Cristóvão AJ, Carvalho CA. Ins(1,4,5)P3 induces Ca2+ release from brain microsomes loaded either by the Ca2+ ATPase or by the Na+/Ca2+ exchanger.
Cell Signal 1992;
4:687-96. [PMID:
1489660 DOI:
10.1016/0898-6568(92)90049-e]
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Abstract
In this study we investigated the release of Ca2+ in brain microsomes after Ca2+ loading by the Ca(2+)-ATPase or by the Na+/Ca2+ exchanger. The results show that in microsomes loaded with Ca2+ by the Ca(2+)-ATPase, Ins(1,4,5)P3 (5 microM) released 21 +/- 2% of the total Ca2+ accumulated, and that in the microsomes loaded with Ca2+ by the Na+/Ca2+ exchanger, Ins(1,4,5)P3 released 28 +/- 3% of the total Ca2+ accumulated. These results suggest that receptors of Ins(1,4,5)P3 may be co-localized with the Na+/Ca2+ exchanger in the endoplasmic reticulum membrane or that there are Ins(1,4,5)P3 receptors in the plasma membrane where the Na+/Ca2+ exchanger is normally present, or both. We also found that Ins(1,4,5)P3 inhibited the Ca(2+)-ATPase by 33.7%, but that it had no significant effect on the Na+/Ca2+ exchanger.
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