BOOK REVIEW / NOVEL : Campy, Post-Realist Romp--With a Dose of Murder : RENT BOY <i> by Gary Indiana</i> ; Serpent’s Tail, $10.99, paperback; 115 pages

OK, so the 500 channels of the “information superhighway” will target increasingly tiny mini-audiences. Fiction seems to be headed that way too, although it isn’t all the authors’ fault; the reading public has been splintering on its own, and books can only follow.

Case in point: “Rent Boy,” Gary Indiana’s novel about gay hustlers in New York City who get involved in a crooked doctor’s plan to murder people and sell their body parts to hospitals for transplants.

This is a funny book with a high degree of linguistic sophistication. It also contains all the four-letter words, plus graphic descriptions of sex, kinky perversions, drug abuse and mayhem.

A quick imaginary survey of American readers shows that 40% would condemn Indiana and his works, unread, to perdition. Another 27%--the same kind of folks who gave us the “don’t ask, don’t tell” policy on gays in the military--would leave “Rent Boy” alone, so long as they didn’t have to read it themselves.

Of the remainder, 8.6% would read the book, discover a whole new world and be moved to sympathy. These would be more than offset by the 11.1% who would read the book, discover a whole new world and think that Indiana’s description of it only confirmed their prejudices.

That leaves the 13.3% for whom Indiana is actually writing. They are readers for whom this isn’t a new world at all--Jean Genet and John Rechy opened up the territory a generation ago, and Indiana’s narrator, Danny, reads the stories of Dennis Cooper.

They are readers who not only won’t be shocked by the realism of this novel but will recognize it for the campy, post-realist romp it partly is.

Partly, because Indiana (“Horse Crazy,” “Scar Tissue & Other Stories”) seems to want it both ways. Danny, the “rent boy” of the title, is in search of love and meaning as he studies architecture, waits tables in a restaurant catering to trendy writers, and sells himself to businessmen. He’s a distant, debauched cousin of Holden Caulfield--a youthful truth-teller who sees himself surrounded by phonies.

“I think I’ve overheard a million john life stories and another million whore life stories and . . . the john’s story is always ‘I’m lonely,’ and the whore’s story is always ‘I come from a dysfunctional family,’ ” Danny says cynically--although he is from a dysfunctional family and is as lonely as any of his customers.

Yet Indiana’s control is less certain than J. D. Salinger’s was in “The Catcher in the Rye.” Danny is supposed to be telling the story in letters to an ex-lover, but that relationship never comes into focus. His quieter tones of voice keep getting drowned out by derisive glee. He piles on details of dress and decor and slang simply because it’s too much fun to stop; he turns the other characters into cartoon figures, especially the doctor, Crashnitz, and his nurse, Mavis:

”. . . back to the ratty blond hair and so forth, but with some brand-new touches, for example a dozen clanking bracelets on each arm, and a green Mylar dress that made her breasts look strange, fishnet black stockings and red heels and a makeup job which, given her square chin and all, gave the very faint impression of like an incipient beard. . . .”

It comes as a bit of a surprise to find that Indiana can use the same stylistic extravagance to deeper purpose, as when Danny contemplates the murder plot:

“I can tell you what the cocktail lounge at the Ramada’s like, think of dark Formica and grainy indirect lighting and emotions collecting in front of you in the little puddles formed by your cocktail glass, islands and continents of feelings you don’t know how to place anymore, and voices, the so-called human element, that remind you you’re chained to the earth by a million little details: . . . They might as well be called Mavis or Stanley or Chip, or the boy who ran away from home to learn fear . . . or just a client whose loneliness and despair jut out on his face in the seconds before he comes. . . . So, maybe I found my will in the Ramada Inn, who knows.”