ISSN:
1432-1424
Keywords:
calcium pump
;
sarcoplasmic reticulum
;
calcium channel
;
ryanodine receptor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary Calcium conducting channels were studied in blebs of sarcoplasmic reticulum described by Stein & Palade (1988). The calcium channels had at least three conductance states (70 pS, 50 pS and 37 pS) and were weakly selective for calcium ions, with a permeability ratio Ca2+ to K+ of about 3.4. The open probability of the channel was strongly voltage dependent, decreasing at positive membrane voltages. 10 μm ryanodine and 5 μm ruthenium red had no effect on this channel; neither did millimolar concentrations of ATP, Mg2+, caffeine, and Ca2+, implying that the calcium conducting channels are not ryanodine receptors. Several calcium pump inhibitors—namely, vanadate, AlF 4 − , reactive red 120, and cyclopiazonic acid—had obvious effects on the calcium conducting channels, suggesting that the calcium conducting channel of SR membrane blebs is some form of the SR calcium pump. We thank the National Science Foundation for steadfast support.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00231894
Permalink
