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PubMed1996

Chlorpromazine and diltiazem effects in muscle: blockage of acetylcholine-evoked contractures, membrane currents and tracer calcium uptake.

Contractures evoked by 0.1 mmol/l acetylcholine (ACh) in bundles from mouse soleus muscles denervated for 3-7 days were partly inhibited for more than 1 h following 2- to 10-min exposure to 10-100 mumol/l chlorpromazine (CP). The effect was stronger in sucrose than in Na+ solutions. A prolonged ACh-contracture blockage by diltiazem (20 mumol/l) was found only in the sucrose solution. Membrane currents evoked by ACh in the absence of Na+ were blocked by both the drugs, but recovered to more than 60% within 1 min of drug washout. ACh-evoked retention of tracer 45Ca2+ was decreased by more than 90 or 70% when CP or diltiazem, respectively, were applied and washed away 10 min before addition of 45Ca2+ and ACh. The results suggest that the prolonged contracture blockage was not related to the blockage of ionic currents through the ACh-receptor channel but to a drug-induced loss of Ca(2+)-storing capacity.

Acetylcholine↗
PubMed2000

Metabolic and functional response of neonatal pig hearts to the development of ischemic contracture: is recovery possible?

The potential for functional and metabolic recovery in neonatal hearts after the development of ischemic contracture remains controversial and undefined. This study documents post-ischemic recovery of metabolism and function in the in vivo neonatal heart after the development of onset and peak ischemic contracture. In piglets on cardiopulmonary bypass, hearts were reperfused after the development of either onset (TICo) or peak (TICp) ischemic contracture. Systolic (developed and systolic function, contractility) and diastolic (diastolic function, relaxation) performance was assessed throughout reperfusion. Biopsies were obtained at end-ischemia or end-reperfusion to assess metabolism. By end-ischemia, the metabolic profiles of both TICo and TICp hearts confirmed energy-store depletion and purine degradation that was quantitatively greater in TICp hearts. Hearts reperfused at TICo had consistent moderate impairment of developed function, contractility, diastolic function, and relaxation, whereas hearts reperfused at TICp had much more profound functional impairment. Diastolic function showed the worst functional recovery. In contrast, systolic function was not significantly altered in either study group and, thus, did not reflect the actual extent of injury. In addition, TICo hearts either did not further deplete or partially regenerated energy stores during reperfusion, whereas TICp hearts had further energy-store depletion and lactate accumulation. In summary, neonatal hearts reperfused after TICo maintained or partially restored energy stores and had significant but incomplete functional recovery. In contrast, further metabolic deterioration and profound functional impairment occurred with reperfusion after TICp, potentially indicating ongoing mitochondrial injury and compromised oxidative phosphorylation.

Adenine Nucleotides↗
PubMed1977

Effects of diltiazem and lanthanum ion on the potassium contracture of isolated guinea pig smooth muscle.

Effects of diltiazem on K-induced contracture of the smooth muscle were examined in the isolated taenia coli and stomach strip of the guinea pig. Results were compared with those of lanthanum ion (La(3+)). K-contracture was evoked by isotonic K-Krebs solution. La(3+) inhibited K-contracture of the taenia coli and effects on the phasic response were found to be more remarkable than on the tonic response. After the removal of La(3+), the phasic response almost regained its normal magnitude, whereas the tonic response was significantly augmented. In contrast to the effects of La(3+), diltiazem inhibited the tonic response more markedly than the phasic response in both taenia coli and stomach strip. Inhibition of the phasic response was elicited, in association with decrease in the frequency of spike discharge during rapid depolarization of the membrane. The effects of diltiazem were completely reversed after washing out the compound. It is assumed that although both La(3+) and diltiazem inhibit the transmembrane influx of Ca(2+), additional mechanisms may differ.

Animals↗
PubMed1983

Enflurane induces contracture of in vitro muscle from a patient with malignant hyperthermia.

The possibility of enflurane being an inducer of malignant hyperthermia (MH) was examined by using the contracture test in in vitro muscle from a patient with MH. An administration of 2% enflurane elicited contracture in MH muscle and an elimination of enflurane relaxed this contracture. This result, therefore, strongly suggested that enflurane is the one of the trigger-agents for MH.

Enflurane↗
PubMed1976

Contracture and hyperpolarization of the rabbit sinoatrial node cells in Na-depleted solution.

