Figure 3

SERCA were inhibited using 1 μM cyclopiazonic acid leading to a net Ca²⁺-efflux out of the ER. The resulting increase in [Ca²⁺]_c was used as an estimate of the [Ca²⁺]_ER and expressed as percentage of NHBE. (A) In EPLC and LCLC cells in which Ca²⁺-influx contributed to the ATP-induced Ca²⁺-increase the [Ca²⁺]_ER was equal to the [Ca²⁺]_ER of NHBE. (B) In H1339 and HCC cells in which the Ca²⁺-influx did not contribute to the ATP-induced Ca²⁺-increase the ER Ca²⁺-content was lower than in NHBE cells (n = 50 – 153 cells, * = P < 0.001 versus all other groups).