Skeletal muscle and small-conductance calcium-activated potassium channels

Comparison of gene expression of 2-mo denervated, 2-mo stimulated-denervated, and control rat skeletal muscles

“…The threefold upregulation of mRNA and sixfold upregulation of protein expression of SK3 potassium channel in rat EDL muscles after denervation are in good agreement with the data of Pribnow et al (77). Accumulation of high levels of SK3 mRNA and protein expression starts at 2-3 days (77) and, according to the present study, continues for at least 2 mo after denervation.…”

“…SK3 appears to be involved in the hyperexcitability (spontaneous fibrillatory activity) and hyperpolarization observed in denervated muscles. In addition to the presence in denervated muscles, SK3 channels are present in most neurons and in several nonexcitable cell types (77). Our data indicate that some of the muscle satellite cells also express SK3 on their plasma membrane.…”

Cardiac Potassium Channel Subtypes: New Roles in Repolarization and Arrhythmia

“…Therefore, apamin has been considered a fingerprint or state-of-the-art inhibitor of K Ca 2.x channels. Whereas in noncardiac tissue such as neurons, skeletal muscle, hepatocytes, and T lymphocytes, apamin is used broadly as a tool to address the physiological roles of K Ca 2.x channels, the experiences from using the large apamin molecule as a tool compound on cardiac tissue are less convincing (28,46,101,191,354,396). A number of alternatives to apamin exist, including peptide toxins such as scorpion toxins scyllatoxin and tamapin (406,465), and small organic molecules such as tubocurarine, UCL1684, or N-(pyridin-2-yl)-4-(pyridin-2-yl)thiazol-2-amine (138,248,366,465).…”

Design and Characterization of a Highly Selective Peptide Inhibitor of the Small Conductance Calcium-activated K+Channel, SkCa2

“…In the liver, they are believed to play a role in metabolic stress responses (6), and in human Jurkat T cells, they promote calcium entry in response to a mitogenic stimulus (7). SK Ca channels have also been implicated in fasciculations in denervated skeletal muscle (8) and in myotonic dystrophy (9). SK Ca channels, products of three phylogenetically related genes SKCa1-3, are found in a variety of tissues including the nervous system (10), liver (11), skeletal and smooth muscle (8,12), adrenal medulla (13), and lymphoid tissues (14,15).…”

“…SK Ca channels have also been implicated in fasciculations in denervated skeletal muscle (8) and in myotonic dystrophy (9). SK Ca channels, products of three phylogenetically related genes SKCa1-3, are found in a variety of tissues including the nervous system (10), liver (11), skeletal and smooth muscle (8,12), adrenal medulla (13), and lymphoid tissues (14,15). In the brain (16), the precise functional role of each channel in specific neuronal pathways has been difficult to elucidate because of the absence of selective blockers.…”