Sublethal plasma membrane disruption (PMD) is an established mechanism for signaling in several cell types, including endothelial cells and skeletal muscle. We used a rat model of orthodontic tooth movement to test the hypothesis that periodontal ligament (PDL) cells communicate stretch to changes in bone cell activity in part via PMD. To produce PMD, we used a 50-g load from a spring activated in the buccal direction against the maxillary first molars for 5 min. Uptake of endogenous serum albumin was used as a PMD marker. Immunohistochemistry demonstrates albumin in PDL cells surrounding moved first molar tips. Image analysis shows significantly more albumin in cells of the buccal side (tension) of the moved teeth compared with those of the lingual, distal, and mesial sides, and those of the unmoved control. Albumin localization within cells of the PDL, after only 5 min of mechanical loading, suggests that PMD could promote uptake or release of signaling molecules.