Hypokalemia decreases Na(+)-K(+)-ATPase alpha 2- but not alpha 1-isoform abundance in heart, muscle, and brain

1991 ◽  
Vol 260 (5) ◽  
pp. C958-C964 ◽  
Author(s):  
K. K. Azuma ◽  
C. B. Hensley ◽  
D. S. Putnam ◽  
A. A. McDonough
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Heart Muscle ◽  
Similar Pattern ◽  
Protein Abundance ◽  
Large Decrease ◽  
Ouabain Binding ◽  
Protein Levels ◽  
K Deficiency

K+ deficiency has been linked to a loss of K+ from muscle associated with a decrease in ouabain binding and K(+)-dependent phosphatase activity. This study aimed to quantitate the Na(+)-K(+)-ATPase alpha- and beta-isoform-specific responses to hypokalemia in vivo in heart, skeletal muscle, and brain at pre- and posttranslational levels. Two-week dietary K+ restriction resulted in decreases in alpha 2-mRNA in heart and skeletal muscle to 0.60 and 0.65, and in alpha 2-protein abundance to 0.38 and 0.18 of control, respectively. The decrease in alpha 2-protein was greater than the decrease in mRNA in both tissues, suggesting translational and/or posttranslational mechanism(s) of regulation as well as pretranslational regulation in response to hypokalemia. K(+)-dependent p-nitrophenyl phosphatase (pNPPase) activity decreased in heart and skeletal muscle to 0.67 and 0.58, respectively. There were no changes in alpha 1-. or beta-mRNA or protein levels in skeletal muscle or heart. In brain, there was a similar pattern of regulation. While brain alpha 2-mRNA did not change in hypokalemia, protein levels decreased to 0.72 of control. In conclusion, hypokalemia is associated with a large decrease in expression of the alpha 2-isoform of Na(+)-K(+)-ATPase. These results support the hypothesis that in skeletal and heart muscle hypokalemia induces a decrease in Na(+)-K(+)-ATPase activity (measured as K(+)-dependent pNPPase activity) by specifically decreasing the expression of the alpha 2-isoform of Na(+)-K(+)-ATPase.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid hormone specifically regulates skeletal muscle Na(+)-K(+)-ATPase alpha 2- and beta 2-isoforms

1993 ◽  
Vol 265 (3) ◽  
pp. C680-C687 ◽  
Author(s):  
K. K. Azuma ◽  
C. B. Hensley ◽  
M. J. Tang ◽  
A. A. McDonough
Keyword(s):  
Skeletal Muscle ◽  
Thyroid Hormone ◽  
State Level ◽  
Mrna Abundance ◽  
Northern Analysis ◽  
Protein Abundance ◽  
Constant Amount ◽  
Protein Levels ◽  
Subunit Expression ◽  
Beta 2

The purpose of this study was to determine the pattern of thyroid hormone (triiodothyronine, T3) regulation of the Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase) alpha- and beta-subunit expression in skeletal muscle, which expresses alpha 1-, alpha 2-, beta 1-, and beta 2-subunits, and compare it with that seen in kidney, which expresses only alpha 1 and beta 1. Three steady states were studied: hypothyroid, euthyroid, and hyperthyroid (hypothyroids injected daily with 1 microgram T3/g body wt for 2-16 days). Protein and mRNA abundance, determined by Western and Northern analysis, were normalized to a constant amount of homogenate protein and total RNA, respectively. In skeletal muscle, there was no change in alpha 1- or beta 1-mRNA or protein levels in the transition from hypothyroid to hyperthyroid. However, alpha 2 was highly regulated; mRNA reached a new steady-state level of fivefold over hypothyroid by 8 days of T3 treatment and protein abundance increased threefold. In addition, beta 2-mRNA and protein were detected in skeletal muscle and were also highly regulated by T3; beta 2-mRNA increased nearly fourfold over hypothyroid level, and beta 2-protein abundance increased over twofold. In kidney in the transition from hypothyroid to hyperthyroid, there were coordinate 1.6-fold increases in both alpha 1- and beta 1-mRNA abundance that predicted the observed changes in alpha 1- and beta 1-protein levels and Na(+)-K(+)-ATPase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Prep1 Deficiency Induces Protection from Diabetes and Increased Insulin Sensitivity through a p160-Mediated Mechanism

