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Cholesterol depletion alters coronary artery myocyte Ca(2+) signalling in a stimulus-specific manner.

Prendergast C, Quayle J, Burdyga T, Wray S - Cell Calcium (2010)

Bottom Line: We have examined the effect of the cholesterol-depleting agents, methyl-cyclodextrin (MCD) and cholesterol oxidase, on high K(+), caffeine and agonist-induced Ca(2+) signals.There was also a significant decrease in cell capacitance.These data are discussed in terms of the involvement of caveolae in receptor localisation, Ca(2+) entry pathways and SR Ca(2+) release, and the role of these in agonist signalling.

View Article: PubMed Central - PubMed

Affiliation: University of Liverpool, Merseyside, UK. c.prendergast@liv.ac.uk

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Related in: MedlinePlus

(A) Representative traces, recorded from the same cell, showing that the increase in outward K+ current induced by MCD is blocked by 100 nM iberiotoxin and (B) mean data showing the effects of 100 nM iberiotoxin, 100 nM TRAM-34 and 100 nM apamin on MCD-induced increases in outward K+ current.
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fig7: (A) Representative traces, recorded from the same cell, showing that the increase in outward K+ current induced by MCD is blocked by 100 nM iberiotoxin and (B) mean data showing the effects of 100 nM iberiotoxin, 100 nM TRAM-34 and 100 nM apamin on MCD-induced increases in outward K+ current.

Mentions: MCD has been reported to elevate basal intracellular Ca2+[16]. Therefore, in order to determine whether this elevation of outward current in the presence of MCD is due to activation of Ca2+-dependent K+ currents, we examined the effects of 3 selective channel blockers: iberiotoxin (100 nM) to block large conductance (BKCa) channels, TRAM-34 (100 nM) to block intermediate conductance (IKCa) channels and apamin (100 nM) to block small conductance (SKCa) channels. The main protocol used to assess the inhibitory nature of these antagonists involved pre-treatment with the blocker and then a challenge with MCD. We also confirmed the result by using MCD first to increase outward current and then applying the blocker on top. Iberiotoxin pre-treatment significantly inhibited the increase in outward current observed with MCD (2.42 ± 0.28-fold, n = 11 versus 1.37 ± 0.16-fold, n = 5, P = 0.029). When cholesterol was depleted with MCD first, iberiotoxin entirely ablated the MCD-induced increase in outward current (Fig. 7A, n = 3). TRAM-34 failed to alter the increase in K+ current observed with MCD using either protocol (Fig. 7B, 2.42 ± 0.28-fold versus 1.97 ± 0.21-fold, n = 5, P = 0.32). Similarly, apamin failed to alter the increase in K+ current observed with MCD (Fig. 7B, 2.42 ± 0.28-fold versus 2.1 ± 0.23-fold, n = 5, P = 0.43). It was confirmed that the DMSO and apamin vehicle controls had no effect on outward current.


Cholesterol depletion alters coronary artery myocyte Ca(2+) signalling in a stimulus-specific manner.

Prendergast C, Quayle J, Burdyga T, Wray S - Cell Calcium (2010)

(A) Representative traces, recorded from the same cell, showing that the increase in outward K+ current induced by MCD is blocked by 100 nM iberiotoxin and (B) mean data showing the effects of 100 nM iberiotoxin, 100 nM TRAM-34 and 100 nM apamin on MCD-induced increases in outward K+ current.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2824115&req=5

fig7: (A) Representative traces, recorded from the same cell, showing that the increase in outward K+ current induced by MCD is blocked by 100 nM iberiotoxin and (B) mean data showing the effects of 100 nM iberiotoxin, 100 nM TRAM-34 and 100 nM apamin on MCD-induced increases in outward K+ current.
Mentions: MCD has been reported to elevate basal intracellular Ca2+[16]. Therefore, in order to determine whether this elevation of outward current in the presence of MCD is due to activation of Ca2+-dependent K+ currents, we examined the effects of 3 selective channel blockers: iberiotoxin (100 nM) to block large conductance (BKCa) channels, TRAM-34 (100 nM) to block intermediate conductance (IKCa) channels and apamin (100 nM) to block small conductance (SKCa) channels. The main protocol used to assess the inhibitory nature of these antagonists involved pre-treatment with the blocker and then a challenge with MCD. We also confirmed the result by using MCD first to increase outward current and then applying the blocker on top. Iberiotoxin pre-treatment significantly inhibited the increase in outward current observed with MCD (2.42 ± 0.28-fold, n = 11 versus 1.37 ± 0.16-fold, n = 5, P = 0.029). When cholesterol was depleted with MCD first, iberiotoxin entirely ablated the MCD-induced increase in outward current (Fig. 7A, n = 3). TRAM-34 failed to alter the increase in K+ current observed with MCD using either protocol (Fig. 7B, 2.42 ± 0.28-fold versus 1.97 ± 0.21-fold, n = 5, P = 0.32). Similarly, apamin failed to alter the increase in K+ current observed with MCD (Fig. 7B, 2.42 ± 0.28-fold versus 2.1 ± 0.23-fold, n = 5, P = 0.43). It was confirmed that the DMSO and apamin vehicle controls had no effect on outward current.

Bottom Line: We have examined the effect of the cholesterol-depleting agents, methyl-cyclodextrin (MCD) and cholesterol oxidase, on high K(+), caffeine and agonist-induced Ca(2+) signals.There was also a significant decrease in cell capacitance.These data are discussed in terms of the involvement of caveolae in receptor localisation, Ca(2+) entry pathways and SR Ca(2+) release, and the role of these in agonist signalling.

View Article: PubMed Central - PubMed

Affiliation: University of Liverpool, Merseyside, UK. c.prendergast@liv.ac.uk

Show MeSH
Related in: MedlinePlus