RICHMOND, JAN. 22 -- A Senate committee rejected today by a vote of 8 to 7 a bill to change Virginia's method of execution from electrocution to lethal injection and sent the proposal to a new subcommittee for study.

The bill, sponsored by Sen. John H. Chichester (R-Fredericksburg) and a majority of the Virginia Senate, opened up some of the old debate for and against the death penalty itself.

Sen. Thomas J. Michie Jr. (D-Charlottesville) was an original cosponsor of the measure but voted against it today in the Senate Rehabilitation and Social Services Committee, changing the outcome of the vote. He said at first he had thought using the injection method would be more humane for both the prisoner and the family but that after listening to arguments this morning he decided it would be "dehumanizing . . . more like putting down your pet."

Saying that he had voted for the original bills reimposing the death penalty in certain cases but has opposed measures to expand it, Michie added that "maybe it's better for it to be grisly and shocking."

This is an argument used both by some death penalty opponents, who believe the public will become disgusted and demand repeal, and by some death penalty proponents, who say a harsher punishment will be a greater deterrent to crime.

Sen. Joseph V. Gartlan Jr. (D-Fairfax) said he opposed the bill to use the injection method both because of his "fundamental opposition and hostility to the death penalty" and because such a change needed more public airing.

Chichester, who supports the death penalty, called lethal injections "a more modern method" of execution that doctors say does not disfigure the body as much as electrocution. "I would like to see us move silently into a more modern era without a lot of sideshows," he said in an interview after the vote.

Sen. Richard L. Saslaw (D-Fairfax), who has supported the death penalty, endorsed the bill and asked Gartlan if he would find it acceptable if the condemned had the choice of electrocution or injection. "I'd like a third choice -- to have a guillotine erected on Capitol Square," Gartlan retorted.

Virginia has 37 persons on death row and has executed six persons since the state revamped its death penalty statute in 1977 to bring it into line with a U.S. Supreme Court ruling that set new guidelines for capital punishment, a state corrections official said.

The committee chairman, Sen. Dudley J. Emick Jr. (D-Botetourt), a supporter of the death penalty, opposed the bill and appointed two other opponents and one proponent of the injection measure to the subcommittee to study it.