2008 ◽  
Vol 28 (18) ◽  
pp. 5634-5645 ◽  
Author(s):  
Francesco Oriente ◽  
Luis Cesar Fernandez Diaz ◽  
Claudia Miele ◽  
Salvatore Iovino ◽  
Silvia Mori ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Glucose Uptake ◽  
Normal Glucose Tolerance ◽  
Glucose Disposal ◽  
Protein Levels ◽  
Normal Glucose ◽  
Enhanced Expression ◽  
The Stability

ABSTRACT We have examined glucose homeostasis in mice hypomorphic for the homeotic transcription factor gene Prep1. Prep1-hypomorphic (Prep1 i / i ) mice exhibit an absolute reduction in circulating insulin levels but normal glucose tolerance. In addition, these mice exhibit protection from streptozotocin-induced diabetes and enhanced insulin sensitivity with improved glucose uptake and insulin-dependent glucose disposal by skeletal muscle. This muscle phenotype does not depend on reduced expression of the known Prep1 transcription partner, Pbx1. Instead, in Prep1 i / i muscle, we find normal Pbx1 but reduced levels of the recently identified novel Prep1 interactor p160. Consistent with this reduction, we find a muscle-selective increase in mRNA and protein levels of PGC-1α, accompanied by enhanced expression of the GLUT4 transporter, responsible for insulin-stimulated glucose uptake in muscle. Indeed, using L6 skeletal muscle cells, we induced the opposite effects by overexpressing Prep1 or p160, but not Pbx1. In vivo skeletal muscle delivery of p160 cDNA in Prep1 i / i mice also reverses the molecular phenotype. Finally, we show that Prep1 controls the stability of the p160 protein. We conclude that Prep1 controls insulin sensitivity through the p160-GLUT4 pathway.

scholarly journals Large G protein α-subunit XLαs limits clathrin-mediated endocytosis and regulates tissue iron levels in vivo

2017 ◽  
Vol 114 (45) ◽  
pp. E9559-E9568 ◽  
Author(s):  
Qing He ◽  
Richard Bouley ◽  
Zun Liu ◽  
Marc N. Wein ◽  
Yan Zhu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
G Protein ◽  
Critical Role ◽  
Hek293 Cells ◽  
Activity Levels ◽  
Α Subunit ◽  
Proteomic Screen ◽  
Protein Levels ◽  
G Protein Α Subunit

Alterations in the activity/levels of the extralarge G protein α-subunit (XLαs) are implicated in various human disorders, such as perinatal growth retardation. Encoded by GNAS, XLαs is partly identical to the α-subunit of the stimulatory G protein (Gsα), but the cellular actions of XLαs remain poorly defined. Following an initial proteomic screen, we identified sorting nexin-9 (SNX9) and dynamins, key components of clathrin-mediated endocytosis, as binding partners of XLαs. Overexpression of XLαs in HEK293 cells inhibited internalization of transferrin, a process that depends on clathrin-mediated endocytosis, while its ablation by CRISPR/Cas9 in an osteocyte-like cell line (Ocy454) enhanced it. Similarly, primary cardiomyocytes derived from XLαs knockout (XLKO) pups showed enhanced transferrin internalization. Early postnatal XLKO mice showed a significantly higher degree of cardiac iron uptake than wild-type littermates following iron dextran injection. In XLKO neonates, iron and ferritin levels were elevated in heart and skeletal muscle, where XLαs is normally expressed abundantly. XLKO heart and skeletal muscle, as well as XLKO Ocy454 cells, showed elevated SNX9 protein levels, and siRNA-mediated knockdown of SNX9 in XLKO Ocy454 cells prevented enhanced transferrin internalization. In transfected cells, XLαs also inhibited internalization of the parathyroid hormone and type 2 vasopressin receptors. Internalization of transferrin and these G protein-coupled receptors was also inhibited in cells expressing an XLαs mutant missing the Gα portion, but not Gsα or an N-terminally truncated XLαs mutant unable to interact with SNX9 or dynamin. Thus, XLαs restricts clathrin-mediated endocytosis and plays a critical role in iron/transferrin uptake in vivo.

