scholarly journals AIF4-induced inhibition of the ATPase activity, the Ca2+-transport activity and the phosphoprotein-intermediate formation of plasma-membrane and endo(sarco)plasmic-reticulum Ca2+-transport ATPases in different tissues. Evidence for a tissue-dependent functional difference

1989 ◽  
Vol 261 (2) ◽  
pp. 655-660 ◽  
Author(s):  
L Missiaen ◽  
F Wuytack ◽  
H De Smedt ◽  
F Amant ◽  
R Casteels
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Intermediate Formation ◽  
Functional Difference ◽  
Transport Activity ◽  
Fast Skeletal Muscle ◽  
Transport Atpase ◽  
Plasmic Reticulum

AIF4- inhibits the (Ca2+ + Mg2+)-ATPase activity of the plasma-membrane and the sarcoplasmic-reticulum Ca2+-transport ATPase [Missiaen, Wuytack, De Smedt, Vrolix & Casteels (1988) Biochem. J. 253, 827-833]. The aim of the present work was to investigate this inhibition further. We now report that AIF4- inhibits not only the (Ca2+ + Mg2+)-ATPase activity, but also the ATP-dependent 45Ca2+ transport, and the formation of the phosphoprotein intermediate by these pumps. Mg2+ potentiated the effect of AIF4-, whereas K+ had no such effect. The plasma-membrane Ca2+-transport ATPase from erythrocytes was 20 times less sensitive to inhibition by AIF4- as compared with the Ca2+-transport ATPase from smooth muscle. The endoplasmic-reticulum Ca2+-transport ATPase from smooth muscle was inhibited to a greater extent than the sarcoplasmic-reticulum Ca2+-transport ATPase of slow and fast skeletal muscle.

scholarly journals Inhibitory antibodies to plasmalemmal Ca2+-transporting ATPases. Their use in subcellular localization of (Ca2+ + Mg2+)-dependent ATPase activity in smooth muscle

1985 ◽  
Vol 231 (3) ◽  
pp. 737-742 ◽  
Author(s):  
J Verbist ◽  
F Wuytack ◽  
L Raeymaekers ◽  
R Casteels
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Muscle ◽  
Plasma Membrane ◽  
Atpase Activity ◽  
Membrane Fraction ◽  
Transport Atpase ◽  
Calmodulin Binding ◽  
Dependent Atpase ◽  
Inhibitory Antibodies ◽  
Stimulation Of

Antibodies directed against the purified calmodulin-binding (Ca2+ + Mg2+)-ATPase [(Ca2+ + Mg2+)-dependent ATPase] from pig erythrocytes and from smooth muscle of pig stomach (antral part) were raised in rabbits. Both the IgGs against the erythrocyte (Ca2+ + Mg2+)-ATPase and against the smooth-muscle (Ca2+ + Mg2+)-ATPase inhibited the activity of the purified calmodulin-binding (Ca2+ + Mg2+)-ATPase from smooth muscle. Up to 85% of the total (Ca2+ + Mg2+)-ATPase activity in a preparation of KCl-extracted smooth-muscle membranes was inhibited by these antibodies. The (Ca2+ + Mg2+)-ATPase activity and the Ca2+ uptake in a plasma-membrane-enriched fraction from this smooth muscle were inhibited to the same extent, whereas in an endoplasmic-reticulum-enriched membrane fraction the (Ca2+ + Mg2+)-ATPase activity was inhibited by only 25% and no effect was observed on the oxalate-stimulated Ca2+ uptake. This supports the hypothesis that, in pig stomach smooth muscle, two separate types of Ca2+-transport ATPase exist: a calmodulin-binding ATPase located in the plasma membrane and a calmodulin-independent one present in the endoplasmic reticulum. The antibodies did not affect the stimulation of the (Ca2+ + Mg2+)-ATPase activity by calmodulin.

scholarly journals Antibodies against erythrocyte Ca2+-transport ATPase specifically inhibit the calmodulin-dependent fraction of the enzyme's activity

