The effect of environmental pH change on bovine articular cartilage metabolism: implications for the use of buffered...

The purpose of this study is to determine the immediate effects of pH change on the metabolism of bovine chondrocytes.

Bovine osteochondral explants were pre-cultured and placed in Ringer's lactate solution. Thirty explants were randomly divided into 3 groups. Buffered Ringer's lactate, pH 7.2, was used in Group I; buffered Ringer's lactate, pH 7.4 (normal bovine knee joint pH), was used in Group II; and this group was also set as the control group. Buffered Ringer's lactate, pH 7.6, was used in Group III. All specimens were soaked for 2 h. RNA yield analyses were performed to evaluate the changes in cartilage metabolism at different pH levels.

Mean RNA yields of (hypoxia-induced factor) 1α that were immersed at pH 7.2 and 7.6 were 10.5- and 9.9-fold from base, respectively, which were lower compared to explants at pH 7.4 which was found as 15.2-fold. Mean RNA yields of aggrecan that were immersed at pH 7.2 and 7.6 were 12.2- and 13.6-fold from base, respectively, which were lower compared to explants at pH 7.4 which was found as 20-fold. RNA yields of collagen type II at pH 7.2 and 7.6 were 16.1- and 16.6-fold from base, respectively, which were lower compared to explants immersed at pH 7.4 which was found as 22.1-fold.

The findings of the presented study suggest that short-term exposures to both acidic and basic pH may have effects on chondrocyte function. Our findings also indicate that exposures to solutions with a pH different from normal by only 0.2 unit could suppress chondrocyte metabolism and RNA synthesis.

Using buffered irrigation solutions with a pH closer to the normal joint pH could be more physiologic and causes less ultra-structural damage than regular irrigation solutions.

II.