Effects of IGF-I infusion on growth and muscle Na(+)-K+ pump concentration in K(+)-deficient rats

1993 ◽  
Vol 264 (5) ◽  
pp. E810-E815 ◽  
Author(s):  
I. Dorup ◽  
A. Flyvbjerg
Keyword(s):  
Binding Site ◽  
Control Group ◽  
Recombinant Human Insulin ◽  
Ouabain Binding ◽  
Muscle Weight ◽  
Igf I ◽  
Organ Specific ◽  
K Deficiency ◽  
Edl Muscle

K(+)-deficient rats and control rats were infused for 14 days with vehicle: acetic acid (AcA) or recombinant human insulin-like growth factor-I (IGF-I, 240 micrograms/day) by osmotic minipumps. IGF-I treatment of K(+)-deficient rats did not result in overall growth of carcass or muscles but in marked selective growth of adrenals (+42%) and spleen (+66%). In control rats, IGF-I induced increased body and muscle weight, tibia length, and thymus weight. K+ deficiency was associated with reduced serum IGF-I but unchanged thyroid status. IGF-I treatment of the K(+)-deficient rats restored serum IGF-I and decreased total 3,5,3'-triiodothyronine. In AcA-treated K(+)-deficient rats [3H]ouabain binding site concentration decreased by 63 and 43% in soleus and extensor digitorum longus (EDL) muscle, respectively, compared with the AcA-treated controls. IGF-I had no effect on the [3H]ouabain binding site concentration in the control group, but in K(+)-deficient rats a significant lowering of 26% was observed in EDL. K+ deficiency causes relative organ-specific resistance to the growth-promoting effects of IGF-I, comparable to the effects seen in protein-restricted rats. Reduced circulating IGF-I is not the only cause of the downregulation of Na(+)-K+ pumps in K+ deficiency, and IGF-I treatment of control animals in vivo has no stimulatory effect on the synthesis of Na(+)-K+ pumps.

Evidence for Increased In Vivo Na+/K+-Atpase Activity in Skeletal Muscle of Spontaneously Hypertensive Rats

1990 ◽  
Vol 78 (s22) ◽  
pp. 8P-8P ◽  
Author(s):  
PD Syme ◽  
RM Dixon ◽  
JK Aronson ◽  
DG Grahame-Smith ◽  
GK Radda
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive

scholarly journals Effects of potassium deficiency on growth and protein synthesis in skeletal muscle and the heart of rats

1989 ◽  
Vol 62 (2) ◽  
pp. 269-284 ◽  
Author(s):  
Inge Dôrup ◽  
Torben Clausen
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Control Level ◽  
Inhibitory Effect ◽  
Potassium Deficiency ◽  
Skeletal Muscle Protein ◽  
K Deficiency

The effects of potassium deficiency on growth, K content and protein synthesis have been compared in 4–13-week-old rats. When maintained on K-deficient fodder (1 mmol/kg) rats ceased to grow within a few days, and the incorporation of [3H]leucine into skeletal muscle protein in vivo was reduced by 28–38%. Pair-feeding experiments showed that this inhibition was not due to reduced energy intake. Following 14 d on K-deficient fodder, there was a further reduction (39–56 %) in the incorporation of [3H]leucine into skeletal muscle protein, whereas the incorporation into plasma, heart and liver proteins was not affected. The accumulation of the non-metabolized amino acid α-aminoisobutyric acid in the heart and skeletal muscles was not reduced. The inhibitory effect of K deficiency on 3H-labelling of muscle protein was seen following intraperitoneal (10–240 min) as well as intravenous (10 min) injection of [3H]leucine. In addition, the incorporation of [3H]phenylalanine into skeletal muscle protein was reduced in K-depleted animals. Following acute K repletion in vivo leading to complete normalization of muscle K content, the incorporation of [3H]leucine into muscle protein showed no increase within 2 h, but reached 76 and 104% of the control level within 24 and 72 h respectively. This was associated with a rapid initial weight gain, but normal body-weight was not reached until after 7 weeks of K repletion. Following 7 d on K-deficient fodder the inhibition of growth and protein synthesis was closely correlated with the K content of the fodder (1–40 mmol/kg) and significant already at modest reductions in muscle K content. In vitro experiments with soleus muscle showed a linear relationship between the incorporation of [3H]leucine into muscle protein and K content, but the sensitivity to cellular K deficiency induced in vitro was much less pronounced than that induced in vivo. Thus, in soleus and extensor digitorum longus (EDL) muscles prepared from K-deficient rats, the incorporation of [3H]leucine was reduced by 30 and 47 % respectively. This defect was completely restored by 24 h K repletion in vivo. It is concluded that in the intact organism protein synthesis and growth are very sensitive to dietary K deficiency and that this can only partly be accounted for by the reduction in cellular K content per se. The observations emphasize the need for adequate K supplies to ensure optimum utilization of food elements for protein synthesis and growth.