1985 ◽  
Vol 228 (2) ◽  
pp. 479-485 ◽  
Author(s):  
K Gietzen ◽  
J Kolandt
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Oleic Acid ◽  
Atpase Activity ◽  
Binding Site ◽  
Rat Brain ◽  
Limited Proteolysis ◽  
Transport Atpase ◽  
Calmodulin Binding ◽  
Muscle Plasma Membrane

Antibodies against purified Ca2+-transport ATPase from human erythrocytes were raised in rabbits. Immunodiffusion experiments revealed that precipitating antibodies had been developed. The immunoglobulin fraction inhibited solely the calmodulin-dependent fraction of erythrocyte Ca2+-transport ATPase activity, whereas the basal (in the absence of added calmodulin) activity of the enzyme was not significantly affected by the antibodies. The antibodies produced similar doseresponse curves for the calmodulin- and the oleic acid-stimulated enzyme. However, the immunoglobulin fraction was considerably less effective in inhibiting Ca2+-transport ATPase activated by limited proteolysis. The results obtained with our antibodies are compatible with the interpretation that at least one subpopulation of the antibodies attacks the enzyme at or close to the calmodulin-binding site of the ATPase. The antibodies also inhibited the calmodulin-regulated Ca2+-transport ATPase from pig smooth-muscle plasma membrane, though with lower potency. However, the immunoglobulin fraction failed to suppress pig cardiac sarcoplasmicreticulum Ca2+-transport ATPase activity in the concentration range investigated. In addition, the activity of phosphodiesterase from rat brain, another enzyme modulated by calmodulin, was not at all affected by the immunoglobulin fraction.

scholarly journals Arterial α2-Na+ pump expression influences blood pressure: lessons from novel, genetically engineered smooth muscle-specific α2 mice

2015 ◽  
Vol 309 (5) ◽  
pp. H958-H968 ◽  
Author(s):  
Ling Chen ◽  
Hong Song ◽  
Youhua Wang ◽  
Jane C. Lee ◽  
Michael I. Kotlikoff ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Smooth Muscle ◽  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Genetically Engineered ◽  
Dominant Negative ◽  
Ang Ii ◽  
Plasmic Reticulum ◽  
Altered Blood ◽  
Transporter Expression

Arterial myocytes express α1-catalytic subunit isoform Na+ pumps (75–80% of total), which are ouabain resistant in rodents, and high ouabain affinity α2-Na+ pumps. Mice with globally reduced α2-pumps (but not α1-pumps), mice with mutant ouabain-resistant α2-pumps, and mice with a smooth muscle (SM)-specific α2-transgene (α2SM-Tg) that induces overexpression all have altered blood pressure (BP) phenotypes. We generated α2SM-DN mice with SM-specific α2 (not α1) reduction (>50%) using nonfunctional dominant negative (DN) α2. We compared α2SM-DN and α2SM-Tg mice to controls to determine how arterial SM α2-pumps affect vasoconstriction and BP. α2SM-DN mice had elevated basal mean BP (mean BP by telemetry: 117 ± 4 vs. 106 ± 1 mmHg, n = 7/7, P < 0.01) and enhanced BP responses to chronic ANG II infusion (240 ng·kg−1·min−1) and high (6%) NaCl. Several arterial Ca2+ transporters, including Na+/Ca2+ exchanger 1 (NCX1) and sarcoplasmic reticulum and plasma membrane Ca2+ pumps [sarco(endo)plasmic reticulum Ca2+-ATPase 2 (SERCA2) and plasma membrane Ca2+-ATPase 1 (PMCA1)], were also reduced (>50%). α2SM-DN mouse isolated small arteries had reduced myogenic reactivity, perhaps because of reduced Ca2+ transporter expression. In contrast, α2SM-Tg mouse aortas overexpressed α2 (>2-fold), NCX1, SERCA2, and PMCA1 (43). α2SM-Tg mice had reduced basal mean BP (104 ± 1 vs. 109 ± 2 mmHg, n = 15/9, P < 0.02) and attenuated BP responses to chronic ANG II (300–400 ng·kg−1·min−1) with or without 2% NaCl but normal myogenic reactivity. NCX1 expression was inversely related to basal BP in SM-α2 engineered mice but was directly related in SM-NCX1 engineered mice. NCX1, which usually mediates arterial Ca2+ entry, and α2-Na+ pumps colocalize at plasma membrane-sarcoplasmic reticulum junctions and functionally couple via the local Na+ gradient to help regulate cell Ca2+. Altered Ca2+ transporter expression in SM-α2 engineered mice apparently compensates to minimize Ca2+ overload (α2SM-DN) or depletion (α2SM-Tg) and attenuate BP changes. In contrast, Ca2+ transporter upregulation, observed in many rodent hypertension models, should enhance Ca2+ entry and signaling and contribute significantly to BP elevation.