A study was made on both hyperpolarization and contracture which developed in the rabbit sinoatrial node cell during perfusion with Na-depleted solution. The membrane was hyperpolarized in 19 out of 27 specimens (-69.5 +/- 6.0 mV), while in the remaining 8 specimens the value of the membrane potential remained low (-39.4 +/- 2.7 mV). Slope conductance increased as the membrane was hyperpolarized in Na-depleted solution, but not when the value of the membrane potential remained at low. The amplitude of hyperpolarization increased with decrease in Na concentration, increase in Ca concentration and increase in perfusate temperature. A marked increase in diastolic tension was observed in 23 out of 29 specimens but in the 6 remaining specimens the increase in tension was small. Tension increased with decrease in Na concentration, increase in Ca concentration, and increase in perfusate temperature. Pretreatment with ouabain caused a consistent increase in contracture tension, while its effect on the membrane hyperpolarization was variable among different specimens. These results may be explained by assuming that intracellular Ca concentration increased with Na-Ca exchange in Na-depleted solution. In addition to contracture, increase in intracellular Ca concentration might have caused an increase of membrane K conductance and produced marked hyperpolarization.

Animals↗
PubMed1982

The activation and inactivation in biphasic potassium contractures in frog single twitch muscle fibers.

The dependence of the occurrence of biphasic contractures on potassium chloride concentration, and the activation curve, the inactivation curve and the time-dependence curve of inactivation of the initial component of potassium contracture and those curves of the secondary component were examined, using single twitch fibers of the frog semitendinosus muscles. When single fibers having diameters of about 75-100 micrometers were used, typical biphasic contractures were clearly observed at 70-80 mM K. At 100 MM K the initial component was difficult to distinguish from the secondary component because of the fusion of both components, and at 60 and 40 mM K the initial component hardly occurred and the secondary component alone was observed. The threshold of the activation curve of the initial component (about 50-60 mM K) was higher than that of the secondary component (about 32 mM K) and also the time course of the inactivation, induced by conditioning depolarization, on the initial component did not coincide with that of the secondary component. From these results, it was concluded that the activation and inactivation processes of the excitation-contraction coupling of the initial component is different from those of the secondary component and that the efficiency of the coupling of the initial component is less than that of the secondary component. In addition, it was also indicated that each time-dependence curve of the inactivation of the initial and secondary components is biphasic, consisting of the first phase and the second phase, and that these phases have the characteristics of inactivation 1 and inactivation 2, respectively, which was proposed by us.

Animals↗
PubMed1984

Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

The effects of external Ca2+ reduction on the biphasic potassium (K) contractures and the action of divalent cations under conditions of the Ca2+ reduction were examined in detail, using frog single twitch muscle fibers. The peak tension of the initial component of 80 mM K+ contractures was greatly potentiated by exposing the fiber to low Ca2+ solution for 30 sec, and the degree of this potentiation was decreased with increasing the exposing time. In contrast, the peak tension of the secondary component was rapidly inhibited by Ca2+ reduction. The potentiation of the initial component was removed by 3 mM Mg2+ or 0.5 mM Ni2+. The inhibition of the secondary component, especially the shortening of its time course, was reversed partially by 3 mM Mg2+ and almost completely by 0.5 mM Ni2+. The difference between the inhibitory effect of 10 mM Mg2+ or 1-3 mM Ni2+ on the initial component and that on the secondary component was also demonstrated. The tension development of the secondary component was completely inhibited by external Ca2+ reduction for 20 min, but it was observed in the presence of 3 mM Mg2+, although its time course was shorter. These results indicate that the actions of Mg2+ and Ni2+ on the initial component differ from those on the secondary component and suggest the possible mechanisms of the actions of these divalent cations on the biphasic K contractures.

Animals↗
PubMed1984

Effects of divalent cations on biphasic potassium contractures and on contractile inactivation in low calcium solutions in frog single twitch muscle fibers.

