When videotapes stolen from a medical research laboratory this summer revealed callous scenes of technicians bashing the helmeted heads of brain-injured baboons, the reaction was strong. Animal rights activists called it murder, scientists called it an unfortunate means to a valuable end, and the federal government called it off.

Health and Human Services Secretary Margaret Heckler suspended funding for the controversial project one month after members of the Animal Liberation Front raided the University of Pennsylvania's Head Injury Research Center and showed portions of the stolen videotapes on Capitol Hill. Praised by animal advocates as "a complete victory" and denounced by scientists for "capitulating to the demands of an irresponsible advocacy group," Heckler's action focused new attention on the longstanding conflict over the use of animals in medical research.

At the heart of this debate is the sensitive ethical issue of what obligations human beings have to protect other species.

Animal rights activists challenge the morality of virtually any use of animals in research, product testing or education.

"Why allow painful experiments on animals and not on human beings?" says Alex Pacheco, a laboratory volunteer turned animal rights advocate who heads the People for the Ethical Treatment of Animals (PETA). "The vast majority of animals used suffer from fear and terror and hunger and pain just like humans do."

Scientists, however, say animal experimentation is necessary to improve the medical care of humans.

"Nobody wants to use animals when there are other alternatives," says Dr. Estelle Ramey, physiology professor at Georgetown University. "But we have to give priority to human life."

An estimated 20 million animals are used for research, according to the National Research Council. The vast majority of animal subjects are rats and mice. Some 138,000 dogs and 50,000 cats, plus monkeys, pigs and frogs, are also used in research.

These animals are drugged, infected with disease, operated on and probed in thousands of experiments that medical researchers argue are central to the quest for new knowledge and improvements in medical care.

"We've witnessed an extraordinary outpouring of new drugs, devices and procedures to relieve human suffering and save lives," University of Maryland medical school chancellor Dr. Edward N. Brandt Jr. told the National Symposium on Scientific Needs and Progress, sponsored by the National Institutes of Health last year. "I would venture to say that very few of these achievements -- maybe even none of them -- would have been possible without the use of vertebrate animals somewhere along the research path."

The middle ground between those who want to ban animal research and those who might frivolously experiment on animals was made clear by Heckler when she suspended funding from the Pennsylvania laboratory on July 18:

"The use of animals in biomedical research is essential in order to develop medical strategies that are critical to the saving of human life and human well-being. I support that principle. However, the use of animals must occur under protected and humane conditions, and only for scientifically necessary purposes."

Although the medical research community and animal welfare advocates have debated the issue for well over 100 years, Heckler's action took on symbolic significance because it was one of the first times a Cabinet official had recognized the plea for stronger government action to protect animals.

Some members of the medical community also have called for stronger action to protect animals. "It is an embarrassment that the medical community has dragged behind the animal rights movement in understanding the moral blind spot inherent in animal research," wrote Dr. Neal D. Barnard, chairman of the Physicians Committee for Responsible Medicine, in a recent letter to the editor of The Washington Post. "It is no less embarrassing when the defense of grants is held dearer than an objective evaluation of those to whom we entrust our medical research appropriations."

Despite their sometimes conflicting goals, those involved in the debate over the use of animals in research generally agree on one thing -- the targets of their respective campaigns. The key targets are the attitudes of public policymakers, newspapers and television, and the general public regarding the proper social balance between scientific needs and animal welfare.

The issue has taken on new intensity in recent years as animal rights activists have adopted confrontational tactics -- such as illegal break-ins in research laboratories -- to publicize what they view as abuse and inappropriate use of animals in the laboratory. The radical animal rights groups are calling for the elimination of the use of animals in research.

Signs of the conflict abound in federal and state legislatures. Congress has a number of bills before it, and some 80 measures relating to the use of animals in research were introduced in state legislatures in the past year. The medical research lobby also has increased its efforts to convince the public that humane animal use is a critical link to scientific progress.

"We are in an era, let's hope a brief one, of exceptionally high-intensity activism seeking to redefine man's relationship to animals," Larry L. Horton, vice president for public affairs at Stanford University, warned medical school officials at a recent meeting. "This is no time to cat-nap in the back of the bus."

The new era of confrontation dates to a 1981 incident at the Institute for Behavioral Research, a private research laboratory in Silver Spring. Police, acting on information provided by a lab volunteer, entered the facility and found monkeys in need of veterinary care. The researcher was accused of subjecting monkeys to cruel treatment, but the charge was ultimately dropped when a court ruled that federal, not state, animal protection laws applied. The lab volunteer, Alex Pacheco, has become a full-time activist as head of PETA.

Since then, dozens of reported incidents, including illegal entries, thefts, vandalism, the "liberation" of animals, demonstrations, bomb scares and personal threats, have been attributed to the Animal Liberation Front -- an organization at the radical fringe of the animal welfare movement -- and other animal advocacy groups.