Coordination of cardiac myofibrillar and sarcotubular activities in rats exercised by swimming

1984 ◽  
Vol 247 (6) ◽  
pp. H909-H915 ◽  
Author(s):  
E. D. Pagani ◽  
R. J. Solaro
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Functional Activity ◽  
Storage Capacity ◽  
Training Effect ◽  
Myofibrillar Atpase ◽  
Transport Activity ◽  
Cross Bridge ◽  
Myofibrillar Atpase Activity ◽  
The Mean

We measured the functional activity of both myofibrils and fragmented sarcoplasmic reticulum (FSR) in microsomal fractions and homogenates of hearts of sedentary rats and rats exercised by swimming 75 min twice daily for 8 wk. Ca2+ transport was measured under conditions that restricted uptake of Ca2+ to the SR vesicles in the homogenates or microsomal fractions. There was a significant increase in myosin Ca2+-ATPase activity of myofibrils prepared from hearts of swimmers, indicating that a “training effect” had occurred. The mean rate of Ca2+ transport and mean storage capacity were the same for SR vesicles in the homogenates and microsomal fractions from hearts of controls and swimmers. At the same free Ca2+ concentration, the velocity of Ca2+ transport by FSR in homogenate preparations was inversely related to the myofibrillar ATPase activity in a series of preparations from hearts of swimmers, but there was little correlation between the same activities measured in preparations from a series of sedentary rats. Our results suggest that the increase in the rate of relaxation of hearts from exercised rats is not due to an increase in the rate of Ca2+ transport by the SR but may be due to other factors, which include an increase in the rate of cross-bridge cycling or an alteration in the relation and coordination between cross-bridge cycling and SR Ca2+ transport activity.

Exercise prevents diabetes-induced impairment in superficial buffer barrier in porcine coronary smooth muscle

2004 ◽  
Vol 96 (3) ◽  
pp. 1069-1079 ◽  
Author(s):  
C. A. Witczak ◽  
M. Sturek
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Diabetic Dyslipidemia ◽  
Coronary Smooth Muscle ◽  
Treatment Groups ◽  
Analysis Techniques ◽  
Intracellular Ca

In healthy coronary smooth muscle cells, the superficial sarcoplasmic reticulum (SR) buffers rise in intracellular Ca2+ levels. In diabetic dyslipidemia, basal Ca2+ levels are increased, yet Ca2+ influx is decreased and SR Ca2+ uptake is increased. Exercise prevents diabetic dyslipidemia-induced increases in basal Ca2+ levels and decreases in Ca2+ influx. We tested the hypothesis that diabetic dyslipidemia impairs Ca2+ extrusion via a decrease in superficial SR and that exercise will prevent these losses. Male Yucatan swine were maintained in four treatment groups: control, hyperlipidemic, diabetic dyslipidemic, and diabetic dyslipidemic plus aerobically exercise trained. Intracellular Ca2+ levels were measured during depolarization-induced Ca2+ influx and caffeine-induced SR Ca2+ release. Na+/Ca2+ exchanger and plasmalemmal Ca2+-ATPase activity were assessed by inhibition with low extracellular Na+ and 5,6-carboxyeosin, respectively. Superficial SR was quantified using the internal membrane dye 3,3′-dihexyloxacarbocyanine iodide (DiOC6) and novel analysis techniques. We found that, in diabetic dyslipidemia, Ca2+ extrusion was impaired and superficial SR was decreased. Exercise prevented the diabetic dyslipidemia-induced decrease in superficial SR and restored plasmalemmal Ca2+ extrusion. On the basis of these results, we conclude exercise attenuates the diabetic dyslipidemia-induced impairment in intracellular Ca2+ regulation.

