BOB FLEMING woke up one morning with his pulse pounding out of control. He mentioned nothing to his wife, but stopped at the nurse's station on his wayto his job as a congressional administrative assistant.

After measuring his blood pressure at 245 over 90 and his pulse at 160, one nurse called the hospital, one called the fire departemnt, another called George Washington University Hospital where he was observed and released. His doctor told him he must be in fairly good condition to experience such an incident with no damage to the heart.

Three "incidents" later, the heart appeared damaged and Fleming began a restricted diet. To avoid trips to the hospital, he says, he must watch what he eats.

One of the things he watches is his sodium consumption. At least he tries to watch it, but sometimes it's hard to see things that are invisible. The government requires no special labeling for sodium in processed foods, so maintaining a restricted-sodium diet isn't as easy as avoiding pretzels and pickles.

Rep. Albert Gore (D-Tenn) says that the "levels of sodium added to processed foods are incredible." He is co-sponsor of a bill that, if passed, will require sodium labeling on all processed foods.

Public concern over sodium content in foods is growing, he says. High blood pressure (hypertension) affects about 60 million Americans, predisposing them to heart disease, stroke and kidney disease.

"The research is now conclusive," he says. "There is no argument whatever that high levels of sodium contribute to high blood pressure." Many scientists believe that excessive sodium causes high blood pressure; many others believe that those with high blood pressure can improve their condition by cutting down on sodium, which means cutting down on salt, monosodium glutamate, sodium nitrate and much, much more.

The issue of sodium labeling has swelled some controversy. Food processors aren't particularly receptive to the idea,because reduced sodium correlates significantly with reduced sales. Consumer advocates want it on all foods -- and as soon as possible -- so that people can identify high-sodium products, and compare foods. Gore has proposed legislation to require mandatory labeling.

But the Food and Drug Administration has surfaced above the sodium brouhaha and now strongly recommends that industry get busy with voluntary labeling. The labeling question appears to be the quintessential test to see if Reagan's approach of voluntarism will work in the food world. Consumer advocates wait with bated breath to see if unregulated industry can change itself to benefit consumers.

Arthur Hull Hayes, commissioner of the FDA and former chief of the hypertension unit at Hershey Medical Center in Hershey, Pa., has said as much. To a meeting of the National Food Processors Association he cautioned, "A great many people, in the Congress, in the consumer community and in other industries, are watching this effort. They want to see whether voluntarism still can work. . . . For some, this sodium program has become a test, to see whether industries like yours will work without mandatory regulation to address a serious public health problem. The stakes are high, not only from a health standpoint, but also from a regulatory standpoint."

The FDA introduced a five-point plan last April that encourages industry to reduce the amount of sodium in processed food, calls for more consumer education about the merits of a sodium-reduced diet, proposed regulations that would make sodium labeling part of the nutrition label now included on 40 percent of processed foods, proposes monitoring sodium consumption in the population and considers some form of legislation concerning sodium labeling. In September, Hayes said he would wait a year before reviewing the status of sodium labeling and education.

The FDA is pleased with the progress so far. Companies such as General Foods, Quaker Oats and Campbell's Soup have agreed to list sodium content on their labels. One spokesman for the FDA says that companies will work faster voluntarily than they will if mandatory regulations are passed.

Michael Jacobson doesn't agree. As director for Center for Science in the Public Interest, he is anxious to get mandatory regulations passed requiring all foods, including salt, to have sodium labeling. He's skeptical that the FDA, which has no quantitative goals to measure progress, will find any fault with industry actions by autumn. He believes that the voluntary approach to labeling could cause a delay of many years. He maintains that industry is acting now only because the threat of pending legislation -- support for Rep. Gore's sodium-labeling bill -- hangs near.

Jacobson counters the claim that consumer education is increasing. The government has withdrawn funds for the Nutrition Education and Training project, now charges money for the pamphlet on the dietary guidelines and will not publish the sequel to "Food," which would have encouraged lower salt consumption.

Wayne Pines, spokesman for the FDA, says it will continue public service announcements -- one of which includes Redskins Halfback Terry Metcalf -- about lower sodium consumption. He maintains that the FDA effort will, in fact, continue on all fronts. "A lot more yet needs to be done," he says.

The best of all possible worlds, he says, would be one where it would be easier for people to maintain a low sodium diet through increased labeling, greater availability of low-sodium food and more education and awareness.

Jacobson and Gore have similar goals. Their means to the end, however, differ. They don't believe that industry will act quickly or adequately without mandatory regulations. Hayes disagrees. It's a test of the new economics.