Role of ryanodine receptor channels in Ca2+ oscillations of porcine tracheal smooth muscle.
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 beta-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.
Kannan
M S
MS
Department of Veterinary Pathobiology, University of Minnesota, St. Paul 55108, USA.
Prakash
Y S
YS
Brenner
T
T
Mickelson
J R
JR
Sieck
G C
GC
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D007473:Ion Channels / Q000502:physiology*; D007536:Isomerism; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel; D013552:Swine; D014132:Trachea / Q000166:cytology / Q000378:metabolism*
D015220:Calcium Channels; D007473:Ion Channels; D009124:Muscle Proteins; D012333:RNA, Messenger; D019837:Ryanodine Receptor Calcium Release Channel; D015544:Inositol 1,4,5-Trisphosphate; D000109:Acetylcholine; D002118:Calcium