Genistein inhibits Na+/Ca2+ exchange activity in primary rat cortical neuron culture.
We have examined the possible regulatory effect of tyrosine kinase activity on Ca2+ transport observed in the cultured rat cortical neurons. Na+/Ca2+ exchange was studied using cells cultured for various time periods. A nearly two fold increase in Ca2+ uptake was seen when comparing 3 day and 9 day cultures. Western blot analysis also showed a two fold increase in Na+/Ca2+ exchanger (NCX1) protein levels as cells matured in culture. To study the effect of genistein (a specific tyrosine kinase inhibitor) cells were incubated with 100 microM genistein (in 1% DMSO) for 1 hour before the assay of Na+/Ca2+ exchange activity. There was a significant decrease of Ca2+ uptake in genistein treated neurons (control: 4.596+/-0.205 nmol/mg protein/15 min, n=12; genistein: 1.420+/-0.131 nmol/mg protein/15 min, n=12, mean+/-S.E. P<0.001). Daidzein, an inactive analog of genistein and phorbol myristate acetate (PMA), a PKC activator were without effect. The results suggest that as cells mature in culture, Na+/Ca2+ exchange capacity increases, as a result of greater protein expression. Exposure to genistein inhibited Ca2+ uptake suggesting that the exchanger may be modulated by tyrosine phosphorylation.
Wang
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C
Program in Neurobiology, Department of Biological Sciences, Ohio University College of Osteopathic Medicine, Athens 45701, USA.
Davis
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N
Colvin
R A
RA
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger
D002352:Carrier Proteins; D007529:Isoflavones; D019831:Sodium-Calcium Exchanger; D012964:Sodium; D019833:Genistein; D002118:Calcium