Interactions between large and small bovine luteal cells in a sequential perifusion co-culture system

The objectives of this experiment were to study large and small luteal cell interactions and examine the effect of arachidonic acid (AA) on progesterone production by separated bovine luteal cells. Corpora lutea collected from Holstein cows (n = 5) on d 12 of the estrous cycle were dispersed, and small (SLC) and large (LLC) luteal cells were separated by unit gravity sedimentation and flow cytometry. Cells were incubated at 37 degrees C in separate perifusion chambers with a modified Ham's F-12-HEPES medium and aerated with 95% O2:5% CO2. The flow rate of medium was 100 microL/min, and fractions were collected at 30-min intervals for 4 h. Luteal cells were arranged in tandem so that medium from the first cell type would pass through the chamber containing the second cell type. Luteal cells were arranged so that medium flowed from 1) SLC to SLC, 2) LLC to LLC, 3) SLC to LLC, 4) LLC to SLC, 5) SLC to LLC, 6) LLC to SLC; medium for arrangements 5 and 6 contained 10 microM AA. Cells in arrangements 5 and 6 were perifused for 30 min before AA was added. Progesterone was measured with an enzymeimmunoassay. The LLC to LLC arrangement had a greater (P < .05) average progesterone secretion rate than all other cell arrangements, and the SLC to SLC arrangement had the least progesterone secretion rate.(ABSTRACT TRUNCATED AT 250 WORDS)