Abstract: Objective To explore the effect of ouabain on intracellular Ca2 + concentration ([Ca2 + ]i) in thoracic aorta vascular
smooth muscle cells (VSMCs) in vitro. Methods Primary SD rat thoracic aorta VSMCs were cultured by tissue adherent method
and identified by immunochemistry. The binding ability between ouabain and VSMCs was detected by autoradiography, and
fluo 3-AM (a Ca2 + fluorescent probe) was employed to investigate whether ouabain affected VSMCs within a short period of
time. The effect of a truncated fragment of the sodium pump α2 subunit was assayed in antagonizing the effect of ouabain on
[Ca2+]i in the VSMCs. Results Within the concentration range of 0.1-100 nmol/L, ouabain was found to dose-dependently bind
to the VSMCs. Different concentrations of ouabain (0-3200 nmol/L) caused a transient, dose-dependent increase in [Ca2 + ]i in
the VSMCs, which was antagonized by the application of the truncated fragment of sodium pump α2 subunit. Conclusions
Elevations in [Ca2+]i in the VSMCs can be the cytological basis of high ouabain-induced hypertension. The truncated fragment
of the sodium pump α2 subunit can antagonize ouabain-induced increase of [Ca2 + ]i in the VSMCs, which provides a clue for
understanding the pathogenesis of and devising a therapeutic strategy for high ouabain-induced hypertension.