Reciprocating-piston internal combustion engine with intake and exhaust valves actuatable by sliding cams of a camshaft, arranged so that they are rotationally locked but axially moveable on a base shaft, and with an actuator unit for each sliding cam unit with at least one actuator pin for the displacement of the sliding cam units into different axial positions. The actuator pins are spring-loaded in the direction of the sliding cam unit and are fixable in their retracted position away from the sliding cam unit by latches having spring-loaded control needles that correspond to clamping bodies of the latches and are releasable via an electromagnet and permanent magnets that are in active connection with the control needles, and acceleration of the control needles defined by the spring force of each moving mass due to their springs is compensated by the acceleration of the actuator pins due to their allocated compressive springs.