scholarly journals Adaptations in human muscle sarcoplasmic reticulum to prolonged submaximal training

2003 ◽  
Vol 94 (5) ◽  
pp. 2034-2042 ◽  
Author(s):  
H. J. Green ◽  
C. S. Ballantyne ◽  
J. D. MacDougall ◽  
M. A. Tarnopolsky ◽  
J. D. Schertzer
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Vastus Lateralis ◽  
Training Session ◽  
Maximal Activity ◽  
Hill Coefficient ◽  
Protein Levels ◽  
Plasmic Reticulum ◽  
Cycle Training ◽  
The Hill

In this study, we employed single-leg submaximal cycle training, conducted over a 10-wk period, to investigate adaptations in sarcoplasmic reticulum (SR) Ca2+-regulatory proteins and processes of the vastus lateralis. During the final weeks, the untrained volunteers (age 21.4 ± 0.3 yr; means ± SE, n = 10) were exercising 5 times/wk and for 60 min/session. Analyses were performed on tissue extracted by needle biopsy ∼4 days after the last training session. Compared with the control leg, the trained leg displayed a 19% reduction ( P < 0.05) in homogenate maximal Ca2+-ATPase activity (192 ± 11 vs. 156 ± 18 μmol · g protein−1 · min−1), a 4.3% increase ( P < 0.05) in pCa50, defined as the Ca2+ concentration at half-maximal activity (6.01 ± 0.05 vs. 6.26 ± 0.07), and no change in the Hill coefficient (1.75 ± 0.15 vs. 1.76 ± 0.21). Western blot analysis using monoclonal antibodies (7E6 and A52) revealed a 13% lower ( P < 0.05) sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) 1 in trained vs. control in the absence of differences in SERCA2a. Training also resulted in an 18% lower ( P < 0.05) SR Ca2+ uptake and a 26% lower ( P < 0.05) Ca2+ release. It is concluded that a downregulation in SR Ca2+ cycling in vastus lateralis occurs with aerobic-based training, which at least in the case of Ca2+ uptake can be explained by reduction in Ca2+-ATPase activity and SERCA1 protein levels.

scholarly journals CALCIUM UPTAKE, RELEASE AND Mg-ATPase ACTIVITY OF SARCOPLASMIC RETICULUM FROM ARTERIAL SMOOTH MUSCLE

1976 ◽  
Vol 40 (10) ◽  
pp. 1175-1181 ◽  
Author(s):  
KANAE YAMASHITA ◽  
KYUZO AOKI ◽  
KIYOHARU TAKIKAWA ◽  
KEN HOTTA
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Calcium Uptake ◽  
Arterial Smooth Muscle

A role for the sarcoplasmic reticulum in Ca2+ extrusion from rabbit inferior vena cava smooth muscle

1998 ◽  
Vol 274 (1) ◽  
pp. H123-H131 ◽  
Author(s):  
Mark A. Nazer ◽  
Cornelis Van Breemen
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Vena Cava ◽  
Cyclopiazonic Acid ◽  
Free Solution ◽  
Intracellular Ca ◽  
In Series

Ca2+extrusion from rabbit inferior vena cava smooth muscle was studied using ratiometric fura 2 fluorimetry. Concomitant blockade of the plasma membrane Ca2+-adenosinetriphosphatase (ATPase; PCMA), Na+-Ca2+exchanger, and sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) completely prevented the decline in intracellular Ca2+ concentration ([Ca2+]i) normally observed when Ca2+ is removed from the extracellular space (ECS) after stimulated Ca2+ influx. Blockade of the Na+-Ca2+exchanger by removal of external Na+ reduced the rate of [Ca2+]idecline by 47%. Blockade of SERCA with cyclopiazonic acid reduced it by 23%, and this was not additive to the effects of Na+ removal. Exposure to nominally Ca2+-free solution prevented the sarcoplasmic reticulum (SR) from reloading only if the Na+-Ca2+exchanger was operational. Our results can be explained by an SR contribution to Ca2+ extrusion in which SERCA is arranged in series with Na+-Ca2+exchange.

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