Evidence for the presence of the stearyl-CoA desaturase system in the sarcoplasmic reticulum of rabbit slow muscle (original) (raw)
Related papers
Variation in the lipid composition of rabbit muscle sarcoplasmic reticulum membrane with muscle type
Journal of Biological Chemistry
The compositions of sarcoplasmic reticulum (SR) membranes from rabbit caudofemoralis, tibialus, and soleus muscles (fast, mixed, and slow twitch, respectively) were analyzed. Compared to caudofemoralis (fast twitch) SR, soleus (slow twitch) SR contained a significantly greater percentage of cholesterol, phosphatidylinositol, and sphingomyelin and a lesser percentage of phosphatidylcholine. Correlations between properties reported for the SR isolated from different muscle types and our analyses of the compositions are discussed. We suggest that the greater cholesterol content and the greater sphingomyelin to phosphatidylcholine ratio present in soleus SR contribute to decreased bilayer fluidity and, hence, decreased ea"+-ATPase activity.
Comparison of isolated sarcoplasmic reticulum from bovine and rabbit muscle
Meat Science - MEAT SCI, 1977
Comparison of the ultrastructure of purified bovine sarcoplasmic reticulum (SR) vesicles isolated from bovine sternomandibularis muscle before and following cold shortening indicates that the decreased Ca 2 ÷-accumulating ability and increased release of Ca" ÷ in cold shortened muscle are not associated with any apparent structural alterations. Sodium dodecyl sulphate (SDS)-gel profiles revealed that the major constituent in both bovine and rabbit SR was Ca'-÷-activated ATPase with a molecular weight of 100,000-105,000. Both SR preparations also showed a proteolipid band at a molecular weight of approximately 10,000. Purified rabbit SR contained three protein components with molecular weights of 75,000, 60,000 and 53,000, whereas bovine SR exhibited a series of five components with molecular weights 0./'80,000, 66,000, 63,000, 50,000 and 45,000. Although the functions of these isolated proteins were not determined, it is assumed that at least some of them bind Ca" + ions in the SR. 1NTRODUCTI ON The sarcoplasmic reticulum (SR) consists of a membranous network, which forms a separate enclosed compartment within muscle and surrounds each myofibril like a fenestrated water jacket. Near the A-I band junction, the SR is intersected by the transverse tubule (T-tubule) system. These two membrane systems control the intracellular distribution of Ca 2 ÷, and thus are responsible for muscle contraction and relaxation (Huxley, 1972) and the related phenomenona of rigor mortis (Nauss & Davies, 1966), thaw rigor and cold shortening (Marsh, 1966).
Histochemistry, 1979
Activities of malate dehydrogenase (MDH), 3-hydroxyacyl-CoA dehydrogenase (HAD) and fructose-l,6-diphosphatase (FDPase) were determined in single fibres dissected from freeze-dried rabbit psoas and soleus muscles. Slow-twitch fibres as determined by qualitative ATPase reaction represent a rather uniform population with regard to HAD and MDH activities. In these fibres the two enzymes are in constant proportions. FDPase is found at extremely low activities in slow-twitch fibres and because of its relatively high activity in fast-twitch fibres of soleus and psoas muscle it might be used as a marker enzyme. Fast-twitch fibres in psoas muscle represent a heterogeneous population with regard to activities of MDH as well as of HAD. The two enzyme activities are not proportional in fasttwitch psoas fibres. These findings suggest the existence of metabolic subpopulations of fast-twitch fibres having a wide range of aerobic oxidative capacities and having differences in their capacity to oxidizing fatty acids.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1993
The fatty acid composition of membrane lipids from sarcolemma and sarcoplasmic reticulum isolated from biceps and gastrocnemius muscle has been compared in normal (wildtype, +/adr rot° or +/+ ) and affected (adrmt°/adr rot°) myotonic mice. The adr rot° mouse exhibits an arrested development of the righting response, and arose spontaneously from the SWR/J strain. These mice exhibit classical myotonia similar to the human disease, Becker's myotonia [1]. Significant alterations, characterized by a decrease in the saturated fatty acid, palmitic acid (16 : 0), and the polyunsaturated fatty acid, arachidonic acid (20:4), and an increase in stearic (18:0) and linoleic (18:2) acids, were observed between sarcolemma and sarcoplasmic reticulum from normal and affected mice. These changes in fatty acid composition of muscle membrane from ADR mice may be adequate to cause an alteration in membrane fluidity and affect the function of ion channels. The fatty acid composition of erythrocytes ghosts was also examined, as a potential marker for alterations in muscle membranes. In erythrocyte ghosts isolated from affected mice, the only alteration observed was a decrease in the proportion of oleic acid (18 : 1), an effect completely different from those observed in muscle membranes. Therefore, erythrocyte ghosts do not serve as an adequate indicator of changes in fatty acid composition of muscle membranes in this model of myotonia.
