Influence of acidosis on AMP deaminase activity in contracting fast-twitch muscle

1985 ◽  
Vol 248 (1) ◽  
pp. C43-C50 ◽  
Author(s):  
G. A. Dudley ◽  
R. L. Terjung
Keyword(s):  
Time Course ◽  
Fiber Type ◽  
Muscle Blood Flow ◽  
Iodoacetic Acid ◽  
Substrate Effect ◽  
Fiber Types ◽  
Amp Deaminase ◽  
Fast Twitch Muscle ◽  
Fast Twitch

The rate of AMP deamination to IMP and NH4, by the action of AMP deaminase, is increased in vitro by acidosis and elevations in [AMP] and [ADP]. We evaluated the influence of acidosis on the activity of AMP deaminase in contracting muscle (5 Hz) by relating the time course of IMP and NH4 production to lactate-induced acidosis in low-oxidative, fast-twitch white (FTW) and high-oxidative, fast-twitch red (FTR) muscle of the rat. Cellular acidosis was modified by controlling lactic acid accumulation by regulating muscle blood flow and using trained animals. A significant activation of AMP deaminase occurred in both muscle types, but only at times when the estimated pH was 6.6 and below (lactate content 20 mu mol/g and above). Cellular acidosis, however, is not absolutely essential, since iodoacetic acid-blocked muscle lost 85-90% of its ATP to IMP during contractions. Thus cellular acidosis seems to be an important, but not the sole, factor activating AMP deaminase during contractions. Further, the influence of acidosis is probably different between fiber types, since the estimated free AMP and ADP contents, calculated from the creatine kinase and myokinase reactions, were different in the two fiber types. Most of the activation of AMP deaminase in FTR muscle could be attributed to a substrate effect of the increased free AMP content. In contrast, most of the activation of AMP deaminase in the FTW muscle was due to factors other than a substrate effect. These results suggest that cellular acidosis during intense contraction conditions is a major factor activating AMP deaminase, especially in the low-oxidative FTW muscle fiber type.

scholarly journals lncRNA-Six1 Is a Target of miR-1611 that Functions as a ceRNA to Regulate Six1 Protein Expression and Fiber Type Switching in Chicken Myogenesis

Cells ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 243 ◽  
Author(s):  
Manting Ma ◽  
Bolin Cai ◽  
Liang Jiang ◽  
Bahareldin Ali Abdalla ◽  
Zhenhui Li ◽  
...  
Keyword(s):  
Fiber Type ◽  
Muscle Fibers ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Proliferation And Differentiation ◽  
Slow Twitch Muscle ◽  
Fast Twitch Muscle ◽  
Slow Twitch ◽  
Slow Twitch Fibers ◽  
Fast Twitch

Emerging studies indicate important roles for non-coding RNAs (ncRNAs) as essential regulators in myogenesis, but relatively less is known about their function. In our previous study, we found that lncRNA-Six1 can regulate Six1 in cis to participate in myogenesis. Here, we studied a microRNA (miRNA) that is specifically expressed in chickens (miR-1611). Interestingly, miR-1611 was found to contain potential binding sites for both lncRNA-Six1 and Six1, and it can interact with lncRNA-Six1 to regulate Six1 expression. Overexpression of miR-1611 represses the proliferation and differentiation of myoblasts. Moreover, miR-1611 is highly expressed in slow-twitch fibers, and it drives the transformation of fast-twitch muscle fibers to slow-twitch muscle fibers. Together, these data demonstrate that miR-1611 can mediate the regulation of Six1 by lncRNA-Six1, thereby affecting proliferation and differentiation of myoblasts and transformation of muscle fiber types.

scholarly journals Deep muscle-proteomic analysis of freeze-dried human muscle biopsies reveals fiber type-specific adaptations to exercise training

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
A. S. Deshmukh ◽  
D. E. Steenberg ◽  
M. Hostrup ◽  
J. B. Birk ◽  
J. K. Larsen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Exercise Training ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Human Muscle ◽  
Fiber Types ◽  
Freeze Dried ◽  
Fast Twitch Muscle ◽  
Fast Twitch ◽  
Muscle Biopsies

