Eight congressional wives began lobbying on Capitol Hill yesterday to undo what they called the "shocking" attempt by some of their husbands' colleagues to interfere with a Federal Trade Commission inquiry into television advertising aimed at children.

Four representatives of the group personally distributed a letter to members of the House Appropriations Committee asking them to vote against an amendment approved by an appropriations subcommittee that would block the FTC from probing television advertising of food products targeted on children.

"Let the FTC conduct its inquiry; it may help us raise wiser, healthier children," the wives wrote.

"As mothers and as citizens, we appeal to you to recongnize television as a major influence on the nation's young," they said. "If the FTC can help to make this experience more educational, this effort should not be suppressed."

The subcommittee in question is directed at a controversial preceeding undertaken by the FTC this spring to look into problems posed by television advertising directed at children, and to decide whether the agency should do anything about them.

The FTC staff had recommended to the five-member agency that it propose a ban of TV commercials aimed at children "too young to understand the selling purpose" of advertising; a ban on the advertising of highly sugared products to children under the age of 12, and a requirement that advertisers of other sugared products aimed at youngsters contribute to a fund that would balance the ads with separate dental and nutritional messages.

The FTCs proboe of children's advertising is a high stakes issue and has generated lobbying on the Hill by representatives of sugar and food companies and the broadcasting industry, who reportedly hope to head off the FTC.

The appropriations, subcommittee amendment, adopted two weeks ago on a 5 to 4 vote would prohibit the FTC from spending any money - including staff salaries and expenses - on any rulemaking proceeding that could limit television advertising of food that contains ingredients that are generally considered safe for human consumption. That would cover sugar.

But the congressional wives don't like that. "We think the congressmen should be made aware of how important people think the children's advertising food issue is," said Kathy Murphy, the wife of Rep. John M. Murphy (D.N.Y.). She is the mother of three young children (Murphy has three other children by a' previous marriage) and was one of the signers of the letter.

She was one of the four wives destributing the letter door-to-door yesterday. She knows many of the congressmen, and said their reaction to her was generally good - when she was able to talk with them personally. "But that does not tell you what they are going to do," she pointed out. "I am a political realist."

Murphy and about 60 other wives are members of a congressional wives' group that studied children, nutrition and television and presented a report to Congress last year.

In their letter, they noted that a "moderate" television-watching child views about 10,000 food commericals a year, representing about 70 hours yearly of "polished food information." Some of the foods are good and others are inferior, the letter noted, but "almost without exception the food commercials omit any dental and nutritional information.

"The FTC's inquiry can lead to an improvement of children's understanding of food values," they said.

Besides Murphy, other signers of the letter were Landis Neal, the wife of Rep. Stephen L. Neal (D-N.C.); Gayle Kildee, the wife of Rep. Dale E. Kildee (D-Mich.); Suzie Dicks, the wife of Rep. Norman D. Dicks (D-Wash.); Rose Nowak (D-N.Y.); Sala Burton (D-Calif.); Elinor Bedell, the wife of Rep. Berkley W. Bedell (D-Iowa); and Merle Edgar, the wife of Rep. Robert W. Edgar (D-Pa.).

Besides the congressional wives' letter, Appropriations Chairman George H. Mahon (D-Tex.) has received a letter from Commerce Committee Chairman Harley O. Staggers (D. Va.) an six commerce subcommittee chairmen protesting the appropriations amendment, but on generally different grounds. They said the Commerce Committee has ligislative jurisdiction over the FTC, not the Appropriations Committee and notes that the Appropriations paanel's panel's own 1975 report called children's television advertising "a high priority topic."

The Appropriations Committee will try to settle the issue at a meeting scheduled for May 23.