Conclusion
Static or cyclic tensile strain induces acute increases in the abundance of myxomatous effector proteins, TPH1, and markers of chondrogenesis in canine mitral valves. Canine mitral valves are capable of local serotonin synthesis, which may be influenced by strain.
Methods
Mitral valves were placed in culture and subjected to 30% static or cyclic tensile strain and compared to cultured mitral valves subjected to 0% strain for 72 h. Abundance of target effector proteins, TPH1, and chondrogenic marker proteins was determined by immunoblotting. Serotonin was measured in the conditioned media by ELISA.
Results
Both static and cyclic strain increased (p < 0.05) expression of myxomatous effector proteins including markers of an activated myofibroblast phenotype, matrix catabolic and synthetic enzymes in canine mitral valves compared to unstrained control. Expression of TPH1 was increased in statically and cyclically strained mitral valves. Expression of chondrogenic markers was increased in statically strained mitral valves. Serotonin levels were higher (p < 0.05) in media of cyclically strained valves compared to unstrained valves after 72 h of culture.