"Bonnie, how would you like to have a heart attack?" The writers asked. "I'd love to, she replied. And so on Sunday night, at 8:30 on Channel 9, Bonnie Franklin as Ann Romano will suffer cardiac arrest as the hit CBS series "One Day at a Time" gets into deeper water than usual.

The writers and producers met with the cast at the beginning of the season to map out this year's adventures and calamities for the divorced mom and two teen-age daughters who allegedly live in Indianapolis but who actually inhabit a sound stage off Sunset Boulevard.

They've been through a lot already, in four years on the air -- menopause, teen-age runaways, epilepsy and mental retardation and other things the Ricardos and Mertzes and Ozzie and Harriet never dreamed existed, but all perfectly normal for a Norman Lear show.

If there is one true television hero of the '70's its Uncle Norman. Lear made situation comedy for real life. With "All in the Family" and many other programs, he broadened the scope, altered the form, shattered precedents and continually challenged the audience. Though no longer active overlord for "One Day at a Time", Lear is the one who developed the show and whose T.A.T. Communications produces it.

When Ann has her heart attack Sunday night, it will be the heaviest crisis yet faced by the show's characters. But in the Lear tradition, a dramatic jolt will often be followed by, though not erased by, a gag line one moment later.

So although the first act of the Bob Baublitz script ends with a poignant fade-out on poor Annie, lying in a hospital bed and with tubes connecting her to various bottles and machines, the second act opens with a joke about the same sight: "She looked like the Bionic Woman getting a tune-up.

Does this soften the impact of the shows, or wink to the audience that it's all only make-believe? Not really. It simply makes a worthwhile program that much more palatable and attractive to many more viewers. Consistently in the top 20 Nielsen shows last season. "One Day" has been consistently in the top 10 this season.

The reasons for its success are evident in "The Heart Attack": The characters seem authentic and representative of the time in which they live. One can't help feeling for them, the problems they face, and their determination to get by. And the key roles have been cast with what has become a hallmark of Lear shows: a touch of genius.

Bonnie Franklin as Ann goes through one crisis at a time with bounce and resolve, and her badinage with MacKenzie Phillips and Valerie Bertinelli as the daughters is believably flip most of the time, convincingly heartfelt at others. Pat Harrington's custodian Dwayne Schneider is an amusingly sleazified update of the Ed Norton character in "The Honeymooners."

Together this little band jumps or crawls over the hurdles of changing attitudes and more. Unlike Mary Richards, as played by Mary Tyler Moore, Ann Romano is allowed a sex life, even has affairs that are discussed by her daughters, and all three wrestle perpetually with the complications that go with human sexuality. Almost always the show stays above the tease-and-titter hijinks of lowbrow farces like "Three's Company."

The fact that Ann has a heart attack at all is a sign of the times. Gains made by women in employment and management bring with them the same pressures men have faced. So of course the audience hoots as well as laughs when Harrington blurts out, "Women don't get heart attacks they give 'em."

The premise for the series is disarmingly simple, and yet it didn't become a formula until the Lear people tried to clone it as "Hello, Larry," a sitcom about a divorced man and two teen-age daughters. One of the original, and discarded, titles for "One Day" was "Hello, Ann."

"Larry," which NBC keeps trying to bolster with guest appearances by Gary "Diff'rent Strokes" Coleman, lacks completely the credibility and sympatico that make "One Day" work. "Larry" will be lucky to make it through the season, which is more than the show's hapless star, McLean Stevenson, deserves.

Whether or not the nation is beset with "malaise," as President Carter claimed a few months ago, there is certainly a Hollywood malaise in TV production right now. Mork has lost his na-no na-no. The casts of "Happy Days" and "Laverne and Shirley" stalk through the roles on wings of ether. It's therefore all the more impressive that "One Day at a Time" hangs in there with renewed vitality. This comedy on the theme of resiliency is resiliency itself.