Argentian sent two big guns into the Kennedy Center Concert Hall last night for the first orchestral program of the present Inter-American Music Festiva: conductor Giullermo Scarabino and bandoneonist-composer Astor Piazzolla.

In the concerto for bandoneon, strings and percussion, they scored the big pop hit of the evening. The bandoneon looks and sounds much like an accordion though there are differences. Piazzolla, who is called the "Numero Uno" performer on the popular Argentine instrument, uses a body english in playing that is more involved than anything in memory.

His concerto is predictable high-class kitsch, full of chromatic runs and melting strings. There are also expressive moments, some of which recall Paul Desmond Brubeck's "Dialogues." The festival orchestra, which played very well for Scarabino throughout a demanding evening, provided lush backup for the soloist who received a standing ovation.

The evening opened with four brief preludes by Alfonso Letelier of Chile that sounded rather like not bad rewrites of Schoenberg's "Five Pieces." Heitor Ville-Lobos' suite, "Discovery of Brazil," was written for a 1936 film. It is indeed gorgeous movie music.

The program closed with a revealing account of the Second Symphony by Lester Trimble of this country. Though it was commissioned by the Koussevitzky Foundation in the Library of Congress and is now 14 years old, this was the Washington premiere for the asstringent but skillfully constructed work.