scholarly journals Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging

Author(s):  
Gabriela Ziomek ◽  
Cornelis van Breemen ◽  
Mitra Esfandiarei
1992 ◽  
Vol 263 (2) ◽  
pp. C535-C539 ◽  
Author(s):  
D. M. Berman ◽  
W. F. Goldman

Cytosolic Ca2+ concentrations ([Ca2+]cyt) and [3H]inositol phosphates ([3H]InsP) were correlated while varying the Ca2+ content of the sarcoplasmic reticulum (SR) in cultured A7r5 cells at rest and during activation with [Arg8]-vasopressin (AVP). Thapsigargin (TG) raised and superfusion with 0 Ca2+ lowered [Ca2+]cyt, but both treatments decreased SR Ca2+ and AVP-evoked Ca2+ transients. Neither TG nor 0 Ca2+ affected basal [3H]InsP, but both treatments increased AVP-evoked synthesis of [3H]InsP. Exposure for several minutes to 40 mM K+ solution, BAY K 8644, or low-Na+ solution all elevated [Ca2+]cyt and, thereby, increased SR Ca2+, as manifested by augmented AVP-evoked Ca2+ transients. In all three cases, AVP-evoked, but not basal, [3H]InsP were reduced. The inhibitory effect of 40 mM K+ on AVP-evoked [3H]InsP synthesis was blocked when SR Ca2+ uptake was prevented by TG. Brief (30-s) exposures to 40 mM K+, which elevated [Ca2+]cyt but not SR Ca2+ loading, did not modify AVP-evoked [3H]InsP synthesis or Ca2+ transients. These results demonstrate an inverse relationship between SR Ca2+ content and evoked [3H]-InsP synthesis. Moreover, they suggest that SR Ca2+ may serve as a signal that modulates sarcolemmal [3H]InsP formation.


1996 ◽  
Vol 16 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Federico Calara ◽  
Sean Ameli ◽  
Anna Hultgårdh-Nilsson ◽  
Bojan Cercek ◽  
Joel Kupfer ◽  
...  

1993 ◽  
Vol 265 (5) ◽  
pp. C1371-C1378 ◽  
Author(s):  
M. P. Walsh ◽  
J. D. Carmichael ◽  
G. J. Kargacin

Calponin isolated from chicken gizzard smooth muscle binds in vitro to actin in a Ca(2+)-independent manner and thereby inhibits the actin-activated Mg(2+)-adenosinetriphosphatase of smooth muscle myosin. This inhibition is relieved when calponin is phosphorylated by protein kinase C or Ca2+/calmodulin-dependent protein kinase II, suggesting that calponin is involved in thin filament-associated regulation of smooth muscle contraction. To further examine this possibility, calponin was isolated from toad stomach smooth muscle, characterized biochemically, and localized in intact isolated cells. Toad stomach calponin had the same basic biochemical properties as calponin from other sources. Confocal immunofluorescence microscopy revealed that calponin in intact smooth muscle cells was localized to long filamentous structures that were colabeled by antibodies to actin or tropomyosin. Preservation of the basic biochemical properties of calponin from species to species suggests that these properties are relevant for its in vivo function. Its colocalization with actin and tropomyosin indicates that calponin is associated with the thin filament in intact smooth muscle cells.


1998 ◽  
Vol 35 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Patricia Sansilvestri-Morel ◽  
Isabelle Nonotte ◽  
Marie-Pierre Fournet-Bourguignon ◽  
Alain Rupin ◽  
Jean-Noël Fabiani ◽  
...  

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