EFFECT OF VERAPAMIL ON THE CONTRACTILE PROPERTIES OF LEAD—TREATED ISOLATED ARTERY

Introduction. Diacutaneous Fibrolysis is defined as specific instrumental intervention to normalize function in the musculoskeletal system. It is considered a treatment method for the mechanical alterations of the locomotor system, and it is widely used in sports for therapeutic and preventive purposes. Despite the clinical benefits observed in different musculoskeletal conditions, the action mechanism of diacutaneous fibrolysis remains uncertain. There are no studies evaluating the neuromuscular response on the posterior muscular chain of the lower extremity in athletes, where overload, stiffness, and injury incidence are high. Objective. To evaluate the immediate, and 30 min post treatment effects of a single diacutaneous fibrolysis session on passive neuromuscular response and mechanosensitibity on hamstring and gluteus in athletes with shortening. Design. A randomized within participant clinical trial. Methods. Sixty-six athletes with hamstring shortening were included (PKE < 160). The lower limbs were randomized between the experimental limb and control limb, regardless of dominance. A single session of diacutaneous fibrolysis was applied to the posterior gluteus maximus, biceps femoris, and semitendinosus of the experimental lower limb whereas the control limb was not treated. Viscoelastic muscle properties (myotonometry), contractile muscle properties (tensomiography), and mechanosensitivity (algometry) were tested before treatment (T0), after treatment (T1), and 30 min post treatment (T2). Results. Regarding viscoelastic properties, in the intra-group analysis we found statistically significant differences in the experimental limb at T1, decreasing muscle stiffness in gluteus maximus (p < 0.042), in biceps femoris (p < 0.001) and in semitendinosus (p < 0.032). We also observed statistically significant differences in Tone decrease (p < 0.011) and relaxation increase (p < 0.001) in biceps femoris. At T2, the decrease in stiffness in all tested muscles was maintained (p < 0.05). There were statistically significant inter-groups differences in stiffness on gluteus (p < 0.048) and biceps femoris (p < 0.019) and in tone on biceps femoris (p < 0.009) compared to the control limb. For contractile properties, we only found statistically significant differences on maximal radial displacement (Dm) in gluteus, both control and experimental at T2 (p < 0.05) and in biceps femoris control (p < 0.030). No changes were found in the mechanosensitivity. Conclusions. A single session of diacutaneous fibrolysis produces changes in some parameters related to viscoelasticity properties of the biceps femoris and gluteus. There were no changes on contractile properties on semitendinosus. Only small changes on the contractile properties on the gluteus maximus and biceps femoris were found. No effect was found on the mechanosensitivity of the posterior chain muscles in athletes with hamstring shortening.

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Contractile properties of actomyosin from human blood platelets

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)30392-7 ◽

1978 ◽

Vol 253 (15) ◽

pp. 5443-5447

Author(s):

E.A. Lebowitz ◽

R. Cooke

Keyword(s):

Human Blood ◽

Blood Platelets ◽

Contractile Properties ◽

Human Blood Platelets

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Right ventricular longitudinal strain with CMR can more accurately estimate right ventricular functional reserve in rats with pulmonary arterial hypertension

European Heart Journal ◽

10.1093/ehjci/ehaa946.0225 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

H Sato ◽

Y Someya ◽

Y Takahashi ◽

K Kumasaka ◽

W Sato ◽

...

Keyword(s):

Pulmonary Arterial Hypertension ◽

Arterial Hypertension ◽

Right Ventricular ◽

Longitudinal Strain ◽

Weight Ratio ◽

Contractile Properties ◽

Funding Source ◽

Functional Reserve ◽

Pulmonary Arterial ◽

Cmr Imaging

Abstract Background Right ventricular (RV) function is an important prognostic factor in patients with pulmonary arterial hypertension (PAH). Recently, CMR has become an attractive modality for follow up and providing prognosis in the patients, and strain has been used as a newer parameter to assess contractile properties of ventricle. It has not yet been established, however, whether RV strain with CMR can estimate RV functional reserve in the patients with PAH. Purpose We focused on CMR imaging of RV, investigating whether RV longitudinal strain can estimate RV functional reserve using a rat model with PAH. Method Rats were given a subcutaneous injection of 60 mg/kg monocrotaline (MCT-rats) or solvent (Ctr-rats). Four weeks after the injection, 25% of MCT-rats died due to RV failure. In the survivors of MCT- (n=19) and Ctr-rats (n=5), retrospective ECG-gated cine MR (16 phases/beat) was imaged with a 7T scanner. Subsequently, we measured RV pressure (RVP) via right internal jugular vein and dissected trabeculae (length = 1.45±0.07 mm, width = 334±27 μm, thickness = 114±6 μm) from RVs. We calculated weight ratio of RV free wall to left ventricle (LV) by RV/(LV+septum). Trabeculae were electrically stimulated with 2-s stimulus intervals, and force was measured using a silicon strain gauge (0.7 mM extracellular Ca2+, 24°C). To determine contractile properties of RV muscle, dF/dt was calculated. Using CMR imaging, we measured RV ejection fraction (RVEF) and RV longitudinal strain (RVLS). To modulate RVP, we intravenously injected 5 nmol endothelin-1 (ET-1) and again measured RVEF and RVLS. Results MCT-rats showed higher systolic RVP (62.5±16.6 vs. 25.9±1.86 mmHg, p<0.01) and higher weight ratio of RV (0.60±0.03 vs. 0.28±0.02, p<0.05). In CMR imaging, MCT-rats showed lower RVEF (36.1±11.2 vs. 64.8±8.4%, p<0.001) and lower RVLS (−18±9 vs. −30±1%, p<0.05). In trabeculae from RVs, MCT-rats showed lower developed force and lower dF/dt (p<0.01). Correlation between RVLS and dF/dt was higher (n=20, r=0.53, p<0.05) than that between RVEF and dF/dt (r=0.24). In addition, RVLS and dF/dt had already been decreased in 5 MCT-rats with relatively preserved RVEF (>50%), suggesting that RVLS decreases earlier than RVEF in MCT-rats. Ten minutes after the injection of ET-1, RVP was increased from 49.4±7.9 to 57.9±6.4 mmHg in MCT-rats (n=6). In MCT-rats with preserved RVEF and decreased RVLS, the increase in RVP chiefly decreased RVEF while it did not change RVLS and RVEF in Ctr-rats, meaning that RV functional reserve had been decreased in MCT-rats. In trabeculae, developed force and dF/dt were increased after the addition of 0.1 μM ET-1 in MCT- (n=11, p<0.01) and Ctr-rats (n=4, p<0.01). Conclusion These results suggest that in rats with PAH, RVLS obtained from CMR can estimate RV functional reserve earlier and more accurately than RVEF. Therefore, RV strain with CMR may become an important parameter to assess RV functional reserve in patients with PAH. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Young Scientists

