Korean Journal of Nephrology 1993;12(4):523-532.

고농도의 당이 백서 메산지움 배양세포내 Phospholipase A2 활동도에 미치는 영향

최규헌

Abstract

In order to evaluate the changes of phospholipase A, (PLA,) activity in mesangial cells that might occur in diabetic status, we measured arachidonic acid (A.A.) release, ionomycin (10 pM)- and PMA (phorbol myris- tate acetate: 300 nM)-induced A.A. release, and PLA, activity after 24-and 48-hour exposures to high glucose concentrations (20, 50mM) in cultured rat mesangial cells, and also examined the effects of high hlucose concentration on activation of PLA, following hor- monal stimulation (PMA 300 nM, Arginine vasopressin: AVP 100nM, Epidermal growth factor: EGF 100nM), compared to normal glucose concentration (5 mM). The following results were obtained: 1) Mesangial cells treated with medium containing high glucose for 24 or 48 hours displayed significant increase in A.A. release, compared with cells treated with normal glucose (20 mM: 2.4±0.4% vs 3.7±0.3, 2.2± 0.2 vs 4.0±0.6, 50 mM: 2.2±0.2 vs 4.0±0.6, 3.8±0.5, p<0. 05), but there was so no significant difference in A.A. release between 20 and 50 mM glucose treated group. 2) After 24-and 48-hour growth in high glucose, the activities of PLA, in mesangial cells were not signifi- cantly different from the values in normal glucose (20 mM:25.5±5.1pmol/min/mg of protein vs 21.5±4.4, 19. 7±4.8, 50 mM: 24.9±5.8 vs 19.2±6.0, 22.5±3.7, p>0.05), and the difference between 20 and 50 mM glucose treated group was also not significant. 3) Concerning the effects of ionomycin and PMA on A.A. release, both of them stimulated the release of A.A. markedly from mesangial cells cultured in normal and high glucose concentration for 24 hours (normal glucose: 2.7±0.3% vs ionomycin 11.4±3.8, PMA 5.8±21.1, ionomycin+PMA 12.2±2.8, p<0.05; 20 mM: 3.8±0.4 vs 8.9± 1.8, 6.0± 0.7, 12.1± 0.4; 50 mM: 4.0± 0.3 vs 9.3± 1.1, 6. 1±1.3, 13.1±0.7), but there was no further increase when agents were added after 24-hour growth in high glucose concnetration. 4) Mesangial cells treated with PMA, AVP and EGF showed significant increase of PLA, activity after 24 -hour growth in normal and high glucose concentration (normal glucose: 22.1+5.8 pmol/min/mg of protein vs 40.7±7.5, 34.3±5.9, 36.2±8.4; 20 mM 19.1±6.4 vs 37.5±7. 5, 28.6±6.8, 31.0±6.1, p<0.05), but high glucose had no significant effect on PMA, AVP, and EGF-induced enhancement of PLA, activity. From the above results, it seems that mesangial cell exposure to high concentrations of glucose lead to increase in A.A. release without enhanced activity of PLAsuggestive of A.A. release through the other pathway such as DAG lipase, and hormonal regulatory pathway of PLA, appears not to be significantly influenced by exposure to high glucose.