Republican presidential candidates took each other on today in a costly exhibition match that produced a frenzy of activity, some bitterness, an orgy of campaign spending and little sense among the contending camps of having accomplished much.

The Pinellas County Republican Caucus was the first real contest between the 1980 contenders. And it did cough up winners, Ronald Reagan and John Connally, in that order, and losers, George Bush, Howard H. Baker Jr. Phillip M. Crane, Bob Dole and Larry Pressler.

But the winners didn't seem to feel very victorious, and the losers certainly didn't appear vanguished after it was all over this afternoon. The private consensus among campaign operatives was that it was for the most part a colossal waste of money, hundreds of thousands of dollars for some of them.

The caucus is one of about three dozen county meetings being held throughout Florida to select delegates by lot to a Nov. 17 presidential preference convention, where a straw vote will be taken. That vote will have no bearing on the state's representation at the 1980 Republican National Convention. Those delegates will be selected in Florida's March 11 primary.

But Pinellas County, with 170,000 registered Republicans, has the largest GOP registration of any county in Florida and perhaps in the entire South. So the selection of its 143 open delegate slots was considered important for most of the candidates, even though the names were chosen not by a vote but out of a barrel.

The caucus today and the convention in November are of special concern to Reagan and Connally, who do not want to be embarrassed in the national media by a poor showing in a state where they must perform well.

Both are showing their concern with heavy advertising and direct mail campaigns here, and the others with telephone banks and transportation pools to the caucuses.

The concern was also evident today as two buses chartered by the Conally campaign pulled up at the caucus site, loaded with aging Republicans rounded up at senior citizen's homes to place their names in the barrel. Even candidates' sons, John Connally III, Mark Connally and Neil Bush, competed for favor among the 800 Republicans who crammed into the small meeting room.

Connally operatives in particular treated it like the real thing, rounding up their delegates as their names were called with a walkie-talkie network reminiscent of national political convention floor fights.

Campaign officials on all sides scurried about among the reporters, assuring them of their "low expectations" for the day and wondering how the results were going to be interpreted in the next day's news.

The precise results were nearly impossible to discern. Some of those selected as delegates chose not to comment, and others simply dodged reporters, slipping out a rear exit for home after paying the required $20 registration fee.

The best counts show that Reagan is supported by between 29 and 36 of the 140 chosen today. Connally was listed as the favorite by between 24 and 33 of the Republicans. Bush followed with about 12, Baker with six, Crane with three and others, including Alexander M. Haig and Pressler, received one vote. Approximately 45 of those selected said they were uncommitted.

If there was any real loser, it had to be Crane, whose supporters thought up the idea of the Florida caucuses as a way of promoting their man in advance of more serious primary races.

The Connally campaign was thought by some observers here to have done better than expected today. But the return on Connally's heavy investment was small in the eyes of some of his supporters.

Though Connally turned out more than 300 Republicans, about a third of those present, for the drawing with his buses and advertising, he won only about a fifth of the county's slots.

Bush experienced the same phenomena, bringing out about 125 but getting only 12 votes. Reagan has dominated the other smaller caucuses held so far in preparation for the November convention in Orlando.

Most campaign officials present today said they hoped that this would be the first and last time Florida or any other state conducted this sort of caucus.