Loudoun County supervisors yesterday turned down a request by health care giant HCA Inc. to build a hospital north of Dulles International Airport, bringing to a head years of often caustic debate over development, political influence and the future of medicine in one of the country's fastest-growing counties.

The debate pitted backers of a local Loudoun hospital, founded in 1912 and recently merged with a nonprofit chain of Northern Virginia hospitals, against supporters of Nashville-based HCA, which has about 190 hospitals and $23.5 billion in revenue.

Last night's vote blocking HCA's bid to build a hospital in the Broadlands community, about five miles from Inova Loudoun Hospital, comes after three years of feverish preparation and noisy public debate. The question of where a new hospital belongs turned into a political and legal feud, with both sides leveling accusations of inappropriate political interference.

Both sides paid for a barrage of advertisements and direct mail and mustered supporters to either decry or welcome the Broadlands hospital in numerous hearings. Opponents have emphasized the possible impact of the hospital on newly built communities, citing congestion and noise from a 24-hour-a-day facility. Supporters have said the booming county's single existing hospital is insufficient.

The debate has been vehement, with competing color-coded crowds applauding points at public sessions. At yesterday's session, for instance, opponents wore bright yellow T-shirts emblazoned with the large black symbol for radiation and the words "Impact Zone Resident." HCA, meanwhile, hired a firm to telephone its supporters and forward the calls to supervisors' offices.

Bryan Dearing, chief executive of the proposed Broadlands Regional Medical Center, said after the 6 to 3 vote that HCA may sue. A stenographer hired by HCA sat quietly yesterday beside the dais, as she or others have at meetings for months, typing a transcript of the proceedings.

"We're just very disappointed that a small group of individuals who had a lot to gain . . . seemed to be able to influence the process," Dearing said, noting that Inova Loudoun employees helped fight the HCA proposal. "They didn't want competition. . . . HCA has never experienced this kind of situation."

Woodrow W. Turner Jr., general counsel for the Loudoun hospital, declined to respond in detail to the developments, but said: "We're certainly pleased with the outcome. It's been a three-year effort."

Planning Commission Chairman Lawrence Beerman II, a member of the board of directors at Inova Loudoun, would not comment. He had recused himself from considering the application.

Supervisor Stephen J. Snow (R-Dulles) said the Broadlands proposal would have brought traffic, noise, light and glare. "I don't think the project is compatible" with the residential community, Snow said. "There is a real question about the safety and welfare of the citizens" if the area had been turned into a "thoroughfare" leading to a hospital, he said.

Loudoun Board of Supervisors Chairman Scott K. York (I-At Large), an HCA supporter, said it was "ridiculous" to argue that a hospital would be dangerous. He said HCA had fallen prey to a "good old boy" network in Loudoun. "They are trying to keep a monopoly for themselves," York said of Inova Loudoun and its supporters.

In March, Loudoun supervisors enacted new health policies that undermined HCA's effort. A similar idea was first proposed by executives from the existing Loudoun hospital. The policies passed in March called for a new hospital generally south of Dulles Airport. That area has fewer residents than the area near HCA's Broadlands site but is being pushed by developers, home builders and some supervisors as a vast new hub of residential development.

HCA would have had "a devastating financial and economic impact," Tony Raker, director of community relations for Inova Loudoun, said. "If they can't build there, then obviously there is an economic aspect to it that's related particularly to us."

Supervisor James Burton (I-Blue Ridge) voted with York against denying HCA's application. He did so after berating HCA for what he said was its "reprehensible" bid to move facilities from Arlington to the lucrative Loudoun market and for acting in what he believes is a "predatory" fashion toward Inova Loudoun Hospital. Still, Burton said, he found no basis in county rules to turn down HCA.

Dearing said HCA would keep open some elements of the Northern Virginia Community Hospital in Arlington, in part as a condition of the state's approval of the new hospital, and was not seeking to put Loudoun's existing hospital out of business.