Effect of Hypocalcemic Protein P-MSY obtained from Bovine Parotid Gland on the Cyclic Adenosine-5'-monophosphate and Cyclic Guanosine-5'-monophosphate Contents of Murine Thymus and Spleen Cells

The effect of P-MSY, a hypocalcemic protein from bovine parotid gland, on the levels of cyclic adenosine-5'-monophosphate (cAMP) and cyclic guanosine-5'-monophosphosphate (cGMP) in thymic and splenic cells of 4-week-old C57BL/6 mice was studied in vitro. Preliminary studies on the effect of 0.5mg/ml of P-MSY indicated that an incubation time of 10 min gave the maximum response. This incubation time was used in dose-response studies. In thymic cells, the increase of cAMP content was dose-dependent (2-3.6 fold increase in response to 1 mg/ml P-MSY), but little change of cGMP was observed. The ratio of cAMP/cGMP increased about 1.7-2.5 times at a concentration of 0.2 mg/ml P-MSY. cAMP did not increase as much in the splenic cells as in the thymic cells. The difference between the thymus and spleen in response to P-MSY is probably due to the relatively greater influence of P-MSY on T-cells of the thymus.