Acetylcholine (ACh) induces repetitive, propagating intracellular Ca2+ concentration ([Ca2+](i)) oscillations in porcine tracheal smooth muscle (TSM) cells. Using real-time confocal microscopy, we examined the role of sarcoplasmic reticulum (SR) Ca2+ release through inositol 1,4,5- trisphosphate (IP3) receptor and ryanodine receptor (RyR) channels in ACh- induced [Ca2+](i) oscillations. In β-escin permeabilized TSM cells, exposure to ACh in the presence of GTP also resulted in [Ca2+](i) oscillations. [Ca2+](i) oscillations could not be initiated by IP3 alone; however, an elevation of [Ca2+](i) was observed. During ongoing [Ca2+](i) oscillations, exposure to heparin, an IP3 receptor antagonist, caused a slowing of oscillation frequency but not complete inhibition. In contrast, ruthenium red, a RyR antagonist, completely abolished ACh-induced [Ca2+](i) oscillations. Reverse transcriptase-polymerase chain reaction of TSM mRNA demonstrated the expression of RyR-2 and RyR-3 isoforms of the RyR. These results indicate that SR Ca2+ release through RyR channels is critical for ACh-induced [Ca2+](i) oscillations in porcine TSM cells.
|Original language||English (US)|
|Journal||American Journal of Physiology - Lung Cellular and Molecular Physiology|
|Issue number||4 16-4|
|State||Published - Apr 1997|
- confocal microscopy
- sarcoplasmic reticulum
- β- estin