Histidine-rich calcium binding protein, a sarcoplasmic reticulum protein of striated muscle, is also abundant in arteriolar smooth muscle cells

1992 ◽  
Vol 13 (3) ◽  
pp. 366-376 ◽  
Author(s):  
Ravindra K. Pathak ◽  
Richard G. W. Anderson ◽  
Sandra L. Hofmann
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Smooth Muscle Cells ◽  
Calcium Binding ◽  
Striated Muscle ◽  
Binding Protein ◽  
Protein A ◽  
Muscle Cells ◽  
Calcium Binding Protein

scholarly journals Direct measurement of Ca2+ uptake and release by the sarcoplasmic reticulum of saponin permeabilized isolated smooth muscle cells.

1995 ◽  
Vol 106 (3) ◽  
pp. 467-484 ◽  
Author(s):  
M E Kargacin ◽  
G J Kargacin
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Smooth Muscle Cells ◽  
Single Cell ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Intact Cells ◽  
Direct Measurements ◽  
Isolated Smooth Muscle Cells ◽  
Uptake And Release

To make direct measurements of Ca2+ uptake and release by the sarcoplasmic reticulum (SR) of isolated smooth muscle cells, a fluorometric method for monitoring Ca2+ uptake by striated muscle SR vesicles (Kargacin, M.E., C.R. Scheid, and T.W. Honeyman. 1988. American Journal of Physiology. 245:C694-C698) was modified. With the method, it was possible to make continuous measurements of SR function in saponin-skinned smooth muscle cells in suspension. Calcium uptake by the SR was inhibited by thapsigargin and sequestered Ca2+ could be released by Br-A23187 and thapsigargin. From the rate of Ca2+ uptake by the skinned cells and the density of cells in suspension, it was possible to calculate the Ca2+ uptake rate for the SR of a single cell. Our results indicate that the SR Ca2+ pump in smooth muscle cells can remove Ca2+ at a rate that is 45-75% of the rate at which Ca2+ is removed from the cytoplasm of intact cells during transient Ca2+ signals. From estimates of SR volume reported by others and our measurements of the amount of Ca2+ taken up by the skinned cells, we conclude that the SR of a single cell can store greater than 10 times the amount of Ca2+ needed to elicit a single transient contractile response.

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