AbstractSkeletal muscle conveys several of the health-promoting effects of exercise; yet the underlying mechanisms are not fully elucidated. Studying skeletal muscle is challenging due to its different fiber types and the presence of non-muscle cells. This can be circumvented by isolation of single muscle fibers. Here, we develop a workflow enabling proteomics analysis of pools of isolated muscle fibers from freeze-dried human muscle biopsies. We identify more than 4000 proteins in slow- and fast-twitch muscle fibers. Exercise training alters expression of 237 and 172 proteins in slow- and fast-twitch muscle fibers, respectively. Interestingly, expression levels of secreted proteins and proteins involved in transcription, mitochondrial metabolism, Ca2+ signaling, and fat and glucose metabolism adapts to training in a fiber type-specific manner. Our data provide a resource to elucidate molecular mechanisms underlying muscle function and health, and our workflow allows fiber type-specific proteomic analyses of snap-frozen non-embedded human muscle biopsies.

AMP deaminase binding in contracting rat skeletal muscle

1992 ◽  
Vol 263 (2) ◽  
pp. C287-C293 ◽  
Author(s):  
K. W. Rundell ◽  
P. C. Tullson ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Iodoacetic Acid ◽  
Amp Deaminase ◽  
Energy Demands ◽  
Slow Twitch Muscle ◽  
Fast Twitch ◽  
Resting Muscle

AMP deaminase, which hydrolyses AMP to inosine 5'-monophosphate (IMP) and NH3 at high rates during excessive energy demands in skeletal muscle, is activated when bound to myosin in vitro. We evaluated AMP deaminase binding in vivo during muscle contractions to assess whether binding 1) is inherent to deamination and found only with high rates of IMP production or simply coincident with the contractile process and 2) requires cellular acidosis. AMP deaminase activity (mumol.min-1.g-1) was measured in the supernatant (free) and 10(4)-g pellet (bound) homogenate fractions of muscle of anesthetized rats after in situ contractions to determine the percent bound. In resting muscle, nearly all (approximately 90%) AMP deaminase is free (cytosolic). During contractions when energy balance was well maintained, binding did not significantly differ from resting values. However, during intense contraction conditions that lead to increased IMP concentration, binding increased to approximately 60% (P less than 0.001) in fast-twitch and approximately 50% in slow-twitch muscle. Binding increased in an apparent first-order manner and preceded initiation of IMP formation. Further, binding rapidly declined within 1 min after cessation of intense stimulation, even though the cell remained extremely acidotic. Extensive binding during contractions was also evident without cellular acidosis (iodoacetic acid-treated muscle). Thus the in vivo AMP deaminase-myosin complex association/dissociation is not coupled to changes in cellular acidosis. Interestingly, binding remained elevated after contractions, if energy recovery was limited by ischemia. Our results are consistent with myosin binding having a role in AMP deaminase activation and subsequent IMP formation in contracting muscle.

Creatine analogue beta-guanidinopropionic acid alters skeletal muscle AMP deaminase activity

1996 ◽  
Vol 270 (1) ◽  
pp. C76-C85 ◽  
Author(s):  
P. C. Tullson ◽  
K. W. Rundell ◽  
R. L. Sabina ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mass ◽  
Soleus Muscle ◽  
Dietary Supplementation ◽  
Amp Deaminase ◽  
Fast Twitch Muscle ◽  
Slow Twitch ◽  
Fast Twitch ◽  
White Fiber

