," Feinstein walked on.

Also attending were some of the Kennedy Center's trustees from New York, including T. Vincent Learson, who told Rostropovich he would be taking a trip to the maestro's native Russia. "I hope you're not defecting from America to Russia like my compatriots did the other way," quipped Rostropovich.

Learson is the organizer of the New York Insurance Exchange, modeled on Lloyds of London, which he called "the hottest thing in New York."

Later, Rostropovich presented frame pictures to two retiring members of the symphony, cellist Franz Vlashek and percussionist John Kane, praising them highly. He also presented a birthday cake to Kiplinger, whose birthday is today. Then he led the room in a chorus of "Happy Birthday."

"I've never heard a song with better musical direction," said Kiplinger.