scholarly journals Aldosterone rapidly activates p-PKC delta and GPR30 but suppresses p-PKC epsilon protein levels in rat kidney

2019 ◽  
Vol 53 (3) ◽  
pp. 154-164 ◽  
Author(s):  
Somchit Eiam-Ong ◽  
Mookda Chaipipat ◽  
Krissanapong Manotham ◽  
Somchai Eiam-Ong
Keyword(s):  
Rat Kidney ◽  
Kidney Cortex ◽  
Protein Abundance ◽  
Protein Levels ◽  
Pkc Delta ◽  
Pkc Epsilon ◽  
Male Wistar Rats ◽  
Pkc Alpha

AbstractObjectives. Aldosterone rapidly enhances protein kinase C (PKC) alpha and beta1 proteins in the rat kidney. The G protein-coupled receptor 30 (GPR30)-mediated PKC pathway is involved in the inhibition of the potassium channel in HEK-239 cells. GPR30 mediates rapid actions of aldosterone in vitro. There are no reports available regarding the aldosterone action on other PKC isoforms and GPR30 proteins in vivo. The aim of the present study was to examine rapid actions of aldosterone on protein levels of phosphorylated PKC (p-PKC) delta, p-PKC epsilon, and GPR30 simultaneously in the rat kidney.Methods. Male Wistar rats were intraperitoneally injected with normal saline solution or aldosterone (150 µg/kg body weight). After 30 minutes, abundance and immunoreactivity of p-PKC delta, p-PKC epsilon, and GPR30 were determined by Western blot analysis and immunohisto-chemistry, respectively.Results. Aldosterone administration significantly increased the renal protein abundance of p-PKC delta by 80% (p<0.01) and decreased p-PKC epsilon protein by 50% (p<0.05). Aldosterone injection enhanced protein immunoreactivity of p-PKC delta but suppressed p-PKC epsilon protein intensity in both kidney cortex and medulla. Protein abundance of GPR30 was elevated by aldosterone treatment (p<0.05), whereas the immunoreactivity was obviously changed in the kidney cortex and inner medulla. Aldosterone translocated p-PKC delta and GPR30 proteins to the brush border membrane of proximal convoluted tubules.Conclusions. This is the first in vivo study simultaneously demonstrating that aldosterone administration rapidly elevates protein abundance of p-PKC delta and GPR30, while p-PKC epsilon protein is suppressed in rat kidney. The stimulation of p-PKC delta protein levels by aldosterone may be involved in the activation of GPR30.

scholarly journals Protein modification during biological aging: selective tyrosine nitration of the SERCA2a isoform of the sarcoplasmic reticulum Ca2+-ATPase in skeletal muscle

1999 ◽  
Vol 340 (3) ◽  
pp. 657-669 ◽  
Author(s):  
Rosa I. VINER ◽  
Deborah A. FERRINGTON ◽  
Todd D. WILLIAMS ◽  
Diana J. BIGELOW ◽  
Christian SCHÖNEICH
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Biological Aging ◽  
Tyrosine Nitration ◽  
Age Dependent ◽  
Slow Twitch Muscle ◽  
Slow Twitch ◽  
Fast Twitch

