The Senate took a step toward curtailing the powers of the Federal Trade Commission yesterday, even as that normally combative agency was doing some retrenchment of its own.

The Senate voted to suspend any new regulations issued by the FTC for up to 80 days to give both houses of Congress time to override them. But it then defeated, 44 to 53, a one-house veto that would allow either body to kill any FTC regulation independently.

President Carter had said he would "strenuously" resist a bill containing such a provision.

Then, voting 45 to 47, it rejected a proposal to prohibit the FTC from investigating or regulating legal, medical or other selected professions under antitrust and consumer protection laws.

Perhaps in anticipation of the Senate votes, the FTC, which has been under broad attack by business groups for more than a year, said yesterday it was cutting back a 4-year-old antitrust investigation of the auto industry.

It also indicated that it will move more cautiously than its staff had proposed in limiting the control that doctors have over Blue Shield health insurance plans.

But many senators, saying the public is fed up with regulation in general and the FTC in particular, were plainly gunning for the agency.

In its first vote on a dozen or more amendments curbing the agency's authority, the Senate decided, 87 to 10, to suspend future FTC regulations for up to 80 days to give Congress, both houses acting jointly, time to overrule them.

This so-called "two-house legislative review" was offered as an alternative to the even more restrictive one-house veto that was included in an FTC bill passed by the House last year.

On the other-house veto proposal, Virginia senators voted in favor, while Maryland senators voted against.

The bill as reported by the Senate Commerce Committee already contains some restrictions. Sen. Wendell H. Ford (D-Ky.), a sponsor, said the aim was simply to make the commission, created in 1914 to encourage competitive and fair business practices, back into a "responsibile and respected agency." Opponent Howard M. Metzenbaum (D-Ohio) countered that the aim was to cripple the government's main agency for protecting consumers.

As approved by the Commerce Committee, the bill would bar the FTC from investigating the insurance industry, halt its proceedings against television advertising aimed at children and limit the scope of any future commerical advertising actions, ban requirements for used car warranties, curtail rule-making for voluntary production standards set by private groups, curb the commission's broad investigative authority and stop disclosure of financial data submitted by companies on matters such as pricing policies, testing and advertising.

Other possible floor amendments would exempt legal, medical and other professions from FTC investigations for two years, prohibit the commission from enforcing antitrust laws on agricultural cooperatives (as the House bill does) and halt the FTC's proceedings on sales and servicing of mobile homes.

Before the Senate debate opened, the five FTC commissioners announced that they had ordered their staff to narrow the scope of the auto investigation and to drop subpoenas they had issued demanding information from U.S. automakers.

The commission said the action was taken "As a result of information obtained during the inquiry and recent changes in the industry, including the financial weakness of Chrysler, rising fuel prices and increased sales of imported cars."

The auto industry investigation was started to study why the U.S. car business has become dominated by General Motors and Ford. The FTC offered no explanation of why the threatened failure of Chrysler made that question less important.

One spokesman said the FTC was "narrowing the scope, but sharpening the focus" of the auto probe.

The car makers had strenuously resisted the investigation, saying it would cost them millions of dollars to provide all the information the FTC was asking for. The scope of the probe had already been scaled down once.

The decision to cut back on the car business study came only a day after the FTC appeared to back away from an attempt to limit the control of doctors over Blue Shield and other medical insurance plans.

Last year the FTC staff recommended that doctors be prohibited from controlling the boards and committees that oversee health insurance plans. Critics complained that doctors have conflict of interest with efforts to cut medical costs, including their own fees.

Rather than take on the doctors directly, the commissioners, led by Chairman Michael Pertschuk, voted to seek comments on whether any action is needed to limit docotr's control of health plans. olence.

In the search, "I saw baseball bats and all kinds of stuff falling out from under their coats and pants," said Jim Baca, a spokesman for the governor who watched through binoculars from the prison command post.

Last night, inmates flooded floors and set fires in a cellblock to protest conditions in the burned-out prison.

Officials said they would comply with the request by the black inmates to be kept separate.

"The blacks who elected to stay out (in the yard) will be transported" to the former women's quarters, Baca said. "Quite a few of the blacks will be transferred to other state prisons."

Anthropologists checked for more bodies in the ashes of the still smouldering prison gymnasium and authorities investigated rumors of more reprisal killings in the aftermath of the 36 hours of violence.

"We haven't seen any more bodies out there," said State Police Capt. John Dickson. "We think these rumors are mostly inmates boasting to Nation Guard troops or guards standing outside the yard."

Inmates were prepared for transfer to other state and federal prisons around the country. Officials tried to segregate troublemakers from low-security risks and from prisoners who might testify about the carnage and killings.

"Some of them obviously fear reprisal if they are housed with the inmates who participated in the uprising," Gov. Bruce King said.

Last night's flood and fires occurred "in a cellblock where we put some of the heavies," said Corrections Department spokesman Joann Brown. "It involved maybe a couple of cells. We are breaking them up. These are some of the ones being transferred out of state now."

Some inmates did their best to confuse authorities trying to identify bodies and classify the survivors yesterday. Many gave false names others refused to give any name and some may have been counted twice.

Officials said inmates today were "cooperating much better and they're pretty calm."

A former warden of the institution, Clyde J. Malley, had warned almost two years ago of the dangers of overcrowding the prison.

"It is going to burst at the seams until the inmates burn it down to get attention" about overcrowding, Malley told UPI in a March 1978 interview two weeks after he was fired.

District Attorney Elroy Martinez said charges probably would not be filed for several weeks because of the problem of matching offenses with inmates. He said charges likely would include murder, kidnaping, criminal sexual offenses, intent to incite riot, conspiracy to riot and vandalism.

Families desperate for word about the fate of inmates became unruly outside the gates yesterday and shouted down the warden.

"We want the whole truth and not just part of it," a man said. "Don't lie to us. We're tired of being lied to."

State police pushed and shoved some in the crowd of about 75 people to clear a narrow two lane highway in front of the prison. National Guard troops formed a supporting line behind the policemen, and nervous police dogs on leashes bared their teeth and barked at the crowd.