Characterization of the potassium channel from frog skeletal muscle sarcoplasmic reticulum membrane.

Abstract

1. The sarcoplasmic reticulum (SR) membrane of skeletal muscle contains potassium channels which are thought to support charge neutralization during calcium release by providing a permeability pathway for counter-ion movement. To describe the behaviour of the SR K+ channel under physiological conditions, single channel activity was recorded from excised patches of SR membrane. Patches were made from membrane blebs extruded from contracted muscle fibres whose surface membranes had been removed previously by mechanical dissection. 2. The channel was active over a large voltage range from -80 to +100 mV. Ca2`release channel, the SR membrane is known to retard continued Ca2+ efflux (Miller, 1978;Oetliker, 1982).contain ion channels selective for monovalent cations and Thus, the existence of permeability pathways for counteranions (Meissner, 1983;Miller, Bell & Garcia, 1984; Hals, ion movement is thought to be essential for maintaining Stein & Palade, 1989). These channels are thought to allow the large Ca2" flux that occurs during muscle activation.

Polycystin-2 Is a Novel Cation Channel Implicated in Defective Intracellular Ca2+ Homeostasis in Polycystic Kidney Disease

“…same kinetics and other characteristics. This channel was blocked by an agent, bis-guanidino-n-decane (BGD) that has previously been used as an effective blocker of the ER K ϩ channels 21 ( Fig. 1f) but the same agent did not affect the activity of PC2 (Fig.…”

Lotus japonicusCASTOR and POLLUX Are Ion Channels Essential for Perinuclear Calcium Spiking in Legume Root Endosymbiosis

“…In analogy to the role of potassium transporters in calcium signature formation in animal systems, there are at least two possible mechanisms by which CASTOR and POLLUX could contribute to Ca 2+ spiking, and these are not mutually exclusive. The high conductance of CASTOR is similar to that of the potassium channels acting as counter-ion channels balancing the calcium charge released from the sarcoplasmic reticulum (Wang and Best, 1994). CASTOR and POLLUX may act as counter-ion channels facilitating an influx of potassium, which compensates for the rapid release of positive charge from the calcium store during each spike.…”

Muscle and motor-skill dysfunction in a K+ channel-deficient mouse are not due to altered muscle excitability or fiber type but depend on the genetic background

“…Hence, the absence of Kv3.1 K + channels (or subunits) from the SR might lower or abolish counter-ion flux and decrease rapid calcium release, possibly explaining the decrease in contractile force. Although K + channels in skeletal muscle SR have been observed, they have different properties from the homotetrameric Kv3.1 K + channel [15,23,30]. At present, it is not clear if Kv3.1 K + channels or subunits are present in skeletal muscle SR.…”