A prosecution witness testified yesterday in U.S. District Court that Glenn I. Wright, one of two men charged with kidnaping the wife of a wealthy businessman here, told her shortly before the July 19 abduction that a "business deal" would soon enable him to repay thousands of dollars in debts.

The witness, Georgiana Gates, 39, of Houston, testified that Wright gave her a $6,000 check as partial repayment of $16,000 in short-term loans. The check, she said, was postdated by Wright to July 26, seven days after the kidnaping.

The kidnaping victim, Edith Rosenkranz, 60, of Mexico City, was abducted at gunpoint from the Sheraton Washington Hotel and held for 48 hours. She was released unharmed after her husband paid a $1 million ransom, which was later recovered by the FBI.

Gates, a friend and bridge partner of Wright, testified that after Wright was charged in the kidnaping, she contacted Wright's bank in Houston "and they told me the check was no good."

Prosecutors depicted Wright yesterday as a financially troubled Houston entrepreneur who concocted the kidnaping plan after learning from a friend of the Rosenkranzes that the couple would be attending a national bridge championship tournament at the Sheraton.

Wright, who has been held at St. Elizabeths mental hospital since his arrest, will contend to the jury that he was insane, Wright's lawyer, William Garber, has said.

Wright, who caused a brief delay in the trial on Monday because he was too sedated to stay awake, appeared alert in court yesterday. He smiled and shook his head at one point during Gates' testimony.

A lawyer for Wright's codefendant, Dennis Moss, 27, of Houston, told the jury in an opening statement that Moss took part in the kidnaping because he was afraid of Wright.

The FBI agent in charge of the investigation, James N. Samples, testified that authorities found a fully loaded .38 revolver in the van driven by Moss when Rosenkranz was released. Agents also recovered a beige briefcase containing the ransom.

Samples testified the briefcase, stuffed with $100 bills in $10,000 packets, weighed 35 pounds.

Edward M. Wold of Houston, a professional bridge player and manager of championship bridge teams sponsored by the Rosenkranzes, testified that Wright asked him last summer whether he planned to attend the Washington tournament. Wold told him that he did.

Wold said he was known in the world of professional bridge as Rosenkranz's bridge partner.

At a dinner party at Wold's home shortly afterward, Wold testified, Wright said he also planned to travel to Washington for the competition. Wold said he was surprised, because Wright's interest in competitive bridge had lapsed in recent years.

Prosecution witnesses today are expected to include Orland D. Tolden, 26, of Houston, who has pleaded guilty in the kidnaping and is awaiting sentencing. According to courtroom statements, he is Wright's former roommate and lover. CAPTION: Picture 1, GLENN I. WRIGHT . . . said to have awaited "deal" cash; Picture 2, EDITH ROSENKRANZ . . . kidnaped for $1 million ransom