+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Calcium-dependent inactivation of L-type calcium channels in planar lipid bilayers



Calcium-dependent inactivation of L-type calcium channels in planar lipid bilayers



Biophysical Journal 66(4): 1051-1060



Intracellular Ca2+ can inhibit the activity of voltage-gated Ca channels by modulating the rate of channel inactivation. Ca(2+)-dependent inactivation of these channels may be a common negative feedback process important for regulating Ca2+ entry under physiological and pathological conditions. This article demonstrates that the inactivation of cardiac L-type Ca channels, reconstituted into planar lipid bilayers and studied in the presence of a dihydropyridine agonist, is sensitive to Ca2+. The rates and extents of inactivation, determined from ensemble averages of unitary Ba2+ currents, decreased when the calcium concentration facing the intracellular surface of the channel ([Ca2+]i) was lowered from approximately 10 microM to 20 nM by the addition of Ca2+ chelators. The rates and extents of Ba2+ current inactivation could also be increased by subsequent addition of Ca2+ raising the [Ca2+]i to 15 microM, thus demonstrating that the Ca2+ dependence of inactivation could be reversibly regulated by changes in [Ca2+]i. In addition, reconstituted Ca channels inactivated more quickly when the inward current was carried by Ca2+ than when it was carried by Ba2+, suggesting that local increases in [Ca2+]i could activate Ca(2+)-dependent inactivation. These data support models in which Ca2+ binds to the channel itself or to closely associated regulatory proteins to control the rate of channel inactivation, and are inconsistent with purely enzymatic models for channel inactivation.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 008257277

Download citation: RISBibTeXText

PMID: 8038377

DOI: 10.1016/s0006-3495(94)80886-0


Related references

Voltage-dependent inactivation of T-tubular skeletal calcium channels in planar lipid bilayers. Journal of General Physiology 97(2): 393-412, 1991

Cardiac calcium channels in planar lipid bilayers. L-type channels and calcium-permeable channels open at negative membrane potentials. Journal of General Physiology 92(1): 27-54, 1988

Calcium and calcineurin increase the inactivation rate of l type calcium channels in planar bilayers. Society for Neuroscience Abstracts 16(2): 1174, 1990

Voltage-dependent calcium channels from brain incorporated into planar lipid bilayers. Nature 308(5954): 77-80, 1984

Voltage-dependent calcium channels from Paramecium cilia incorporated into planar lipid bilayers. Science 225(4660): 427-428, 1984

Regulation of cardiac L-type calcium channels in planar lipid bilayers by G proteins and protein phosphorylation. American Journal of Physiology 264(6 Part 1): C1473-C1479, 1993

Okadaic acid and heparin help sustain the activity of l type calcium channels in planar lipid bilayers. Society for Neuroscience Abstracts 17(1-2): 773, 1991

Interaction of luminal calcium and cytosolic ATP in the control of type 1 Ins P3 receptor Study of channels reconstituted in planar lipid bilayers. Biophysical Journal 78(1 Part 2): 314A, 2000

Increase in open probability and lifespan of cardiac L-type calcium channels in planar lipid bilayers by protein kinases, G-proteins, and phosphatase inhibitors. Circulation 86(4 Suppl. 1): I343, 1992

Single calcium channels from rat brain in planar lipid bilayers. Progress in Clinical and Biological Research 168: 59-64, 1984

Different types of cardiac calcium channels incorporated into planar lipid bilayers. Biophysical Journalpart 2: 176a, 1986

Incorporation of several calcium channels from sheep and rabbit heart into planar lipid bilayers. Journal of Physiology (Cambridge) 381: 115P, 1986

Calcium channels in planar lipid bilayers: insights into mechanisms of ion permeation and gating. Science 231(4745): 1564-1566, 1986

Pharmacological profile of skeletal muscle calcium channels in planar lipid bilayers. Biophysical Journal 53(2 Part 2): 555A, 1988

Purified calcium channels from transverse tubule membranes incorporated into planar lipid bilayers. Journal of General Physiology 88(6): 58A, 1986