When the concentration of external Ca2+ was reduced for 30 sec in a single twitch muscle fiber of a frog, the peak tension of the initial component of biphasic 80 mM K+ contractures was potentiated, whereas that of the secondary component was markedly inhibited, despite the fact that in the early stage it was potentiated usually in case of contractures in 60 and 40 nM K+ but rarely in 80 mM K+. These changes were not observed, however, in the presence of 0.5-1 nM Mn2+, i.e., Mn2+ having been substituted for Ca2+. The foregoing result and the authors' previously reported data indicated the following. First, the concentrations of divalent cations having an equal effect in bringing about the peak tensions of both components are 3 mM Mg2+, 0.7 mM Mn2+, 0.5 mM Ni2+, and 1.8 mM Ca2+. Secondly, this sequence constitutes their increasing order of effectiveness on the time course of the secondary component. Meanwhile, a similar order was found to exist in another experiment concerning the effectiveness in inhibiting the inactivation of K contractures facilitated by lowering the concentration of external Ca2+. All these findings indicated that the divalent cations act on the activation processes of both components in a stabilizing manner, differing from the way in which they act on the inactivation process of the secondary component. The mechanisms in which the peak tensions of the initial and secondary components are inhibited in a low Ca2+ solution and the divalent cations act on both components are discussed. Finally, another experiment made in the absence and presence of Ca2+ revealed that the effect of high concentrations of Mn2+ in the initial component is different from that on the secondary component.

Animals↗
PubMed1991

Ocular manifestations of congenital Marfan syndrome with contractures (CMC syndrome).

The authors present the results of ocular examination of six children with congenital Marfan syndrome with contractures (CMC syndrome). The ocular and neuroradiological findings of the CMC syndrome are discussed with reference to the literature. The ocular findings are: blue sclerae, megalocorneas, hypoplastic irides with complete translucency, miosis, spherophakia with or without lens dislocation and severe myopia. This study demonstrates that ophthalmological examination of children with congenital contractures and arachnodactyly is very helpful for diagnosis of the CMC syndrome. The authors stressed that ophthalmologists should not only look for luxation of the lens in children who are suspected of having CMC syndrome. Spherophakia was common in the children and could easily be observed through the translucent irides. Biometric evaluation of the eyes is recommended. All of the cases in this paper and reported cases are sporadic. No conclusions have been reached in the literature on whether the CMC syndrome represents the severe expression of the classical Marfan syndrome or a distinct entity. Maybe the answer will remain difficult, until the specific molecular defects in the collagen diseases are discovered. This study demonstrates that ophthalmological examination of the children with congenital contractures and arachnodactyly is very helpful for the diagnosis of CMC syndrome.

Abnormalities, Multiple↗
PubMed1991

Objective identification of ankle equinus deformity and resulting contracture.

A quantitative diagnostic technique is described for identifying contracture at the ankle joint in patients with equinus deformity, hence addressing the shortcoming of the conventional clinical diagnostic procedure. To gain a better understanding of how contracture contributes to equinus deformity, a study was designed that compared the torque about the ankle joint before and after administering a tibial nerve block to equinus patients and to a control group. Functional equinus, manifested by walking and early heel rise, is defined as inadequate dorsiflexion for normal gait. The ability to accurately identify an equinus condition, and contracture as the contributing factor in equinus deformity, has important implications for the type of treatment prescribed and the evaluation of treatment effectiveness.

Adolescent↗
PubMed1999

[Median nerve decompression in ischemic contracture of the forearm].

Ischemic contracture of the forearm known as Volkmann contracture develops from untreated (or treated to late) compartment syndrome within the forearm. Surgery is needed if function of the extremity is to be restored after fully developed Volkmann contracture. The uniform management is accepted in our Department since 1982. Multi-stage surgical treatment is indicated, the first stage consisting of median nerve neurolysis and removal of necrotic tissues to restore physiological excursion of the nerve. A series of 48 patients (16 females, 32 males aged 5-42 years) treated between 1982 and 1995 was included in the study. Complete neurolysis of the median nerve (microsurgical within proximal 1/3 of the forearm) was done in all patients. Long-term assessment of the median nerve function was done at half year to 3 years follow-up. Symptoms of nerve entrapment indicated reoperation. The study confirmed usefulness of an early median nerve decompression for prevention of neurological complications and improvement of the extremity function.

Adolescent↗
PubMedDate not supplied

[Ultrastructure of frog muscle fiber thick filaments at rest and during potassium contracture].

Isolated slow and intermediate frog muscle fibres were fixed in the rest state and under potassium contracture (50-100 mM KC1). The longitudinal and cross sections of two types of fibres were investigated. It was shown that at the rest the thick filaments of different fibres had similar length (1.6-1.65 mum), diameter (160-165 A) and the amount of subunits (12-13). Under potassium contracture the length of the thick filaments of both fibre types was shortened by 25-30% of the rest-length, the diameter of the slow fibres increased to 180-185 A, the diameter of the intermediate fibres to 200-220 A. The amount of subunits increased to 14-15 in slow fibres and to 17-18 in intermediate fibres. We believe that the ultrastructural changes observed in the thick filaments are a result of molecular transformation in these filaments, which seems to be important for maintaining the contracture.

