TY - JOUR
T1 - Spatial and temporal aspects of calcium sparks in porcine tracheal smooth muscle cells
AU - Pabelick, Christina M.
AU - Prakash, Y. S.
AU - Kannan, Mathur S
AU - Sieck, Gary C.
PY - 1999/11
Y1 - 1999/11
N2 - Spontaneous, localized intracellular Ca2+ concentration ([Ca2+](i)) transients (Ca2+ sparks) in skeletal, cardiac, and smooth muscle cells are thought to represent Ca2+ release through ryanodine-receptor (RyR) channels. In porcine tracheal smooth muscle (TSM) cells, ACh induces propagating [Ca2+](i) oscillations that also represent Ca2+ release through RyR channels. We used real-time confocal imaging to examine the spatial and temporal relationships of Ca2+ sparks to propagating [Ca2+](i) oscillations in TSM cells. Ca2+ sparks within an intracellular region displayed different spatial Ca2+ distributions with every occurrence. The amplitudes of Ca2+ sparks within a region were approximately integer multiples of the smallest response. However, across different regions, the attributes of Ca2+ sparks varied considerably. Individual sparks were often grouped together and coupled across adjacent regions. Fusion of individual sparks produced large local elevations in [Ca2+](i) that occasionally triggered a propagating [Ca2+](i) wave. The incidence of sparks was increased by ryanodine and caffeine but was unaffected by removal of extracellular Ca2+. Exposure to ACh triggered repetitive, propagating [Ca2+](i) oscillations that always originated from loci with a high spark incidence. The [Ca2+](i) oscillations disappeared with the removal of ACh, and Ca2+ sparks reappeared. We conclude that agonist-induced [Ca2+](i) oscillations represent a spatial and temporal integration of local Ca2+-release events through RyR channels in TSM cells.
AB - Spontaneous, localized intracellular Ca2+ concentration ([Ca2+](i)) transients (Ca2+ sparks) in skeletal, cardiac, and smooth muscle cells are thought to represent Ca2+ release through ryanodine-receptor (RyR) channels. In porcine tracheal smooth muscle (TSM) cells, ACh induces propagating [Ca2+](i) oscillations that also represent Ca2+ release through RyR channels. We used real-time confocal imaging to examine the spatial and temporal relationships of Ca2+ sparks to propagating [Ca2+](i) oscillations in TSM cells. Ca2+ sparks within an intracellular region displayed different spatial Ca2+ distributions with every occurrence. The amplitudes of Ca2+ sparks within a region were approximately integer multiples of the smallest response. However, across different regions, the attributes of Ca2+ sparks varied considerably. Individual sparks were often grouped together and coupled across adjacent regions. Fusion of individual sparks produced large local elevations in [Ca2+](i) that occasionally triggered a propagating [Ca2+](i) wave. The incidence of sparks was increased by ryanodine and caffeine but was unaffected by removal of extracellular Ca2+. Exposure to ACh triggered repetitive, propagating [Ca2+](i) oscillations that always originated from loci with a high spark incidence. The [Ca2+](i) oscillations disappeared with the removal of ACh, and Ca2+ sparks reappeared. We conclude that agonist-induced [Ca2+](i) oscillations represent a spatial and temporal integration of local Ca2+-release events through RyR channels in TSM cells.
KW - Ryanodine
KW - Sarcoplasmic reticulum
KW - Second messenger
UR - http://www.scopus.com/inward/record.url?scp=0032761977&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032761977&partnerID=8YFLogxK
U2 - 10.1152/ajplung.1999.277.5.l1018
DO - 10.1152/ajplung.1999.277.5.l1018
M3 - Article
C2 - 10564188
AN - SCOPUS:0032761977
SN - 1040-0605
VL - 277
SP - L1018-L1025
JO - American Journal of Physiology - Lung Cellular and Molecular Physiology
JF - American Journal of Physiology - Lung Cellular and Molecular Physiology
IS - 5 21-5
ER -