Cytosol-Free Calcium Concentration in Single Bladder Smooth Muscle Cells from Normal and Diabetic Rats

Pharmacology ◽  
1992 ◽  
Vol 45 (2) ◽  
pp. 90-98 ◽  
Author(s):  
Jin Qi ◽  
Robert M. Curley ◽  
John A. Belis
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Calcium Concentration ◽  
Muscle Cells ◽  
Diabetic Rats ◽  
Free Calcium ◽  
Bladder Smooth Muscle ◽  
Free Calcium Concentration

Role of smooth muscle cells on endothelial cell cytosolic free calcium in porcine coronary arteries

2001 ◽  
Vol 281 (3) ◽  
pp. H1156-H1162 ◽  
Author(s):  
Stéphane Budel ◽  
Alexander Schuster ◽  
Nikos Stergiopoulos ◽  
Jean-Jacques Meister ◽  
Jean-Louis Bény
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Coronary Arteries ◽  
Calcium Concentration ◽  
Muscle Cells ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Free Calcium Concentration ◽  
Cytosolic Free Calcium Concentration

We tested the hypothesis that the cytosolic free calcium concentration in endothelial cells is under the influence of the smooth muscle cells in the coronary circulation. In the left descending branch of porcine coronary arteries, cytosolic free calcium concentration ([Ca2+]i) was estimated by determining the fluorescence ratio of two calcium probes, fluo 4 and fura red, in smooth muscle and endothelial cells using confocal microscopy. Acetylcholine and potassium, which act directly on smooth muscle cells to increase [Ca2+]i, were found to indirectly elevate [Ca2+]i in endothelial cells; in primary cultures of endothelial cells, neither stimulus affected [Ca2+]i, yet substance P increased the fluorescence ratio twofold. In response to acetylcholine and potassium, isometric tension developed by arterial strips with intact endothelium was attenuated by up to 22% ( P < 0.05) compared with strips without endothelium. These findings suggest that stimuli that increase smooth muscle [Ca2+]i can indirectly influence endothelial cell function in porcine coronary arteries. Such a pathway for negative feedback can moderate vasoconstriction and diminish the potential for vasospasm in the coronary circulation.

ATP-dependent control of steady-state cytosolic calcium in cultured gastric smooth muscle

1991 ◽  
Vol 261 (4) ◽  
pp. G634-G640 ◽  
Author(s):  
R. J. Gilbert ◽  
G. Valente ◽  
J. T. Deeney ◽  
B. E. Corkey
Keyword(s):  
Smooth Muscle ◽  
Steady State ◽  
Smooth Muscle Cells ◽  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Muscle Cells ◽  
Free Calcium ◽  
Calcium Sequestration ◽  
Gastric Smooth Muscle ◽  
Free Calcium Concentration

The regulation of intracellular calcium uptake and release in cultured gastric smooth muscle cells was studied in saponin-permeabilized cells derived from the rabbit antrum. Cells were studied in an ATP-regenerating medium in which the value of the ATP-to-ADP ratio was fixed by variation of the relative concentrations of creatine and creatine phosphate in the presence of a constant concentration of adenine nucleotides and creatine kinase. Free calcium in the medium was measured through the use of the fluorescent probe fura-2. As the ratio of ATP/ADP was increased (8.5, 55.0, and 155.0), the rate of calcium sequestration was increased, resulting in a decrease of steady-state free calcium (275.2, 178.4, and 98.1 nM, respectively). The addition of glucose (5 mM) and hexokinase (15 U/ml), which results in an increase of ADP due to the phosphorylation of glucose in the medium, caused an increase of free calcium concentration to a new set point of approximately 400 nM. Mitochondrial blockade with antimycin A before permeabilization had no effect on calcium sequestration or the resultant free calcium concentration, indicating that under physiological conditions calcium is sequestered predominantly into nonmitochondrial storage sites. Specific variation of ATP/ADP had no effect on the concentration dependence of inositol trisphosphate-induced calcium efflux, suggesting the functional independence of intracellular calcium influx and efflux pathways. These results indicate a significant role for cytoplasmic ATP/ADP in the control of intracellular calcium sequestration and the regulation of steady-state calcium concentration in cultured gastrointestinal smooth muscle cells.

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