Animals↗
PubMed1975

Ischemic contracture of the left ventricle. Production and prevention.

Ischemic contracture of the left ventricle ("stone heart") is a recognized complication of prolonged periods of interruption of the coronary circulation during open-heart surgery. We have examined the effects of moderate hypothermia (28 degrees C.) and preoperative beta-adrenergic blockade (propranolol, 0.5 mg. per kilogram; 1.0 mg. per kilogram) on contracture development during ischemic arrest of the heart. Four groups of 8 dogs each were placed on total cardiopulmonary bypass, and ischemic arrest of the heart was produced by cross-clamping the ascending aorta and venting the left ventricle. Intramyocardial carbon dioxide tension was continuously monitored by mass spectrometry. When anaerobic energy production ceased, as indicated by a final plateau in the intramyocardial carbon dioxide accumulation curve, the ischemic arrest was terminated and the contractile state of the heart observed. These results are given in the text. We conclude that beta-adrenergic blockade delays, but does not prevent, the onset of ischemic contracture of the left ventricle under normothermic conditions. Moderate hypothermia appears to prevent this complication completely.

Animals↗
PubMedDate not supplied

[Acetylcholine contracture of the fast muscle fibers in the lamprey, Lampetra fluviatilis].

Fast fibers of m. longitudinalis linguae respond to Ach by a transient contracture with a half-decay period of 3-5 sec. The threshold concentration of Ach is approximately 10(-7) g/ml. Ach contracture is based on even depolarization of the whole muscle membrane. Threshold level of the MP for the onset of contracture lies between --50 and --40 mV. In the presence of Ach depolarization decreases twofold within 40-70 sec. Relaxation is not due to the decrease of depolarization. Contraction--Ach concentration curve has a small slope; it reaches maximum at a concentration 10(-4) g/ml, which corresponds to the MP ca. -10mV. Equilibrium Ach potential is significantly shifted to depolarization as compared to that in frog muscles, being equal to +1+/-1.8 mV.

Acetylcholine↗
PubMed1977

[Exercise-induced muscular weakness, myalgia and contractures. I. A clinical review].

In the differential diagnosis of intermittent claudication some rare myopathies have to be considered. The most frequent is phosphorylase deficiency (McArdle's disease). Exercise-induced muscular pain, weakness, contractures and occasionally myoglobinuria are the most prominent clinical signs. Serum creatine phosphokinase, aldolase and lactic dehydrogenase may be elevated after exertion. In the ischemic forearm test there is no rise of serum lactic acid. The enzyme deficiency can be demonstrated by histochemical and biochemical examination of a muscle specimen. Further, but more infrequent, enzymatic disturbances of glycolysis are phosphofructokinase deficiency and phosphohexoisomerase inhibitor, which also yield an abnormal ischemic forearm test and must be demonstrated histochemically and biochemically. Apart from muscular signs, myopathy with lactic acidosis is associated with palpitation, dyspnea and exhaustion, and a disproportionate rise in serum lactic acid level after exertion. Histochemically and electronmicroscopically demonstrable fat accumulation in the muscle can be a sign of a disturbance in lipid metabolism. This type of exercise-induced myopathy has been reported only in a few cases with carnitine-pylmityltransferase deficiency, which has to be demonstrated biochemically. Muscular contractures also exercise-induced but painless and reversible within seconds may be due to deficient uptake of sarcoplasmic calcium in the tubular system. Dyskalemic paralysis causes painless paresis within minutes of hours after exertion, which disappears within hours to a few days. Myopathy with tubular aggregates can be differentiated from other exercise-induced myopathies by morphology. Myotonia combined with painful contractures characterizes myopathia myotonica.

Acidosis↗
PubMed2004

[Functioning of the electromechanical connection in the course of the contracture contraction].

