Aim To explore the effects of Angiotensin II on the activities of Ca2+-ATPase, Na+, K+-ATPase and mRNA expression levels of the plasma membrane Ca2+-ATPase isoform 1 (PMCA1) and Na+, K+-ATPase α1-subunit in cultured thoracic aortic vascular smooth muscle cells (AMSCs) from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR).
Methods AMSCs isolated from 14-week-old male WKY rats and SHR were cultured and treated with different concentrations (1×10−9, 1×10−8, 1×10−7 mol/l) of Angiotensin II. The activities of Ca2+-ATPase, Na+, K+-ATPase were measured by biochemistry and enzymology. RT-PCR assay was employed to determine the relative levels of PMCA1 and Na+, K+-ATPase α1-subunit mRNA in AMSCs.
Results Low and moderate concentration of Angiotensin II significantly increased the activity of Ca2+-ATPase and up-regulated PMCA1 mRNA level in AMSCs from Wistar-Kyoto rats, while high concentration of Angiotensin II inhibited Ca2+-ATPase activity and down-regulated PMCA1 mRNA level. Three different concentration of Angiotensin II significantly decreased the activity of Ca2+-ATPase and PMCA1 mRNA level in AMSCs from SHR. Three different concentrations of Angiotensin II stimulated the activity of Na+, K+-ATPase and increased its α1-subunit mRNA expression in AMSCs from WKY rats. Low and moderate concentration of Angiotensin II did not affect the activity of Na+, K+-ATPase in SHR, while high concentration of Angiotensin II significantly suppressed the activity and α1-subunit mRNA level of Na+, K+-ATPase.
Conclusions In WKY rats, Angiotensin II may have biphasic effects on Ca2+-ATPase activity and PMCA1 mRNA expression, and may promote the activity and α1 subunit mRNA expression of Na+, K+-ATPase in a dose-dependent manner in AMSCs. In SHR, Angiotensin II can inhibit Ca2+-ATPase activity and PMCA1 mRNA expression, and only high dose of Angiotensin II can suppress the activity and α1 subunit mRNA expression of Na+, K+-ATPase in AMSCs.