TOKYO (AP) _ In a major breakthrough for transplant advocates, Parliament's lower house approved a bill today to legalize heart transplants not currently performed in Japan.

Passage of the bill _ it still must clear the upper house _ came a week after the death of an 8-year-old Japanese girl who was forced to fly to Los Angeles to await a heart transplant that never came. Her plight aroused a flood of sympathy across the nation.

``A philosophical discussion can go on endlessly. But then there is no progress in the real situation,'' former Prime Minister Toshiki Kaifu said after voting for the bill, which passed the 500-member lower house 320-148.

The issue of organ transplants is a highly volatile one in Japan, fanned by widespread taboos about cutting into corpses and fears that doctors will focus more on getting fresh organs than on saving the lives of potential donors. Even if the bill passes, doubts remain on whether enough Japanese will contribute their organs.

The bill requires a written statement of intent from the donor as well as consent from the donor's family. Children under 6 are not eligible to be donors, which will sharply reduce the number of possible lifesaving operations.

Today, as lawmakers were debating the bill, 20 protesters _ some in wheelchairs _ chanted outside the Parliament building.

``It will lead to a discriminatory view that some lives are better than others,'' said Yoshiko Aoki, one of the demonstrators. ``It could spread to the idea that the handicapped, the elderly don't deserve to live.''

Transplants are not banned in Japan, but current laws define death as when a patient's heart stops beating. At that point, organs rapidly deteriorate, making them unsuitable for transplant.

Most transplants in the United States use organs from brain-dead donors, whose heart and other organs can continue functioning with the aid of machines until a recipient is chosen.

Transplants in Japan have been limited mostly to corneas and kidneys, and to a lesser degree liver sections, which are not as prone to rapid deterioration or can be taken from living donors.

In Japan, only one of every 20 people on the waiting list for kidney transplants finds a donor, including living donors. In the United States, the figure is one in three.

A vote in the upper house has yet to be set, but approval by the lower house, where the issue has been under debate for years, is a major accomplishment. A similar law was defeated there last year.

Transplant doctors have long pressed for revising laws to allow heart and other transplants from brain-dead donors, but the issue is so controversial that the only party unified on the issue is the Communist Party, which opposes the bill.

The only heart transplant ever carried out in Japan, in 1968, was widely criticized as ethically dubious.

Kouichi Yoshida, a lawmaker who voted for the bill, said he was willing to give his organs for transplant.

``This is something that can't be forced on people,'' he said. ``Now, despite all the medical progress, people have to go to the United States for transplants.''