Tendon creep is potentiated by NKISK and relaxin which produce collagen fiber sliding.

The pentapeptide NKISK has been reported to inhibit the binding of decorin, a proteoglycan on the surface of collagen fibrils, to fibronectin, a tissue adhesion molecule. Relaxin has been shown to be effective in relaxing ligaments and other connective tissues. Through collagen staining studies, we have previously demonstrated that collagen fiber sliding is important during changes in ligament length. Because of our interest in fibril-fibril binding as it relates to changes in length of tendon or ligament, we investigated the potential of NKISK, relaxin, or both in combination to potentiate creep. We suspended stained rat tail tendons in test solutions under a constant stress and observed length changes and subsequent collagen fiber sliding. Both NKISK and relaxin potentiated rat tail tendon creep with changes in length most likely occurring as a result of collagen fiber sliding as evidenced by photomicrography.