The effects of calcium release blocker dantrolene was tested on electrically evoked twitches and on contractures induced by potassium depolarization, by acetylcholine or caffeine. It was shown that the first: developmental, stage of potassium or acetylcholine contracture is inhibited by dantrolene and is not influenced by calcium free medium, therefore we may interpret it as based on a "voltage-dependent Ca release" (VDCR) mechanism of activation, whereas depolarization directly opens the rhyanodin receptor calcium channels. On the contrary, the next stage: the long-lasting plateau of contracture, is directly dependent on external Ca2+ and inhibited by dantrolene, and therefore can be described as "calcium induced Ca-release" (CICR) activation mechanism. In this case stored calcium is also released by rhyanodine receptors, although by means of entering the extracellular Ca2+. Finally, the last stage of low amplitude is not influenced by dantrolene nor by calcium-free medium. Therefore the activation of contraction on this stage is not based on the Ca2+ release through the rhyanodin receptor calcium channels.

Acetylcholine↗
PubMed2005

[Repair of the knee extension apparatus in the treatment of "extension contracture" after femoral lengthening].

UNLABELLED: Restriction of the knee flexion is one of the most frequent complications during femoral lengthening with Ilizarov method. In most severe cases the knee flexion reaches less than 90 degrees, which leads to impairment of patient's activity ("extension knee contracture") and represents difficult clinical problem to manage. MATERIAL: We reviewed 4 patients at the age of 14 to 22 years (mean 19), treated surgically because of severe knee flexion limitation as a complication of femoral lengthening with the Ilizarov method. The mean age at femoral lengthening was 17 years (12 to 20). The indication for lengthening was femoral shortening from 5 to 12 cm (mean 7.5) because of myelodysplasia with club foot deformity (1 case), fibular hemimelia (1 case), sequelae of septic arthritis (1 case) and Ollier disease (1 case). Lengthening with Italian modification of Ilizarov device was used in all cases. In two patients with knee instability the apparatus was extended to stabilize the knee joint (in one case tibial and femoral lengthening was made simultaneously). Femoral lengthening of 5 to 12 cm (mean 7.5) was achieved. Knee flexion before lengthening varied from 90 degrees to 150 degrees (mean 135 degrees) and after femoral lengthening decreased to 41 degrees (20 to 75 degrees). METHOD: Plasty of knee extension apparatus was done 16 months after removal of the Ilizarov device. The procedure includes extensive release of subcutaneous and fascial adhesions around the knee joint (4 patient), patellar retinaculum and ilio-tibial tract release (4 patient), lengthening of vastus lateralis muscle (4 patients), vastus medialis (2 patients) and vastus intermedius (1 patient), mobilization of patello-femoral joint (3 patients), fractional, intramuscular lengthening of rectus femoris 15 cm above the knee joint (2 patients). Intraoperatively 90 degrees flexion was achieved (80 degrees to 100 degrees). In after treatment plaster cast with knee flexion 45 degrees was used. After 4-5 days passive exercises were started using K2 apparatus (continuous passive knee motion) and posterior slabs: one with knee extension for walking and second with knee flexion at the night were used. Active exercises began at the 10th day after surgery. RESULTS: At follow up 10 to 47 months (mean 36) after surgery 105 degrees to 120 degrees of knee flexion (mean 114 degrees) was achieved with full passive and active knee extension at good muscle power. All joints were evaluated as stable in sagittal and coronal planes (including 2 joints with mild instability in coronal plane before surgery). CONCLUSIONS: 1. Femoral lengthening procedure should be realized with proper attention to prophylaxis of knee extension contracture. 2. Knee extension apparatus plasty is effective and save procedure for treatment of so called "extension knee contracture" as a complication of femoral lengthening.

Adolescent↗
PubMed1992

A clinical comparison of the tendency to capsular contracture between smooth and textured gel-filled silicone mammary implants.

The aim of this prospective, controlled clinical investigation was to find out if there is a difference in the capsular contracture rate between silicone implants with a smooth or textured surface as the only difference. Twenty-five women with bilateral mammary hypoplasia underwent mammary augmentation. All got a textured implant on one side and a smooth implant on the other. The implants were placed subglandularly. Follow-up examinations were done on six occasions. Three parameters were used for estimation of the tendency to capsular contracture: (1) the patient's opinion on differences in hardness of the breasts, (2) the investigator's classification of capsular contracture, and (3) applanation tonometry. At the end of the follow-up period, after 1 year, all parameters showed with no doubt that the breasts augmented with textured implants had a lower tendency to develop contracting capsules than the breasts augmented with smooth implants.

Adult↗