Lawyers for former Washington abortionist Dr. Robert J. Sherman charged yesterday in D.C. Superior Court that the medical director of a Northern Virginia abortion clinic was "threatened with economic" reprisals if he went forward with plans to testify for the defense at Sherman's second degree murder and perjury trial.

Defense attorney Robert F. Muse, contending that the reprisal statements grew out of an effort by the government to harass and intimidate defense witnesses, asked Judge Fred B. Ugast to dismiss the charges against Sherman or declare a mistrial because of "prosecutorial misconduct."

Principal Assistant U.S. Attorney Carl S. Rauh strongly denied the misconduct charges. He told the court that Muse had "mischaracterized" testimony concerning the medical director heard by Ugast yesterday during an unusual, four-hour, closed-door session in his chambers.

The request from Muse climaxed three days of complaints from defense lawyers that the government has tried to intimidate defense witnesses and discourage them from testifying in Sherman's behalf, all of which the government has repeatedly denied.

The bitter dispute peaked Tuesday when Dr. Thomas H. Gresinger, medical director of the Northern Virginia Women's Medical Center, informed Muse and his cocounsel, Constance O'Bryant, that a coworker and another doctor had inquired about his plans to testify at the Sherman trial, now in its fourth week.

When the defense opened its case Monday, Muse told Ugast that defense witnesses had received persistent, late night telephone calls from Rauh and that witnesses had been telephoned by D.C. police homicide detectives, acting as investigators for the U.S. attorney's office. After contact with the government, Muse contended, some defense witnesses withdrew their cooperation.

Yesterday, Muse told Ugast that telephone calls to Gresinger's coworker and another doctor by Assistant U.S. Attorney Whitney Adams precipitated statements by the doctor to Gresinger that Gresinger's testimony could result in what Muse said were "economic and what we perceived to be professional reprisals."

Muse said that his recollection of testimony was that the doctor, Paul J. Hergenroeder, had told Gresinger that if he testified at the Sherman trial his clinic would run the risk of losing substantial referrals" from groups with which Hergenroeder was associated.

Rauh, however, told Ugast, that his "distinct recollection" of the testimony in chambers yesterday was that the doctor had "not suggested economic reprisals" but had had instead a "low-kay" conversation with Gresinger about procedures at the Norther Virginia abortion clinic.

Both the coworker, Sharon McCann, who is the administrator of that clinic, and the doctor, Paul J. Hergenroeder, were called to Ugast's chambers yesterday to testify about conversations late Monday with each other and with Adams and Gresinger.

Hergenroeder practices obstetrics and gynecology in Northern Virginia. In March 1975 Hergenroeder, then a resident at D.C. General Hospital, attended a medical procedure performed there on 16-year-old Rita McDowell. McDowell died in the hospital's intensive care unit four days after she visited Sherman's clinic in Northwest Washington for an abortion on March 4, 1975. At one times the government had planned to call Hergenroeder as a witness in its criminal case against Sherman.

Reached for comment yesterday, Hergenroeder at first said he would talk with a reporter later in the day about the case. Later, however, he was unable to talk because one of his patients were going into labor.