Embattled NAACP leader William R. Martin remembered going to a Riverbend Estates community meeting last November expecting to hear white parents complain about school busing in Prince George's County.

Instead, he heard a black woman complain about how her child was bused every weekday out of the intergrated neighborhood into a predominantly black elementary school seven miles away.

"I realized then," he said, "that a lot of water had gone under the bridge since 1973."

So when Martin was elected president of the Prince George's chapter of the NAACP in January, he decided to negotiate with school officials to alleviate the anger of parents whose children were being bused out of integrated neighborhoods into predominantly black schools under the 1973 mandatory busing plan.

But the agreement he reached last week with school board chairman Norman H. Saunders to reduce busing in integrated neighborhoods has caused, to Martin's bewilderment, some black parents and many NAACP members to charge betrayal and to clamor for their president's removal.

The dispute, more significantly, reflects the changing nature of the county's black population, the largely unchanged membership of the local NAACP and the uncertain role of Martin, a chemist suddenly shrust into the world of politics.

When Martin moved into his Chillum neighborhood in 1970, most county blacks were concentrated in inner-Beltway communities and nearly 60 percent of their childern atteneded predominantly black schools.

The busing plan, which came about after the NAACP joined a court suit, is based on those early 1970 demographics. But in the last six years, the county's black population had doubled, with many of the newcomers moving into previously all-white neighborhoods, such as Kettering and Riverbend Estates.

The 16-member executive board, most of whom have called for Martin's removal, is dominated by members who live in the inner-Beltway area and were active in the protests and court suit that led to mandatory busing.

Their fear over the agreement is that some schools might become segnegated once again.

Martin, though, referring to what he calls "the Glenarden and Seat Pleasant clique," said, "I'm supposed to be waving the baton, but it's the drummers who are leading the orchestra."

Martin, a 53-year-old chemist for the Food and Drug Administration, said his black constituency is "out there," but that "it deals in quiet diplomacy. It's not as loud as the county's old guard."

His constituency includes people like Rogers Davis, a Riverbend Estates area lawyer; Alton Thomas, a Kettering business manager, and Otis Ducker, an Ozon Hill resident and National Institutes of Health official.

"Bill's got more guts than anyone in the county right now," Ducker said. "He's out there on a limb, but if you take a poll of all the black folks in the county, you'll see that the jamority support him."

Martin, a light-skinned black whose red hair is flecked with white, remembered his youth in High Point, N.C., where he "hung out on street corners with (saxophone great) John Coltrane" and "went to blows with anybody who called me 'Red.'"

"I've always been sensitive to being called a 'Tom,'" he said. "One of my biggest fears (in reaching the agreement) was giving the impression of a Tom crawling up to the Great White Father. But I knew that if I talked it over with my executive board first they never would've agreed to it.

"So when the opportunity came up to do something about integrated neighborhoods, I felt the opportunity was worth the risk," he said.

He said the NAACP dispute is indicative of county wide cultural tensions between longtime black residents and more affluent blacks moving into the county's integrated areas outside the Beltway.

"It's a sad thing," he said. "Blakcs are attacked by other blacks just because they move up out of the slums into middle-class neighborhoods, or because their skin is lighter.

"To some extent, it's true that the more successful blacks become, the less invloved in politics they become," he went on. "And that's probably why I feel as alone as I do now, even though I'm not."

Martin said he regretted accusing school board attorney Paul M. Nussbaum of "duping" him into negotiations that led to the busing agreement.

"I've been involved in the NAACP since 1970," he said, "but this is the first time I've been in a position like this. You make mistakes.

"Perhaps 'deceived' would've been a better word. I didn't know the agreement would be as clearly drawn up as it was when I got to the last meeting (with Nussbaum, black leaders and school officials.)

"But I initialed it and don't regret doing it a bit," he said. "It's needed and I'll defend it to the ends of the earth."