Aim To study the effects of endothelin-1 (ET-1) and BQ-123 (ETA receptor antagonist) on activities and mRNA expression of ATPase in aortic smooth muscle cells (ASMCs) from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats.
Methods The ASMCs were isolated from SHR and WKY rats. The ATPase activities of cultured ASMCs were determined by spectrophotography. The mRNA levels of Na+, K+-ATPase α1-subunit and plasma membrane Ca2+-ATPase isoform 1 (PMCA1) were measured by semiquantitative reverse transcription PCR (RT-PCR).
Results 3 different concentrations of ET-1 (1×10−9, 1×10−8 and 1×10−7 mol/l) significantly attenuated the activities of Na+, K+-ATPase and Ca2+-ATPase and PMCA1 mRNA expression (all p<0.01) in ASMCs from SHR. Three different concentrations of BQ-123 (1×10−8, 1×10−7 and 1×10−6 mol/l) obviously prevented ET-1 mediated the inhibition of two kinds ATPase activities (all p<0.01) and downregulation of PMCA1 mRNA expression (p<0.01). But the mRNA expression level of Na+, K+-ATPase α1-subunit had no alteration after intervened by ET-1 (p>0.05).
Conclusions ET-1 may suppress Na+, K+-ATPase, Ca2+-ATPase activities via ETA receptor. The influence of ET-1 on Ca2+-ATPase activity may partially occur in the transcriptional level. BQ-123 can inhibit the effect of ET-1 on two kinds ATPase activities of ASMCs in SHR by blocking the ETA receptor.