Cyclic nucleotides and growth regulation of the mandibular condylar cartilage of the rat in vitro

By exogenous interference in the intracellular level of cAMP and cGMP during growth in vitro without and with compression, an indication was obtained for the mediatorial involvement of these cyclic nucleotides in the major growth-processes in the mandibular condylar cartilage of 4-day-old rats. Raising the intracellular level of cAMP reduced proliferative activity in the prechondroblast zone, did not affect matrix synthesis by the functional chondroblasts and stimulated the process of hypertrophy. Intracellular elevation of cGMP had an antagonistic effect; it stimulated proliferation as well as matrix synthesis, but had no effect on hypertrophy. In this specific type of cartilage, cGMP can be considered as a major secondary intracellular messenger for proliferation-stimulating continuous biomechanical stimuli.