In more than 35 years of radio broadcasts, Don Imus has had run-ins with critics who have called him a racist, a homophobe, and mean-spirited. The targets of his brash humor have ranged from Asians to gay people, women to Muslims, but he always, it seemed, was able to walk away from a controversy unscathed.

There was a different tone in his voice yesterday during his nationally syndicated morning show, “Imus in the Morning.”

Not only did he spend much of his airtime giving a lengthy apology for describing the Rutgers University women’s basketball team as “nappy headed hos,” but he vowed to permanently change the nature of his show.

“Here’s what I learned: that you can’t make fun of everybody, because some people don’t deserve it,” Mr. Imus, 66, said. “And because the climate on this program has been what it has been for 30 years doesn’t mean that it has to be that way for the next five years or whatever, because that has to change.”

By day’s end, he had been grilled on-air by the Reverend Al Sharpton and suspended by MSNBC for two weeks starting April 16. (The radio show is simulcast on the television channel every morning.) At least one advertiser in the New York market, the insurance company Aetna, was planning to move its spots to other programs in response to the comments that Mr. Imus made, a spokeswoman for Aetna, Cynthia Michener, said.

“We found his remarks to be offensive and inappropriate, and we are redirecting our advertising to other programming,” Ms. Michener said. Other advertisers contacted by The New York Sun declined to comment.

One of Mr. Imus’s most vocal critics in the last days, Rev. Sharpton, said that he accepted Mr. Imus’s apology, but still wanted him to resign.

“You could be fired and the nicest guy in the world, but you ought to be fired,” Rev. Sharpton told him during a conversation on “The Al Sharpton Show.” Meanwhile, the Rev. Jesse Jackson rallied outside the headquarters of NBC in Chicago and called on the company to fire him.

The actual comments that Mr. Imus and the show’s executive producer, Bernard McGuirk, made last Wednesday took place over a matter of seconds. Speaking about the team Mr. Imus said: “That’s some nappy-headed hos there.”

The word “nappy” is a derogatory term used to describe the tightly curled hair of a person who is of African descent. It can also have connotations of uncleanliness and poverty, according to the Urban Dictionary, a Web site that tracks the meanings of slang words.

Mr. McGuirk went on to compare the championship game to a scene in Spike Lee’s 1988 satirical film “School Daze” where a dark-skinned team called the Jigaboos plays against a light-skinned team called the Wannabes. The sides call each other racially derogatory names in the film.

During his on-air conversation with Mr. Imus, Rev. Sharpton said: “I’m not going to call you a bigot. I’m going to say what you said was racist. I’m going to say what you said was abominable. I’m going to say you should be fired for saying it.”

Mr. Imus argued that it was “an ill-informed decision” to call for his resignation because people didn’t know what was “in his heart.” He described his volunteer work with children, some of whom are black, as proof that he is not a racist. Mr. Imus runs a ranch in New Mexico, the Imus Ranch, for children with cancer or sickle-cell anemia.

A spokeswoman for NBC Universal, Allison Gollust, said in a statement that the company’s decision to suspend Mr. Imus’s show “comes after careful consideration in the days since his racist, abhorrent comments were made.”

“Don Imus has expressed profound regret and embarrassment and has made a commitment to listen to all of those who have raised legitimate expressions of outrage,” Ms. Gollust said in the statement. “In addition, his dedication — in his words — to change the discourse on his program moving forward, has confirmed for us that this action is appropriate. Our future relationship with Imus is contingent on his ability to live up to his word.”

“Imus in the Morning” is syndicated in 70 stations and has been a platform for appearances by many politicians and authors over the years. Senators Lieberman, McCain, and Biden have appeared on the show. Aides to all three senators were unable to comment by deadline.

Mr. Imus is said to be paid in the eight-figure range; he has homes in Manhattan, Southport, Conn., and New Mexico. In New York, his show airs from 5:30 a.m. to 10 a.m. on WFAN, which is 660 on the AM dial.

While fellow radio host Howard Stern has publicly criticized Mr. Imus for racism in the past, he said he didn’t think that last week’s comments were enough his end his career.

“In terms of the things Imus says, this really isn’t bad,” Mr. Stern said on his show on Sirius satellite radio. “Imus will survive this.”