The accumulation of covalently modified proteins is an important hallmark of biological aging, but relatively few studies have addressed the detailed molecular-chemical changes and processes responsible for the modification of specific protein targets. Recently, Narayanan et al. [Narayanan, Jones, Xu and Yu (1996) Am. J. Physiol. 271, C1032-C1040] reported that the effects of aging on skeletal-muscle function are muscle-specific, with a significant age-dependent change in ATP-supported Ca2+-uptake activity for slow-twitch but not for fast-twitch muscle. Here we have characterized in detail the age-dependent functional and chemical modifications of the rat skeletal-muscle sarcoplasmic-reticulum (SR) Ca2+-ATPase isoforms SERCA1 and SERCA2a from fast-twitch and slow-twitch muscle respectively. We find a significant age-dependent loss in the Ca2+-ATPase activity (26% relative to Ca2+-ATPase content) and Ca2+-uptake rate specifically in SR isolated from predominantly slow-twitch, but not from fast-twitch, muscles. Western immunoblotting and amino acid analysis demonstrate that, selectively, the SERCA2a isoform progressively accumulates a significant amount of nitrotyrosine with age (≈ 3.5±0.7 mol/mol of SR Ca2+-ATPase). Both Ca2+-ATPase isoforms suffer an age-dependent loss of reduced cysteine which is, however, functionally insignificant. In vitro, the incubation of fast- and slow-twitch muscle SR with peroxynitrite (ONOO-) (but not NO/O2) results in the selective nitration only of the SERCA2a, suggesting that ONOO- may be the source of the nitrating agent in vivo. A correlation of the SR Ca2+-ATPase activity and covalent protein modifications in vitro and in vivo suggests that tyrosine nitration may affect the Ca2+-ATPase activity. By means of partial and complete proteolytic digestion of purified SERCA2a with trypsin or Staphylococcus aureus V8 protease, followed by Western-blot, amino acid and HPLC-electrospray-MS (ESI-MS) analysis, we localized a large part of the age-dependent tyrosine nitration to the sequence Tyr294-Tyr295 in the M4-M8 transmembrane domain of the SERCA2a, close to sites essential for Ca2+ translocation.

The biological roles of exercise-induced cytokines: IL-6, IL-8, and IL-15

2007 ◽  
Vol 32 (5) ◽  
pp. 833-839 ◽  
Author(s):  
Anders Rinnov Nielsen ◽  
Bente Klarlund Pedersen
Keyword(s):  
Skeletal Muscle ◽  
Systemic Circulation ◽  
Glucose Disposal ◽  
Acid Oxidation ◽  
Tissue Mass ◽  
Protein Levels ◽  
Exercise Induced ◽  
Net Release

Skeletal muscle fibers express several cytokines, including interleukin (IL)-6, IL-8, and IL-15. Solid evidence exists that muscular IL-6 and IL-8 are regulated by muscle contractions, at both the mRNA and the protein levels. IL-6 increases insulin-stimulated glucose disposal and fatty acid oxidation in humans in vivo. Both IL-6 and IL-8 are released from working skeletal muscle, but because IL-6 contributes to the systemic circulation only a small transient net release of IL-8 is found from working muscle, suggesting that IL-8 may exert its effects locally in the muscle. IL-15 is a recently discovered growth factor, which is highly expressed in skeletal muscle. Interestingly, although IL-15 has been demonstrated as having anabolic effects on skeletal muscle in vitro and in vivo, it seems to play a role in reducing adipose tissue mass, and a role for IL-15 in muscle–fat cross-talk has been hypothesized. In conclusion, muscle-derived cytokines appear to have important roles in metabolism, and exercise plays a role in orchestrating the interplay between cytokines and metabolism.

Extrarenal potassium adaptation: role of skeletal muscle

1986 ◽  
Vol 251 (2) ◽  
pp. F313-F318 ◽  
Author(s):  
J. D. Blachley ◽  
B. P. Crider ◽  
J. H. Johnson
Keyword(s):  
Skeletal Muscle ◽  
Binding Capacity ◽  
Lethal Dose ◽  
Plasma Potassium ◽  
Potassium Salts ◽  
Ouabain Binding ◽  
High Potassium ◽  
Potassium Adaptation

Following the ingestion of a high-potassium-content diet for only a few days, the plasma potassium of rats rises only modestly in response to a previously lethal dose of potassium salts. This acquired tolerance, termed potassium adaptation, is principally the result of increased capacity to excrete potassium into the urine. However, a substantial portion of the acute potassium dose is not immediately excreted and is apparently translocated into cells. Previous studies have failed to show an increase in the content of potassium of a variety of tissues from such animals. Using 86Rb as a potassium analogue, we have shown that the skeletal muscle of potassium-adapted rats takes up significantly greater amounts of potassium in vivo in response to an acute challenge than does that of control animals. Furthermore, the same animals exhibit greater efflux of 86Rb following the termination of the acute infusion. We have also shown that the Na+-K+-ATPase activity and ouabain-binding capacity of skeletal muscle microsomes are increased by the process of potassium adaptation. We conclude that skeletal muscle is an important participant in potassium adaptation and acts to temporarily buffer acute increases in the extracellular concentration of potassium.

Sign in / Sign up

Export Citation Format

Share Document