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Preferential role of intracellular Ca 2+ stores in regulation of isometric force in NIH 3T3 fibroblast fibres
Author(s) -
Nobe Koji,
Nobe Hiromi,
Obara Kazuo,
Paul Richard J.
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.00669.x
Subject(s) - cyclopiazonic acid , endoplasmic reticulum , ryanodine receptor , thapsigargin , isometric exercise , intracellular , chemistry , fibroblast , caffeine , biophysics , calcium , medicine , endocrinology , biology , biochemistry , in vitro , organic chemistry
1 Fibroblast contraction plays a major role in wound repair, but the regulatory mechanisms are not well known. We investigated the relations between isometric force and intracellular calcium concentration ([Ca 2+ ] i ) in fibroblast fibres. These fibres were made with mouse NIH 3T3 fibroblasts cultured with native collagen in a three‐dimensional matrix. 2 Calf serum (CS; 30 %) elicited a monotonic increase in force that attained a maximum within 15 min and could be sustained indefinitely. In contrast, [Ca 2+ ] i increased to a peak at 3 min after CS stimulation, then returned to baseline levels by 10 min. Pretreatment with Ca 2+ ‐free medium or the Ca 2+ ‐channel antagonist nicardipine (10 μM) blocked the CS‐induced [Ca 2+ ] i increase, but force was not affected. 3 KCl (50 mM) stimulation on the other hand, elicited a prolonged increase in [Ca 2+ ] i but did not increase force. 4 Inhibition of the endoplasmic reticulum Ca 2+ release with Ca 2+ ‐ATPase inhibitors cyclopiazonic acid (5 μM) or thapsigargin (5 μM) nearly abolished (< 20 % control) the increase in [Ca 2+ ] i and force response to CS. Treatment with ryanodine (10 μM) and caffeine (20 mM) had a similar effect. The phospholipase C inhibitor U73122 (3 μM) reduced the CS‐induced increases in [Ca 2+ ] i and force by 70 and 40 %, respectively. 5 We conclude that fibroblast isometric force is not coupled to Ca 2+ arising from transmembrane influx but is correlated with the transient [Ca 2+ ] i increase due to release from intracellular stores. Store‐released Ca 2+ may initiate activation pathways for fibroblast force development, but is not required for force maintenance.