DUBLIN -- A shudder of nervous disbelief went through the capital of the Emerald Isle on Friday afternoon when word arrived in the halls of governance that a big, fat zero had turned up next to the word Ireland in the Reagan administration's foreign aid request.

Not only was the column blank, but Deputy Secretary of State John Whitehead had remarked, in a reportedly offhand way, that the United States "does not receive a real return" on its investment in Ireland, which in any case "ranks down the list" for U.S. assistance in the face of "other needs that appear to us to be more urgent."

There might be an "emotional appeal," or even a "political appeal" for aid to Ireland, Whitehead concluded, but in terms of value for money, Ireland simply didn't rate.

The shattering news was the talk of Irish officialdom. Did not the Americans dye their beer green and parade through the streets in even bigger numbers than the home folks on St. Patrick's Day? Hadn't every American worth his salt at least one sainted Irishman somewhere in his lineage? Didn't they all see, and love, "Ryan's Daughter?"

Within hours of Whitehead's disturbing comments, however, the congressional Friends of Ireland came galloping to the rescue. Friends Chairman Rep. Brian Donnelly (D-Mass.) said he was outraged, according to the Irish Times. Sen. Edward Kennedy (D-Mass.) said he was confident that the United States would cough up the money, "and I expect it to be supported by President Reagan," himself no slouch when it comes to claiming an ancestral touch of the leprechaun. Rep. Joseph P. Kennedy II (D-Mass.), new to the House but certainly not to the issue, warned ominously that "the people of Ireland have many friends in the U.S. Congress."

There are 40 million Americans of Irish ancestry -- 10 times the number of Irish in Ireland -- whose combined political pull has brought together such unlikely comrades as the Kennedys and Sen. Orrin Hatch (R-Utah) in defense of Dublin over the years. The Irish say they aren't sure why Hatch likes them, but they're glad he does.

It must be noted that the hoped-for aid, $35 million, isn't really even for Ireland per se. Rather, it is the third and final slice of a $120 million U.S. commitment to the International Fund, established to bolster the two-year-old Anglo-Irish agreement designed to bring peace to Northern Ireland. By providing seed money to open new businesses and train worthy youths in the high-unemployment north and the Irish Republic border counties, the fund aims to "promote economic and social advance and to encourage contact, dialogue and reconciliation between nationalists and unionists throughout Ireland."

So far, according to its most recent report, the fund has spent all but about 10 percent of the more than $90 million it has taken in, but Irish officials say that the Americans feel the project has not produced enough results. True enough, relations between the two communities in Northern Ireland are still largely restricted to shooting at each other.

But more than just the money -- and even if they end up getting it anyway, as is likely once the Friends of Ireland get to work -- the Irish are always distraught when they feel the Americans have lost interest in them.

More than any of the myriad countries around the world from which we draw our heritage, the Irish have remained steadfast in their admiration and affection for Americans. They fear U.S. trade protectionism, they would like more green cards, they'd rather be neutral than in NATO, and they think our policy in Central America is less than enlightened. But anti-American is a phrase that simply doesn't come up here.

There is, of course, a political dimension to Ireland's love. The protective wing of the United States and its Irish community to the West is seen as a bulwark against the former colonial master we share to the east: Britain, whose monarchical shadow still looms large over this tiny republic.

Dublin reasons that while the Americans may have an intellectual fondness for Maggie Thatcher, and a tight strategic relationship with London, their hearts belong to Ireland.

The Irish count on the United States to intervene when the British begin to bully them over matters such as the Anglo-Irish accord. The Dublin government already knows that Britain's minister for Northern Ireland, John Stanley, is to travel to Washington this spring, hoping to persuade the U.S. government to turn American investors away from the "MacBride Principles," which are designed to promote affirmative action for Catholics in the north and boycott companies that discriminate in favor of the majority Protestants.

That's why talk of nonreturn on investments and low rankings was so troubling here. Fortunately for Dublin, it seemed also to trouble the Reagan administration. By Friday night, the State Department had clarified Whitehead's remarks in a release that seemed to imply that Whitehead simply didn't know what he was talking about -- and that the absence of a dollar sign in the Ireland aid column was merely a technicality to be straightened out as soon as Congress started the welcome process of taking the budget apart.

The United States "strongly supports the International Fund and the Anglo-Irish accords," according to the Irish Times' satisfied front-page rendering of the State Department statement. While it was true that the administration had not requested money for the fund in its 1989 budget, the statement said, "of course, we will ultimately be guided by what Congress authorizes and appropriates and what is signed into law by the president."