Fig. 5. Sarcolemmal Ca²⁺-regulatory proteins modulate Ca²⁺-cycling in S100A1-treated NVCMs. (A) Caffeine-induced Ca²⁺-transient amplitudes reveal that overexpressed S100A1 (AdS100A1) enhances SR Ca²⁺-content, whereas SR Ca²⁺-levels are reduced in S100A1-treated cells compared with control cells exposed to caffeine. (B) The elimination of caffeine-releasable SR Ca²⁺ indicated by the decay-constant is similar in caffeine-treated control cells and S100A1-overexpressing cells. However, the decay of the Ca²⁺-transient is accelerated in S100A1-treated NVCMs compared with control cells. (C) Switching to sodium/calcium-free medium abrogates decay acceleration in S100A1-treated cells. ^*P<0.01 vs. control. n=50 cells in AdS100A1 and S100A1-treated cells, control (mock- and Adcontrol-treated NVCMs) n=100 cells, cells from each group were obtained from three independent cell preparations. Data are given as mean±s.e.m.