As Marion Barry descended the curved staircase in the Sheraton Washington Hotel for a reception Wednesday night, many of the nattily dressed physicians and dentists seated below put aside their white wine and hors d'oeuvres and hastily lined up to shake his hand.

Four years ago, candidate Barry was anathema to many in the city's established black middle class, who viewed him as an unsophisticated embarrassment trying to hustle his way off the streets and into respectability.

Now, running for reelection, Barry was debonair in a dark-blue two-piece suit. His elegantly attired wife Effi was at his side, and Barry moved with confidence among the black elite. Like some other women present, he noted at one point, Effi Barry was a member of the prestigious Delta Sigma Theta national black sorority. As for himself, he was the mayor.

"I love to surround myself with people as smart or smarter than myself," Barry told the blushing crowd of more than 200, reminding them that he, too, had studied chemistry in college.

"The next time you're treating patients, ask them who will they vote for on Sept. 14," he added. "If they say Marion Barry, fine. If not, let them lay there for a while." The audience chuckled.

Using his power to appoint health-care commissioners and advisory board members and in some instances, improve business for the medical and dental professions, Barry has become a hit among crowds like this one, whose support has given prestige and money to his campaign.

Conventional wisdom held that this should have been a crowd for candidate Patricia Roberts Harris--a lawyer, former Carter administration cabinet member, onetime Delta national director, and Howard University graduate who is Barry's leading challenger in the Sept. 14 Democratic primary.

Or it should have been a crowd for candidate Charlene Drew Jarvis, a native Washingtonian trained as a research scientist whose late father, surgeon Charles R. Drew, developed the modern blood bank and is a standard figure in most black history lessons. Improving health care in the city is a major theme of City Council member Jarvis' campaign for mayor, and she represents the ward where many in this audience live.

But this prime cut of black elite, carved in part from the voter-rich Wards 4 and 5 in upper Northwest and Northeast Washington, belonged to the incumbent.

"What I thought about Barry in 1978 is no longer relevant," said Roy L. Baptiste, a dentist who supported then mayor Walter E. Washington four years ago. "Look at Marion now. We have had time to see the man and be part of his team. He's matured and he's definitely in charge."

Jim Sheppard, an internist, said he has heard Barry criticized as an inarticulate speaker. "I don't care if he splits five infinitives," Sheppard said. "What's important is his actions, not his words."

Jesse Barber, a neurosurgeon and past president of the predominantly black National Medical Association who supported Sterling Tucker's candidacy in 1978, said, "This is not an anti-Pat Harris group, it's pro-Barry. Marion has the broad appeal that's necessary to make the city work. He can relate to my patients at 14th and T Streets as well as my neighbors on North Portal Estates," an affluent section of upper Northwest.

Barry's record on health care has been mixed since he became mayor in 1979. Early in his administration, he declared infant mortality the city's No. 1 health problem. In 1979, the infant mortality rate went down, only to rise again slightly in 1980. Figures for last year have yet to be released.

Between 1980 and 1981, the city's tuberculosis rate, for years one of the highest in the nation, dropped by 30 percent, according to a Barry report whose findings have been questioned by some physicians. Barry's budget cuts closed the Upshur Street Clinic.

Contracts he signed recently that won praise--and political support--from city employe unions representing several thousand workers included long-sought provisions for free optical and dental care.

"He has done some things that have upset the health community, but he has done more things that they approve of," said Sheppard.

The 147 physicians and dentists who sponsored Wednesday's affair raised more than $5,000 to pay for the event, designed more as a show of support than a fund-raiser for Barry, who already has raised nearly twice as much money as any other political candidate in the city's history.

Barry's opponents had mixed responses to the event. Two of the nine cochairmen of the Harris campaign are doctors Roselyn Epps and Pearl Watson. "I'm surprised that anyone would choose Barry over Harris," said Watson, outgoing president of the city commission that licenses physicians. "I am disappointed that people of vision would support someone who has neither the formal training or the talent to promote the advancement of this city's health and education."

Epps noted that there were more than 3,000 doctors and dentists in the area, and said that those on hand at the Barry dinner were only a fraction of that amount. "I'm sure Mrs. Harris has many more supporting her," Epps said.

Jarvis said yesterday that the group's support for Barry could not be based on the incumbent's record. "The Barry administration has given the lowest priority to health-care delivery of any of the services in the city," she said, adding that D.C. rates for venereal disease, infant mortality, tuberculosis, alcoholism and drug addiction were "unacceptably high."

"The support of some members of the medical community must therefore be understood in terms of their own personal economics rather than in terms of the priority given to health by the Barry administration," Jarvis said.

Candidate John Ray, a member of the City Council, declined comment on the Barry event.

The doctors who said they support Barry also cited his efforts to cut red tape for them when a building permit for the National Medical Association and American Medical Association headquarters was bogged down in the District's sluggish bureaucracy.

For the doctors' part, they have been criticized in the past by neighborhood activists following in Barry's footsteps who said the physicians refuse to locate their offices in impoverished areas like far Northeast and Southeast Washington, where the need for improved health care is greatest.

However, Dr. Arthur Hoyte, Barry's appointee as D.C. commissioner of public health, said, "There are a fair number of doctors who would move into Anacostia and I think the mayor will enhance their move with incentives."

Stanley Boucree, president of the National Dental Association, summed up the support for Barry this way: "Simply put, we believe in going with a winner."