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Pharmacological block of chloride channels of developing rat skeletal muscle affects the differentiation of specific contractile properties

Pflügers Archiv - European Journal of Physiology ◽

10.1007/bf00370216 ◽

1990 ◽

Vol 416 (1-2) ◽

pp. 17-21 ◽

Cited By ~ 18

Author(s):

A. De Luca ◽

D. Conte Camerino ◽

A. Connold ◽

G. Vrbovà

Keyword(s):

Skeletal Muscle ◽

Chloride Channels ◽

Contractile Properties ◽

Rat Skeletal Muscle ◽

Developing Rat

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Active Stretch-Shorten Contractions of the M. Pectoralis in the European Starling (Sturnus Vulgaris): Evidence From Electromyography and Contractile Properties

Netherlands Journal of Zoology ◽

10.1163/156854289x00219 ◽

1989 ◽

Vol 40 (1-2) ◽

pp. 106-114 ◽

Cited By ~ 4

Author(s):

K.P. Dial ◽

G.E. Goslow

Keyword(s):

Sturnus Vulgaris ◽

European Starling ◽

Contractile Properties

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Effects of hypertensive plasma on the responses of an isolated artery preparation to noradrenaline

Cardiovascular Research ◽

10.1093/cvr/10.2.268 ◽

1976 ◽

Vol 10 (2) ◽

pp. 268-274 ◽

Cited By ~ 25

Author(s):

D. S. BLOOM ◽

M. G. STEIN ◽

C. ROSENDORFF

Keyword(s):

Isolated Artery

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Differential effects of targeted tongue exercise and treadmill running on aging tongue muscle structure and contractile properties

Journal of Applied Physiology ◽

10.1152/japplphysiol.01370.2012 ◽

2013 ◽

Vol 114 (4) ◽

pp. 472-481 ◽

Cited By ~ 28

Author(s):

Heidi Kletzien ◽

John A. Russell ◽

Glen E. Leverson ◽

Nadine P. Connor

Keyword(s):

Young Adult ◽

Exercise Group ◽

Contractile Properties ◽

Treadmill Running ◽

Brown Norway ◽

Middle Aged ◽

Adult Rats ◽

Tongue Muscle ◽

Muscle Structure ◽

Old Rats

Age-associated changes in tongue muscle structure and strength may contribute to dysphagia in elderly people. Tongue exercise is a current treatment option. We hypothesized that targeted tongue exercise and nontargeted exercise that activates tongue muscles as a consequence of increased respiratory drive, such as treadmill running, are associated with different patterns of tongue muscle contraction and genioglossus (GG) muscle biochemistry. Thirty-one young adult, 34 middle-aged, and 37 old Fischer 344/Brown Norway rats received either targeted tongue exercise, treadmill running, or no exercise (5 days/wk for 8 wk). Protrusive tongue muscle contractile properties and myosin heavy chain (MHC) composition in the GG were examined at the end of 8 wk across groups. Significant age effects were found for maximal twitch and tetanic tension (greatest in young adult rats), MHCIIb (highest proportion in young adult rats), MHCIIx (highest proportion in middle-aged and old rats), and MHCI (highest proportion in old rats). The targeted tongue exercise group had the greatest maximal twitch tension and the highest proportion of MHCI. The treadmill running group had the shortest half-decay time, the lowest proportion of MHCIIa, and the highest proportion of MHCIIb. Fatigue was significantly less in the young adult treadmill running group and the old targeted tongue exercise group than in other groups. Thus, tongue muscle structure and contractile properties were affected by both targeted tongue exercise and treadmill running, but in different ways. Studies geared toward optimizing dose and manner of providing targeted and generalized tongue exercise may lead to alternative tongue exercise delivery strategies.

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