Coulombe was recalled from Triple-A Nashville on Sunday.
Coulombe will serve as the temporary replacement for starter Sonny Gray, who was placed on the DL Sunday due to a strained right trapezius muscle. The lefty reliever saw two innings earlier in the year, but was later sent back to Triple-A, where he owns a 0.56 ERA over 16 frames. Coulombe will provide bullpen depth in the short term, but his roster spot may be at risk once the A's decide on Gray's replacement in the rotation.