Role of mitochondria in modulation of spontaneous Ca2+ waves in freshly dispersed interstitial cells of Cajal from the rabbit urethra.

Sergeant, Gerard P. and Bradley, Eamonn and McHale, Noel G. and Hollywood, Mark A. (2008) Role of mitochondria in modulation of spontaneous Ca2+ waves in freshly dispersed interstitial cells of Cajal from the rabbit urethra. Journal of Physiology, 586 (19). pp. 4631-4642.

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Interstitial cells of Cajal (ICC) isolated from the rabbit urethra exhibit pacemaker activity that results from spontaneous Ca(2+) waves. The purpose of this study was to investigate if this activity was influenced by Ca(2+) uptake into mitochondria. Spontaneous Ca(2+) waves were recorded using a Nipkow spinning disk confocal microscope and spontaneous transient inward currents (STICs) were recorded using the whole-cell patch clamp technique. Disruption of the mitochondrial membrane potential with the electron transport chain inhibitors rotenone (10 microm) and antimycin A (5 microm) abolished Ca(2+) waves and increased basal Ca(2+) levels. Similar results were achieved when mitochondria membrane potential was collapsed using the protonophores FCCP (0.2 microm) and CCCP (1 microm). Spontaneous Ca(2+) waves were not inhibited by the ATP synthase inhibitor oligomycin (1 microm), suggesting that these effects were not attributable to an effect on ATP levels. STICs recorded under voltage clamp at -60 mV were also inhibited by CCCP and antimycin A. Dialysis of cells with the mitochondrial uniporter inhibitor RU360 (10 microm) also inhibited STICS. Stimulation of Ca(2+) uptake into mitochondria using the plant flavonoid kaempferol (10 microm) induced a series of propagating Ca(2+) waves. The kaempferol-induced activity was inhibited by application of caffeine (10 mm) or removal of extracellular Ca(2+), but was not significantly affected by the IP(3) receptor blocker 2-APB (100 microm). These data suggest that spontaneous Ca(2+) waves in urethral ICC are regulated by buffering of cytoplasmic Ca(2+) by mitochondria.

Item Type: Article
Uncontrolled Keywords: Interstitial cells; Mitochondria; Ca(2+) waves; Animals; Antimycin A/pharmacology; Caffeine/pharmacology; Calcium/metabolism; Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone/pharmacology; Cells, Cultured; Central Nervous System Stimulants/pharmacology; Electron Transport Complex I/antagonists & inhibitors; Electron Transport Complex III/antagonists & inhibitors; Female; Kaempferols/pharmacology; Male; Membrane Potentials; Mitochondria/drug effects; Mitochondria/metabolism; Muscle, Smooth/cytology; Muscle, Smooth/metabolism; Patch-Clamp Techniques; Rabbits; Rotenone/pharmacology; Urethra/cytology; Urethra/metabolism
Subjects: Science
Research Centres: Smooth Muscle Research Centre
Depositing User: Concepta Woods
Date Deposited: 07 Mar 2012 10:01
Last Modified: 11 Nov 2014 16:10

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