ATP-regulated K+ channels in cardiac muscle

  title={ATP-regulated K+ channels in cardiac muscle},
  author={Akinori Noma},
  • A. Noma
  • Published 8 September 1983
  • Biology, Medicine
  • Nature
An outward current of unknown nature increases significantly when cardiac cells are treated with cyanide or subjected to hypoxia1–4, and decreases on intracellular injection of ATP5. We report here that application of the patch-clamp technique to CN-treated mammalian heart cells reveals specific K+ channels which are depressed by intracellular ATP (ATPi) at levels greater than 1 mM. For these channels, conductance in the outward direction is much larger than the inward rectifier K+ channel… 
Properties of cardiac ATP-sensitive potassium channels
It has long been known that the cardiac action potential shortens during ischemia or hypoxia and that this shortening results primarily from an increased potassium conductance [1]. About ten years
Glycolysis preferentially inhibits ATP-sensitive K+ channels in isolated guinea pig cardiac myocytes.
In this study the patch-clamp technique was used to study potassium channels sensitive to intracellular ATP levels in permeabilized ventricular myocytes and showed that glycolysis was more effective than oxidative phosphorylation in preventing ATP-sensitive K+ channels from opening.
Modulation of ATP-sensitive K+ channels in skeletal muscle by intracellular protons
Evidence is presented that a decrease in intracellular pH (pHi) markedly reduces the inhibitory effect of ATP on KATP channels in excised patches from frog skeletal muscle.
ATP‐sensitive K+ channel modification by metabolic inhibition in isolated guinea‐pig ventricular myocytes.
The purpose of this study was to determine whether the K+ATP channel itself is intrinsically altered by the processes associated with metabolic impairment, and found that in metabolically inhibited myocytes elevated [Ca2+]i acted indirectly.
Regulation of K+ channels in cardiac myocytes by free fatty acids.
Since the level of free fatty acids rises after longer periods of ischemia, it is speculated that the ATP-insensitive K+ channel contributes to the late or secondary phase of extracellular K+ accumulation.
Metabolic regulation of cardiac ATP-sensitive K+ channels
It is hypothesized that sarcolemma-associated glycolytic enzymes may be important in maintaining a high local cytosolic ATP/ADP ratio in the vicinity of KATP channels, where sarcolemmal ATPases are tending to depress the local ATP/ ADP ratio.
Therapeutic Potential of ATP-Sensitive K+ Channel Openers in Cardiac Ischemia
ATP-sensitive K+ (KATP) channels were originally described in cardiac myocytes (Noma, 1983), and since their discovery, they have been shown in brain, smooth muscle, kidneys, pancreatic β-cells, and
Angiotensin II blocks ATP-sensitive K+ channels in porcine coronary artery smooth muscle cells.
  • Y. Miyoshi, Y. Nakaya
  • Chemistry, Medicine
    Biochemical and biophysical research communications
  • 1991
ATP-sensitive K+ channels with small conductance in porcine coronary artery smooth muscle cells were highly active at physiological concentrations of Ca2+ even in the presence of physiological ATP levels, suggesting that these channels contribute to the generation of the resting membrane potential in vascular smooth Muscle cells and their modulation is important in controlling vasomotor tone.
The ATP-sensitive K+ channel
A small conductance K+ channel, that is inactivated by ATP, was recently found in the inner membrane of rat liver mitochondria, which clearly indicates that a variety of K+ channels, showing ATP-sensitivity, are widely distributed.
ATP‐sensitive K channels in heart muscle Spare channels
The results considerably widen the range of internal ATP concentrations over which one might expect activation of the ATP‐sensitive K+ current in cardiac myocytes.


Ionic Currents during Hypoxia in Voltage‐Clamped Cat Ventricular Muscle
It is concluded that the shortening of the cardiac action potential in the early stage of hypoxia results from an increase in K+outward background current.
Single channel recordings of Ca2+-activated K+ currents in rat muscle cell culture
The extracellular patch clamp technique is used to record the currents from patches of intact and isolated plasma cell membrane from rat myotubes and observe single channel currents that would give rise to Ca2+-activated K+ conductance, which is highly selective to K+ and has a conductance near 100 pS at physiological [K+].
Ca-dependent K channels with large unitary conductance in chromaffin cell membranes
Patches of membranes containing functional, Ca-dependent K channels have been isolated from chromaffin cells and it is shown that application of low Ca concentrations to the inner side of the membrane affects the properties of the channels, while Ca ions are ineffective on the outer side ofThe membrane.
Single K+ channel currents of anomalous rectification in cultured rat myotubes.
The currents through single K+ channels of the anomalous (or inward) rectifier were recorded in tissue cultured rat myotubes by using the "gigohm seal" patch clamp technique developed by Sigworth and
Receptor for ATP in the membrane of mammalian sensory neurones
ATP-activated conductance has been found in a large number of neurones isolated from various sensory ganglia of the rat and cat and the sequence of agonists is different from those previously described for purinergic receptors P1 and P2.
A possible mechanism of glycolytic impairment after adenosine triphosphate deplection in the perfused rat heart.
The block in anaerobic glycolysis can be overcome by a brief period of oxidative metabolism, apparently because the improvement in adenine nucleotide levels serves to ‘re‐prime’ the system.
Single channel potassium currents of the anomalous rectifier
The statistics of pulse-like events in the patch current were found to be consistent with the inactivation kinetics of the anomalous rectifier, and the extrapolated zero-current potential of the pulse- like events was approximately equal to that of the total anomalous K current.
Excitation-contraction coupling in heart muscle: Membrane control of development of tension
III. EXCITATION-CONTRACT/ON COUPLING PROCESSES IN THE MAMMALIAN VENTRICLE A. Structure 1. Transverse-tubular system 2. Sarcoplasmic reticulum B. Functional Implications of the Structure of the
Spontaneously active cells isolated from the sino-atrial and atrio-ventricular nodes of the rabbit heart.
It is indicated that the isolated cells maintain the typical membrane characteristics of the nodal cells and that they are suitable for electrophysiological studies of the cardiac pacemaker cell.
Nucleotide Metabolism in Cardiac Activity: II. Reactions in Systole
Relaxed mammalian hearts contain ATP as the predominant nucleotide, sometimes accompanied by smaller amounts of ADP, presumably formed during manipulation. In systole, one-tenth of the nucleotide is