Regulation of [Ca2+]i in canine airway smooth muscle by Ca(2+)-ATPase and Na+/Ca2+ exchange mechanisms

We investigated Ca2+ handling in airway smooth muscle (SM) using fura 2 fluorescence, ion currents, and contractions as indexes of intracellular Ca2+ concentration ([Ca2+]i). Carbachol evoked a transient elevation of [Ca2+]i, the magnitude of which was smaller and the rate of decay faster at 37 degrees C, indicating that some temperature-sensitive mechanism contributed to recovery. Removal of external Na+ had no effect on agonist-evoked Ca2+ …