The Journal of Membrane Biology, 1987
Four monoclonal antibodies against the calcium ATPase in sarcoplasmic reticulum (SR) of rabbit fast-twitch skeletal muscle were characterized using SDS-PAGE, Western blots and immunofluorescence. The ultrastructural distribution of the antigens was determined using post-embedding immunolabeling. The antibodies recognized the calcium ATPase in the SR but not in transverse (T-) tubule or plasma membranes. The antibody, D12, had the same binding affinity for the calcium ATPase from fast-twitch (rabbit sternomastoid) and slow-twitch (rabbit soleus) fibers and the affinity fell by 30% after fixation for electron microscopy in both types of muscle fiber. Ultrastructural studies revealed that the density of D12 antibody binding to the terminal cisternae membrane of extensor digitorum Iongus (edl) and sternomastoid fibers was on average seven times greater than in the slow-twitch soleus and semimembranosus fibers. Since the affinity of the ATPase for the antibody was the same in SR from fast-and slow-twitch muscles, the concentration of calcium ATPase in the terminal cisternae membrane of fast-twitch fibers was seven times greater than in slow-twitch fibers. This conclusion was supported by the fact that the concentration of calcium ATPase in light SR membranes was six times greater in SR from fast-twitch fibers than in SR from slow-twitch fibers. The results provide strong evidence that the different calcium accumulation rates in mammalian fast-and slow-twitch muscles are due to different concentrations of calcium ATPase molecules in the SR membrane.
Acta Physiologica Scandinavica, 1995
Calcium release activity of sarcoplasmic reticulum and enzyme-histochemical properties were investigated in extensor digitorum longus (e.d.1.) and soleus muscles in young (4 months) and old (24 months) male rats. With age, the caffeine threshold concentration for calcium release from the sarcoplasmic reticulum of soleus skinned muscle fibres showed only minor modifications. On the other hand, in e.d.1. skinned muscle fibres, the caffeine threshold concentration decreased significantly (P < 0.05). T h e histochemical fibre type composition changed with age both in soleus and in e.d.1. muscles, showing a common transformation toward a more oxidative histochemical profile. In fact, in aged soleus, a significant (P < 0.05) increase was observed of type 1 fibres to represent almost the totality of the muscle fibres (more than 989/,), while types 2C and 2A were reduced in proportion. In aged e.d.1. the percentage of type 1 (P < 0.05), 2A and 2X (a recently identified fourth component of the fast-twitch muscle types) fibres increased, with a reduction of type 2B (P < 0.01) fibres. T h e present results suggest that the changes in contractile properties of aged muscles may be related to the changes not only in fibre composition but also in the mechanism of calcium release from sarcoplasmic reticulum.
