Three Senate health leaders -- Democrat Edward M. Kennedy and Republicans Jacob Javits and Richard S. Schweiker -- served notice yesterday that they would reshape and probably increase the Carter administration's fiscal 1980 health budget.

At the first hearing in this Congress on administration health plans, the three confronted Health, Education and Welfare Secretary Joseph A. Calident Carter's austere health budget would cut vital programs.

Califano defended the tight $7.8 billion Public Health Service budget -- the government's main funding for health research and training and a wide array of health services -- as "prudent" but "compassionate" and a stark necessity to lick inflation.

But Kennedy and Schewiker called the spending plans inadequate, and Javits said that at the least the Senate -- while as "lean" and "economical" as the president -- is likely to have "other priorities."

The administration is asking for $7.8 billion to fund 1980 health programs. This is $53 million less than Congress voted for the current year and $472 million less than it would take to keep all the programs at their present level.

The "intolerable" result Kennedy said, would be to "undermine the American health care system," "jeopardize" the quality of medical schools, "seriously damage" health and research programs, and not "reflect the value that the American people assign to their health."

The confrontation took place before the Senate Human Resources health subcommittee headed by Kennedy of Massachusetts. New Yorkes Javits stepped down this session as the Human Relations Committee's ranking minority member to assume the comparable seat on Foreign Relations, and Pennsyvanian Schweiker was just elected to replace him.

For Kennedy, the day's debate represented another of his repeated attacks on administration policies. And Schweiker agreed with him fully, calling the session the first where "I haven't had to figure out which of us is in the opposition."

In particular, the senators flayed plans to slash support for medical and nursing schools and students, and to restrict funds for medical research.

Backed by testimony from three major health groups -- the Association of American Medical Colleges, the American Nurses Association and the Coalition for Health Funding, representing 54 organizations -- Kennedy said the administration program would fail to produce needed primary-care doctors and nurses.

He and his subcommittee colleagues -- and Dr. John A.D. Cooper, president of the medical college group -- said medical schools would be forced to raise already steep tuitions by a quarter to a third, in effect closing their doors to almost all but the rich.

Forcing students to borrow thousands of dollars a year to finish their medical educations, said the senators, would produce doctors eager to enter the high-paying specialties that are already too well populated, instead of lesser-paying primary care where doctors are needed.

As to nurses, Califano said that present programs will produce enough, just as they will produce enough doctors. But Kennedy said that "in city after city" nurses are in "desperately short supply."

Califano said that, even with some cuts and restaints, there will be increases for many important programs. He described boosts for mental health, disease prevention, anti-alcoholism and anti-smoking efforts and child and adolescent health.

But above all, he said that the fiscal 1980 health budget "must be seen from a national, not just a health perspective... Both you and I can identfy serious unmet health needs that require additional federal dollars," he acknowledged, "but we have had to make some difficult decisions."