Most of these incidents began when laboratory employes passed along information to animal welfare activists about the alleged improper use of animals. The incidents have ranged from the theft of a few animals to what the PETA characterizes as "the largest animal raid in history," at the University of California at Riverside last April. Some 470 animals were stolen, anti-research slogans were spray-painted on the walls and computers and other equipment were destroyed.

The most notorious break-in, in terms of galvanizing congressional concern about animal use, was the June 1984 incident at the University of Pennsylvania's Head Injury Clinical Research Center. Members of the Animal Liberation Front -- who anonymously accepted responsibility for the crime -- stole dozens of videotapes, destroyed research records and damaged computers by pouring chemicals on them. The videotapes showed experiments in which baboons' heads were subjected to sudden jerking motions by a specially built machine to cause brain injuries.

It was an excerpt from this stolen tape -- showing young technicians making callous comments, smoking and appearing to cause pain to inadequately anesthetized baboons in unsterile conditions -- that led Heckler to seek an investigation by the National Institutes of Health and ultimately resulted in the suspension of federal funding of the research. While Heckler's action left animal rights advocates ecstatic (and the academic and science communities infuriated), the Reagan administration is hardly of one mind on this issue. The president's annual budget has, for the last four years, proposed eliminating funding for the Agriculture Department's inspections of medical research laboratories that use animals. The administration has suggested that states, industry and humane groups assume those responsibilities. Each time Congress has restored the $4.8 million budget of the animal welfare program.

Individual members of Congress have, in recent years, provided leadership on the issue. Congress first enacted legislation specifically addressing the use of animals in 1966 -- the Laboratory Animal Welfare Act.

More recently, a General Accounting Office study raised questions about the Agriculture Department's performance in monitoring the use of animals. The GAO's May 1985 report, which had been requested by a Senate Appropriations subcommittee, found that many animal welfare inspectors had been inadequately trained and that the inspection service had no "formal system for scheduling inspection visits."

The research and animal welfare communities lobby every year for increased funding to ensure that Agriculture's inspection program is adequately enforced. Senate Majority Leader Robert Dole (R-Kan.) and Rep. George E. Brown Jr. (D-Calif.) have introduced legislation that would strengthen Agriculture's regulation of the use of animals in research. Brown, whose district includes the Riverside laboratory recently broken into, also has introduced legislation making such activity a federal crime.

Now, Congress also is on the threshold of approving legislation that would make HHS take steps to ensure the humane treatment of animals in research funded by its agencies. Rep. Douglas Walgreen (D-Pa.) is the chief architect of this provision, which recently cleared the House as a part of legislation dealing with NIH. A similar measure has also cleared the Senate.

Greater congressional interest in animal use issues has influenced attitudes at HHS regarding animal use, particularly within the ranks of the NIH's leadership. In June, the department published a new "Public Health Service Policy on Humane Care and Use of Laboratory Animals by Awardee Institutions." The policy, similar to -- and in several instances more stringent than -- the requirements called for in the House- and Senate-passed legislation, place particular emphasis on making institutions that operate research laboratories funded by Public Health Service agencies more accountable for the animal-use practices of those laboratories.

Recently NIH director Dr. James B. Wyngaarden has shown greater resolve to make certain that the agency and its grantees provide for the humane care and treatment of research animals. In a closed-door session on Aug. 13 with the directors of NIH's bureaus and research institutes, Wyngaarden questioned whether the "trust relationship," which the agency has long relied on with its grantees, provides adequate protection for animals. The basis of this understanding is an animal welfare assurance statement that grantees submit with their applications.

"Wyngaarden believes we need more than a vague promisory note," said one meeting participant, "to guarantee that grantees are abiding by NIH regulations."

Also discussed at the closed-door meeting, according to two participants who agreed to discuss the session on the condition that they not be identified, was whether NIH should install hotlines so people who suspect laboratories are engaging in practices detrimental to research animals could report such activities to the government.

Wyngaarden ended the meeting by creating several working groups charged with recommending how NIH can develop more effective mechanisms for monitoring research in which animals are employed in highly sensitive situations (such as the Pennsylvania brain injury laboratory), how the agency can monitor more aggressively the animal-use practices of all NIH grantees, and how NIH facilities that may be subject to future break-ins or demonstrations could be made more secure.

Wyngaarden also directed the National Library of Medicine to search the medical literature to make sure researchers who use animals are not duplicating work done elsewhere.

He also plans to create, as he told his lieutenants in a recent internal memorandum, "a decisive, accelerated program" of accreditation of all NIH laboratories by the American Association for Accreditation of Laboratory Animal Care, a multimillion-dollar undertaking.

The decision reflects Wyngaarden's belief that only if all of NIH's own laboratories are above criticism can the agency effectively pursue problems among its grantees.