Characterization of sarcoplasmic reticulum in skinned muscle cultures
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1989
The plasma membranes of chick or rat skeletal muscles, grown in cell culture, were made permeable with saponin in a solution lacking calcium. The edls were then supplied with a medium resembling the cytosul and the ATP-dependent Ca 2+ sequeslratlon was performed. Based on the low concentration of free Ca 2+ in the medium (below 5 ~M), the presence of mitochendrial iullibitors and the effect of drugs that interfere with sareoplasmie reficulum (SR) function, we assume that the measm'ed Ca z+ accumulation expresses SR function on the saponin-treated myotuhes. The development of the SR in muscle cultures is augmented as myogenesis proceeds and depends on its occurrence. Whereas creatine kinase activity is elevated immediately following cell fusion, there is a delay of at least 1 day between myoblast fusion and the increase in Ca 2+ accumulation in the SR. Thyroxine or triiodothyronine caused an inhibition of Ca z+ accumulation in rat or chick muscle cultures. This inhibition could explain some of the muscle abnormalities caused by excess of thyroid hormones. A comparison was made between a white-type (fast) and heterogeneous muscle, differentiated in cell culture. There was no significant difference in SR function, indicating the important role of innorvation in specifying the properties of muscle fiber types.
Carbonic anhydrase in the sarcoplasmic reticulum of rabbit skeletal muscle
The Journal of Physiology, 1986
Sarcoplasmic reticulum vesicles and mitochondria were prepared from red and white skeletal muscles of the rabbit. The preparations were characterized in terms of their specific activities of citrate synthase, basal (Mg2+‐dependent) and Ca2+‐dependent ATPase (the latter two in the presence of NaN3 and ouabain), and their specific carbonic anhydrase activities were determined. Skeletal muscle mitochondria had high specific activities of citrate synthase (700‐1200 mu. mg protein‐1) and low carbonic anhydrase activities (0.1‐0.4 u. ml mg protein‐1). The latter are likely to be due to a contamination of the preparations with sarcoplasmic reticulum (s.r.) Preparations of s.r. vesicles showed negligible activities of citrate synthase and the expected differing patterns of basal and Ca2+‐dependent ATPase in red and white muscles. Specific carbonic anhydrase activities in s.r. from both muscle types were high (2‐4 u. ml mg protein‐1). The highest carbonic anhydrase activity, 11 u. ml mg prot...
PLoS ONE, 2013
The main purpose of this study was to directly quantify the relative contribution of Ca 2+ cycling to resting metabolic rate in mouse fast (extensor digitorum longus, EDL) and slow (soleus) twitch skeletal muscle. Resting oxygen consumption of isolated muscles (VO 2 , µL/g wet weight/s) measured polarographically at 30°C was ~20% higher (P<0.05) in soleus (0.326 ± 0.022) than in EDL (0.261 ± 0.020). In order to quantify the specific contribution of Ca 2+ cycling to resting metabolic rate, the concentration of MgCl 2 in the bath was increased to 10 mM to block Ca 2+ release through the ryanodine receptor, thus eliminating a major source of Ca 2+ leak from the sarcoplasmic reticulum (SR), and thereby indirectly inhibiting the activity of the sarco(endo) plasmic reticulum Ca 2+ -ATPases (SERCAs). The relative (%) reduction in muscle VO 2 in response to 10 mM MgCl 2 was similar between soleus (48.0±3.7) and EDL (42.4±3.2). Using a different approach, we attempted to directly inhibit SERCA ATPase activity in stretched EDL and soleus muscles (1.42x optimum length) using the specific SERCA inhibitor cyclopiazonic acid (CPA, up to 160 µM), but were unsuccessful in removing the energetic cost of Ca 2+ cycling in resting isolated muscles. The results of the MgCl 2 experiments indicate that ATP consumption by SERCAs is responsible for 40-50% of resting metabolic rate in both mouse fast-and slow-twitch muscles at 30°C, or 12-15% of whole body resting VO 2 . Thus, SERCA pumps in skeletal muscle could represent an important control point for energy balance regulation and a potential target for metabolic alterations to oppose obesity.