These mouse restrainers are built in cylindershaped perspex. Lateral slots and holes allow for the animals ventilation and makes the access for interperitaneal (i.p.) drug administration possible. The available space for the animal can be adjusted by means of a sliding piston, thereby keeping the whole tail free for the pulse transducer and the cuff positioning or for intravenous (i.v.) drug administration. The animal is led in from the back and can walk out in the front, thus avoiding dragging it backwards.