๐”– Bobbio Scriptorium
โœฆ   LIBER   โœฆ

Activation by intracellular calcium of a potassium channel in cardiac sarcoplasmic reticulum

โœ Scribed by Akira Uehara; Midori Yasukohchi; Shigenori Ogata; Issei Imanaga

Publisher
Springer
Year
1991
Tongue
English
Weight
325 KB
Volume
417
Category
Article
ISSN
0031-6768

No coin nor oath required. For personal study only.

โœฆ Synopsis

The effects of low (pCa 7.5 to 3) concentrations of intracellular calcium ion on a single potassium channel in the sarcoplasmic reticulum of canine heart ventricular muscle were investigated using a planar lipid bilayer technique. The low concentrations were obtained by mixing EGTA and calcium chloride. By varying the pCa of the cytoplasmic face between 3 to 7.5, two novel effects were observed.

First, an increase in the intracellular Ca 2+ concentration produced an increase in the unit current amplitude of open states; the voltage-current relationship was ohmic at these concentrations_ Second, an increase in the Ca 2+ concentration increased the open probability. Both these effects of Ca 2+ were dose-dependent, arid were consistently observed in all channels tested.

Thus, the SR potassium channel observed appears to belong to the class of Ca "+ -activated potassium channels.

๐Ÿ“œ SIMILAR VOLUMES

The role of phospholamban in the regulat
The role of phospholamban in the regulation of calcium transport by cardiac sarcoplasmic reticulum
โœ Bruce A. Davis; Istvan Edes; Ramesh C. Gupta; Ellen F. Young; Hae Won Kim; Nancy ๐Ÿ“‚ Article ๐Ÿ“… 1990 ๐Ÿ› Springer ๐ŸŒ English โš– 418 KB

The calcium transport mechanism of cardiac sarcoplasmic reticulum (SR) is (SR) is regulated by a phosphoregulatory mechanism involving the phosphorylation-dephosphorylation of an integral membrane component, termed phospholamban. Phospholamban, a 27,000 Da proteolipid, contains phosphorylation sites

Positive cooperativity in activation of
Positive cooperativity in activation of the cardiac muscarinic K+channel by intracellular GTP
โœ Yoshihisa Kurachi; Hiroyuki Ito; Tsuneaki Sugimoto ๐Ÿ“‚ Article ๐Ÿ“… 1990 ๐Ÿ› Springer ๐ŸŒ English โš– 232 KB

Concentration-dependent effects of intracellular GTP on activation of the muscarinic K + channel were examined in inside-out patches of cardiac atrial myocytes. The pipette solution contained 0.i ~I ACh. GTP (0.01-30 ~M) and 0.5 mM MgCI 2 were applied to the inside side of the patch membrane. K + ch

Calcium-activated potassium channels in
Calcium-activated potassium channels in the luminal membrane ofAmphiumadiluting segment: voltage-dependent block by intracellular Na+upon depolarisation
โœ Katsumasa Kawahara; Malcolm Hunter; Gerhard Giebisch ๐Ÿ“‚ Article ๐Ÿ“… 1990 ๐Ÿ› Springer ๐ŸŒ English โš– 624 KB

Calcium-activated potassium channels in the luminal membrane of Amphiuma diluting segment were studied using the patch-clamp technique in both the cell-attached and inside-out configurations. The open probability (Po) of the channel is sensitive to both membrane potential and cytoplasmic calcium act