Modeling removal of accumulated potassium from T-tubules by inward rectifier potassium channels

Abstract

Abstract-The membrane models of (Cannon et al. [l] and Alberink et al. [2] for mammaliain skeletal muscle fibers are based upon Hodgkin-Huxley descriptions of sodium, potassium delayed rectifier and leak conductance's and the capacitive current taking into account fast inactivation of sodium channels. Now inward rectifier and chloride ion currents, sodiumpotassium oump and slow inactivation of sodium channels have been inserted. The behavior of the model with respect to resting membrane potential and action potential firing does not differ remarkably from 121. The model has been used to study the removal of potassium from the T-tubular space. The inward rectifier current significantly contributes to the restoration of the normal potassium concentration after prolonged action potential firing. This may be an important mechanism to avoid muscle fatigue.

Palladium-Mediated Synthesis of a Near-Infrared Fluorescent K+ Sensor

“…During normal physical activity, the concentration of extracellular K + surrounding human muscle nearly triples, rising from 3.5 mM to 10 mM 2,3 . This substantial change in extracellular K + is predicted to be even greater in the transverse tubules 7–9 , though current methods do not allow for accurate measurements in these microscopic invaginations. Regulated K + efflux is also essential for the developing pancreas, kidney, and vestibular and cochlear endolymphs 5,6,10 .…”

“…Neuronal and muscle excitability, cardiac rhythmicity, vasodilation, insulin secretion, and renal function all require the spatiotemporal release of potassium (K + ) ions from cells and tissues. − During normal physical activity, the concentration of extracellular K + surrounding human muscle nearly triples, rising from 3.5 to 10 mM. , This substantial change in extracellular K + is predicted to be even greater in the transverse tubules, − though current methods do not allow for accurate measurements in these microscopic invaginations. Regulated K + efflux is also essential for the developing pancreas, kidney, and vestibular and cochlear endolymphs. ,, Accordingly, dysregulated exit of cellular K + from tissues has been associated with a multitude disease states from epilepsy, migraine auras, hypokalemic periodic paralysis, and cardiac arrhythmias to neonatal diabetes, hyperkalemia, and congenital deafness .…”