Collmenter was forced into action in the second inning when Trevor Cahill left after being hit in the right hip with a line drive.
"We used Collmenter the other day, so he's not available today," D-backs manager Kirk Gibson said before Friday's game. "We were uncomfortable with that, so we got Spruill up here."
Spruill started the year in Double-A Mobile but was quickly promoted to Reno, where he is 3-3 with a 4.06 ERA in nine starts.
In his last two starts for Reno, he tossed 17 scoreless innings.
"He's throwing the ball great," Gibson said. "Kind of keeps the ball down, good sinker, he's got a split, a little slider."
To make room on the 25-man roster, the D-backs designated infielder Josh Wilson for assignment.
With Collmenter likely able to pitch again in a couple of days, it seems Spruill's stay will be a short one, and the team could activate second baseman Aaron Hill on Sunday or Tuesday to take Spruill's place.
Spruill, the D-backs' No. 8 prospect according to MLB.com, got the nod over top prospect Tyler Skaggs, largely because of the role he would be filling.
"I think we see Spruill better out of the bullpen, and there was less comfort with Skaggs coming out of the bullpen," Gibson said.
Spruill was acquired in January as part of the deal that sent Justin Upton to Atlanta.