Dietary supplementation of the creatine analogue beta-guanidinopropionic acid (beta-GPA) decreases in vitro skeletal muscle AMP deaminase (AMP-D) activity in rats. Downregulation of AMP-D activity was progressive and greater in fast-twitch muscles (70-80%) than in the slow-twitch soleus muscle (approximately 50%). The loss in AMP-D activity had little effect on inosine 5'-monophosphate accumulation in mixed-fiber muscle with intense tetanic contractions. In contrast, inosine 5'-monophosphate formation was evident earlier in fast-twitch red and white fiber sections of creatine-depleted animals during intense twitch contractions, indicating that fast-twitch muscle of beta-GPA-treated rats buffers decreases in the ATP/ADPfree ratio via deamination, even though AMP-D activity is less. Isoforms of skeletal muscle AMP-D mRNAs in mixed-fiber muscle were not altered by feeding beta-GPA for up to 9 wk. Creatine depletion did not alter total immunoreactivity; however, a redistribution of AMP-D immunoreactivity from primarily an approximately 80-kDa form toward lower apparent molecular mass species (approximately 60 and approximately 56 kDa) was observed. Posttranslational changes in AMP-D appear related to changes in activity.

Physiological, morphological, and histochemical properties of cat external anal sphincter

1988 ◽  
Vol 255 (6) ◽  
pp. G772-G778 ◽  
Author(s):  
J. Krier ◽  
T. Adams ◽  
R. A. Meyer
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Succinic Dehydrogenase ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Motor Axons ◽  
Fast Twitch Muscle ◽  
Fast Twitch ◽  
Stimulation Of

The contractile properties, morphology, and the distribution of striated muscle fiber types of the external and sphincter (EAS) were determined using axial force measurements, fiber size cross-sectional area measurements, and histochemistry. Electrical stimulation of motor axons in pudendal nerve at supramaximal intensities (10 V, 0.05 ms duration) elicited twitch contractions of EAS. The time to peak force after a single pulse ranged from 37 to 42 ms. The time for relaxation to half-maximal twitch force ranged from 20 to 29 ms. Repetitive stimulation of motor axons (0.1-3.0 Hz) produced potentiation and fatigue of single twitch contractile force, suggesting that the EAS of the cat is comprised predominantly of fast-twitch muscle fibers. Confirmation of skeletal muscle fiber types was determined by histochemistry. Frozen serial cross sections of EAS were incubated to demonstrate succinic dehydrogenase (SDH) and myosin adenosine triphosphatase after alkaline preincubation (pH 10.4). Based on these reactions, muscle fibers were classified as fast glycolytic (FG) (high ATPase, low SDH), fast oxidative-glycolytic (FOG) (high ATPase, high SDH), and slow oxidative (SO) (low ATPase, high SDH). The mean percentage +/- SE of each histochemical type was the following: FG, 73.5 +/- 3.9; FOG, 22.8 +/- 3.7; and SO, 3.7 +/- 0.6. These results indicate that the predominant fiber type for the EAS is FG. The EAS of the cat is considered a nominally fast-twitch muscle.

Diaphragm arterioles are less responsive to α1- adrenergic constriction than gastrocnemius arterioles

2002 ◽  
Vol 92 (5) ◽  
pp. 1808-1816 ◽  
Author(s):  
Aaron Aaker ◽  
M. H. Laughlin
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Gastrocnemius Muscle ◽  
Fiber Type ◽  
Muscle Blood Flow ◽  
Oxidative Capacity ◽  
Receptor Stimulation ◽  
Exercise Induced ◽  
Fast Twitch

The sympathetic nervous system has greater influence on vascular resistance in low-oxidative, fast-twitch skeletal muscle than in high-oxidative skeletal muscle (17). The purpose of this study was to test the hypothesis that arterioles isolated from low-oxidative, fast-twitch skeletal muscle [the white portion of gastrocnemius (WG)] possess greater responsiveness to adrenergic constriction than arterioles isolated from high-oxidative skeletal muscle [red portion of the gastrocnemius muscle (RG) and diaphragm (Dia)]. Second-order arterioles (2As) were isolated from WG, RG, and Dia of rats and reactivity examined in vitro. Results reveal that Dia 2As constrict less to norepinephrine (NE) (10−9 to 10 −4 M) than 2As from RG and WG, which exhibited similar NE-induced constrictions. This difference was not endothelium dependent, because responses of denuded 2As were similar to those of intact arterioles. The blunted NE-induced constrictor response of Dia 2As appears to be the result of differences in α1-receptor effects because 1) arterioles from Dia also responded less to selective α1-receptor stimulation with phenylephrine than RG and WG arterioles; 2) arterioles from Dia, RG, and WG dilated similarly to isoproterenol (10−9 to 10−4 M) and did not respond to selective α2-receptor stimulation with UK-14304; and 3) endothelin-1 produced similar constriction in 2As from Dia, RG, and WG. We conclude that differences in oxidative capacity and/or fiber type composition of muscle tissue do not explain different NE responsiveness of Dia 2As compared with 2As from gastrocnemius muscle. Differences in α1-adrenergic constrictor responsiveness among arterioles in skeletal muscle may contribute to nonuniform muscle blood flow responses observed during exercise and serve to maintain blood flow to Dia during exercise-induced increases in sympathetic nerve activity.

