Effects of retinoic acid on the growth of cultured rabbit articular chondrocytes: Relation with alkaline phosphatase activity and beta receptor.

The effects of retinoic acid (RA) on rabbit articular cartilage cells were studied for concentrations ranging from 5.10(-5) M to 10(-7) M; the treatment with RA over three days resulted in dose dependent inhibition of chondrocyte proliferation between 5.10(-5) and 10(-5) M with persistence of the inhibitory effect until 10(-6) M.

Sodium butyrate-induced structural and functional modifications in proteins of cultured rabbit articular chondrocytes.

The effects of sodium butyrate (NaB), a potent growth inhibitory agent, on actin distribution, alkaline phosphatase (AP) activity and protein content were studied in rabbit articular chondrocytes in monolayer culture. When growth of randomly proliferating cells was arrested with NaB, actin stress fibers appeared; at the same time, vimentin-containing intermediate filaments and tubulin-containing microtubules were dispersed. Concomitantly, membrane AP activity and protein content were increased.

G2 arrest, binucleation, and single-parameter DNA flow cytometric analysis.

One important facet of flow cytometry involves the effects of pharmacological agents on cell cycle progression. Comparative G2 fraction perturbations were examined: effects of sodium butyrate on articular chondrocytes, effects of an antineoplastic agent (SOAZ) and an antirheumatic drug (D-penicillamine) on HeLa cells. Even though DNA flow cytometric analysis detects preferentially an induction of G2 arrest, the mode of action of these agents on the cell cycle is different.

Age-related changes in rabbit articular chondrocytes.

Cell culture techniques have been used extensively in the study of the aging process at the cellular level. The "senescent" articular chondrocyte seems to be a good model to examine the responses to aging in osteoarthritis, one of the most frequent diseases of old age. Thus in vitro chondrocyte "senescence", established by weekly subculture was characterized by a declining proliferation rate during late passages, from a rapid growth rate in early subculture to a complete loss of the proliferation capacity after 8 +/- 1 passages.

Sodium butyrate-induced changes in cultured rabbit articular chondrocyte transmembrane electrical potentials. Relationship between these changes and the proliferative response.

Sodium butyrate at 5mM reversibly induced a significant increase of transmembrane potentials (Em) in normal chondrocytes (24 hours after seeding) and arrested their proliferation. This increase in Em levels, which could be temporarily abolished by Tetra-ethyl Ammonium (TEA 5mM), was related to an increase in membrane permeability to K+. This hyperpolarization was correlated with the reversible inhibition of growth in G1 induced by the sodium butyrate.