Abnormal Ca2+ handling and increased Mg2+ permeability in platelets of hypertensive rats

Citation
T. Oshima et al., Abnormal Ca2+ handling and increased Mg2+ permeability in platelets of hypertensive rats, HYPERTENS R, 23(6), 2000, pp. 651-657
Citations number
41
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cardiovascular & Respiratory Systems
Journal title
Hypertension research
ISSN journal
0916-9636 → ACNP
Volume
23
Issue
6
Year of publication
2000
Pages
651 - 657
Database
ISI
SICI code
Abstract
In order to test the hypothesis that intracellular Na+ accumulation and cel lular Mg2+ deficiency may be involved in the abnormalities in Ca2+ handling and reactivity in spontaneously hypertensive rats(SHR) platelets, the meta bolism of Na+, Ca2+ and Mg2+ was determined in fluorescent dye loaded plate lets from 15 SHR and 15 Wistar Kyoto rats (WKY) at 12 weeks of age. Mg2+ le ak was estimated as the Mg2+ influx induced by an increase in extracellular [Mg2+] (from 1 to 5 mmol/l) and Mg2+/Na+ exchange activity was estimated a s the Mg2+ influx induced by a decrease in extracellular [Na+] (from 140 to 50 mmol/l). Cellular metabolism of the fluorescent dye was similar in the two groups. Mean platelet [Ca2+](i) was significantly increased under basal and thrombin (0.1 U/ml)-stimulated conditions in SHR compared to WKY, both in the presence and absence of extracellular Ca2+. Mean Ca2+ discharge cap acity was similar between the two groups. There was no difference in mean [ Na+]i between the two groups. Basal [Mg2+]i was also increased in SHR plate lets. Mg2+ leak was higher in SHR than in WKY, while Mg2+/Na+ exchange acti vity was similar in the two groups. There was no difference in serum Mg2+ c oncentration between SHR and WKY, These data suggest that abnormal Ca2+ han dling is accompanied by elevation in [Mg2+]i via increased permeability of platelet cell membranes to Mg2+ in SHR without any alteration in [Na+]i, an d do not support the Mg2+ deficiency hypothesis in genetically hypertensive rats.