Molecular and kinetic alterations of muscle AMP deaminase during chronic creatine depletion

1998 ◽  
Vol 274 (2) ◽  
pp. C465-C471 ◽  
Author(s):  
James W. E. Rush ◽  
Peter C. Tullson ◽  
Ronald L. Terjung
Keyword(s):  
Gastrocnemius Muscle ◽  
Amp Deaminase ◽  
Soluble Cell ◽  
Fast Twitch Muscle ◽  
Fast Twitch ◽  
Menten Constant ◽  
Soluble Cell Fraction

We examined a possible mechanism to account for the maintenance of peak AMP deamination rate in fast-twitch muscle of rats fed the creatine analog β-guanidinopropionic acid (β-GPA), in spite of reduced abundance of the enzyme AMP deaminase (AMPD). AMPD enzymatic capacity (determined at saturating AMP concentration) and AMPD protein abundance (Western blot) were coordinately reduced ∼80% in fast-twitch white gastrocnemius muscle by β-GPA feeding over 7 wk. Kinetic analysis of AMPD in the soluble cell fraction demonstrated a single Michaelis-Menten constant ( K m; ∼1.5 mM) in control muscle extracts. An additional high-affinity K m (∼0.03 mM) was revealed at low AMP concentrations in extracts of β-GPA-treated muscle. The kinetic alteration in AMPD reflects increased molecular activity at low AMP concentrations; this could account for high rates of deamination in β-GPA-treated muscle in situ, despite the loss of AMPD enzyme protein. The elimination of this kinetic effect by treatment of β-GPA-treated muscle extracts with acid phosphatase in vitro suggests that phosphorylation is involved in the kinetic control of skeletal muscle AMPD in vivo.

scholarly journals Adrenergic control of vascular resistance varies in muscles composed of different fiber types: influence of the vascular endothelium

2011 ◽  
Vol 301 (3) ◽  
pp. R783-R790 ◽  
Author(s):  
Bradley J. Behnke ◽  
Robert B. Armstrong ◽  
Michael D. Delp
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Vascular Endothelium ◽  
Fold Increase ◽  
Male Rats ◽  
Type I ◽  
Fiber Types ◽  
Fast Twitch Muscle ◽  
Dose Responses ◽  
Fast Twitch

The influence of the sympathetic nervous system (SNS) upon vascular resistance is more profound in muscles comprised predominately of low-oxidative type IIB vs. high-oxidative type I fiber types. However, within muscles containing high-oxidative type IIA and IIX fibers, the role of the SNS on vasomotor tone is not well established. The purpose of this study was to examine the influence of sympathetic neural vasoconstrictor tone in muscles composed of different fiber types. In adult male rats, blood flow to the red and white portions of the gastrocnemius (GastRed and GastWhite, respectively) and the soleus muscle was measured pre- and postdenervation. Resistance arterioles from these muscles were removed, and dose responses to α1-phenylephrine or α2-clonidine adrenoreceptor agonists were determined with and without the vascular endothelium. Denervation resulted in a 2.7-fold increase in blood flow to the soleus and GastRed and an 8.7-fold increase in flow to the GastWhite. In isolated arterioles, α2-mediated vasoconstriction was greatest in GastWhite (∼50%) and less in GastRed (∼31%) and soleus (∼17%); differences among arterioles were abolished with the removal of the endothelium. There was greater sensitivity to α1-mediated vasoconstriction in the GastWhite and GastRed vs. the soleus, which was independent of whether the endothelium was present. These data indicate that 1) control of vascular resistance by the SNS in high-oxidative, fast-twitch muscle is intermediate to that of low-oxidative, fast-twitch and high-oxidative, slow-twitch muscles; and 2) the ability of the SNS to control blood flow to low-oxidative type IIB muscle appears to be mediated through postsynaptic α1- and α2-adrenoreceptors on the vascular smooth muscle.

