Figure 6.

XeC inhibits store depletion-induced CCE in the absence of 5-HT in canine PASMCs. (a) Effect of extracellular Ca²⁺ removal, 10 μM CPA, 10 μM ryanodine on cytosolic [Ca²⁺] during extracellular Ca²⁺ re-addition. (b) Effect of 20 μM XeC on cytosolic [Ca²⁺] during extracellular Ca²⁺ re-addition following depletion of the SR Ca²⁺ stores in the absence of 5-HT. (c) Bars indicate the cytosolic [Ca²⁺]. Dashed line shows resting cytosolic [Ca²⁺]. There was a significant difference between the increase in cytosolic [Ca²⁺] induced by store depletion, in the absence (n=38) and presence (n=47) of 20 μM XeC using an unpaired t-test (^**P<0.001). Bars represent means±s.e.m. 5-HT, 5-hydroxytryptamine; CCE, capacitative Ca²⁺ entry; CPA, cyclopiazonic acid; PASMCs, canine pulmonary arterial smooth muscle cells; SR, sarcoplasmic reticulum; XeC, xestospongin-C.