Blood flow to different skeletal muscle fiber types during contraction

1983 ◽  
Vol 245 (2) ◽  
pp. H265-H275 ◽  
Author(s):  
B. G. Mackie ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Oxidative Capacity ◽  
Skeletal Muscle Fiber ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Blood Flows ◽  
Fast Twitch

Blood flow to fast-twitch red (FTR), fast-twitch white (FTW), and slow-twitch red (STR) muscle fiber sections of the gastrocnemius-plantaris-soleus muscle group was determined using 15 +/- 3-microns microspheres during in situ stimulation in pentobarbital-anesthetized rats. Steady-state blood flows were assessed during the 10th min of contraction using twitch (0.1, 0.5, 1, 3, and 5 Hz) and tetanic (7.5, 15, 30, 60, and 120/min) stimulation conditions. In addition, an earlier blood flow determination was begun at 3 min (twitch series) or at 30 s (tetanic series) of stimulation. Blood flow was highest in the FTR (220-240 ml X min-1 X 100 g-1), intermediate in the STR (140), and lowest in the FTW (70-80) section during tetanic contraction conditions estimated to coincide with the peak aerobic function of each fiber type. These blood flows are fairly proportional to the differences in oxidative capacity among fiber types. Further, their absolute values are similar to those predicted from the relationship between blood flow and oxidative capacity found by others for dog and cat muscles. During low-frequency contraction conditions, initial blood flow to the FTR and STR sections were excessively high and not dependent on contraction frequency. However, blood flows subsequently decreased to values in keeping with the relative energy demands. In contrast, FTW muscle did not exhibit this time-dependent relative hyperemia. Thus, besides the obvious quantitative differences between skeletal muscle fiber types, there are qualitative differences in blood flow response during contractions. Our findings establish that, based on fiber type composition, a heterogeneity in blood flow distribution can occur within a whole muscle during contraction.

In vitro O2 uptake and histochemical fiber type of resting hamster muscles

1984 ◽  
Vol 57 (1) ◽  
pp. 246-253 ◽  
Author(s):  
S. M. Sullivan ◽  
R. N. Pittman
Keyword(s):  
Surface Area ◽  
Fiber Type ◽  
Oxidative Capacity ◽  
Histochemical Staining ◽  
Striated Muscles ◽  
Type Composition ◽  
Slow Twitch ◽  
Pattern Number ◽  
Fast Twitch

In vitro oxygen consumption (VO2), histochemical fiber type, capillary arrangement, and muscle fiber geometry were measured in three hamster striated muscles. These muscles varied markedly in their histochemical fiber type composition (% by number): retractor (70% FG, fast-twitch, glycolytic; 16% FOG, fast-twitch, oxidative-glycolytic; 14% SO, slow-twitch, oxidative); soleus (57% FOG, 43% SO), and sartorius (98% FG, 2% FOG). Sartorius VO2 [0.80 +/- 0.034 (SE) ml O2 X min-1 X 100 g-1] was significantly different (P less than 0.01) from VO2 of retractor (0.89 +/- 0.038) and soleus (1.00 +/- 0.048).The number of capillaries around a fiber and the surface area/volume were greater for FOG and SO fibers than for FG fibers. Fibers of all types appeared to be roughly elliptical in shape. Capillaries were uniformly distributed around fibers in the soleus, but they were located more toward the ends of the major diameter in the retractor and sartorius. The results suggest a relationship among a fiber's oxidative capacity (based on its histochemical staining pattern), number of surrounding capillaries and surface area/volume. Furthermore, results suggest that VO2 and capillary spacing around a fiber may depend on fiber type.

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