Biventer Muscle Research Articles

Three in one - unusual palmaris longus muscle anatomical variation.

The palmaris longus muscle (PLM) is one of the most variable muscles in human body, pre-senting a wide range of morphological variants such as reversed course, biventer muscle, bi-furcated tendon or total agenesis. Their clinical impact is particularly important in diagnosis and treatment of carpal tunnel syndrome and reconstructive surgery. We present a case of PLM including a previously undescribed combination of variations. A routine dissection of male cadaver aged approximately 60 demonstrated a biventer muscle, with superior and inferior belly being interrupted by a long tendon. The inferior belly passed deep to the flexor retinaculum and its terminal tendon connected to flexor digitorum superfi-cialis tendon for 5th finger. The clinical importance of variations found have been described separately, including unsuita-bility of biventer muscles for tendon reconstruction and increased risk for developing carpal tunnel syndrome in patients with PLM tendon passing deep to the flexor retinaculum. In conclusion, as another variation of PLM is described, it is crucial to bear in mind the poten-tial morphological types of the muscle in diagnosis and treatment of patients, especially in surgery of the hand and forearm.

In vitro toxic effects of puff adder (Bitis arietans) venom, and their neutralization by antivenom.

This study investigated the in vitro toxic effects of Bitis arietans venom and the ability of antivenom produced by the South African Institute of Medical Research (SAIMR) to neutralize these effects. The venom (50 µg/mL) reduced nerve-mediated twitches of the chick biventer muscle to 19% ± 2% of initial magnitude (n = 4) within 2 h. This inhibitory effect of the venom was significantly attenuated by prior incubation of tissues with SAIMR antivenom (0.864 µg/µL; 67% ± 4%; P < 0.05; n = 3–5, unpaired t-test). Addition of antivenom at t50 failed to prevent further inhibition or reverse the inhibition of twitches and responses to agonists. The myotoxic action of the venom (50 µg/mL) was evidenced by a decrease in direct twitches (30% ± 6% of the initial twitch magnitude) and increase in baseline tension (by 0.7 ± 0.3 g within 3 h) of the chick biventer. Antivenom failed to block these effects. Antivenom however prevented the venom induced cytotoxic effects on L6 skeletal muscle cells. Venom induced a marginal but significant reduction in plasma clotting times at concentrations above 7.8 µg/100 µL of plasma, indicating poor procoagulant effects. In addition, the results of western immunoblotting indicate strong immunoreactivity with venom proteins, thus warranting further detailed studies on the neutralization of the effects of individual venom toxins by antivenom.

Some pharmacological actions of acetylsecohemicholinium.

The effects of the acetylated derivative of HC-3 (acetylsecohemicholinium; AcHC-3) have been studied at cholinergic nerve terminals and compared with the effects of the parent compound. AcHC-3 blocked neuromuscular transmission in nerve-muscle preparations; it was shown to be less effective than HC-3 in producing a pre-junctional block in the rat diaphragm but was more effective than HC-3 in eliciting a post-junctional blocking effect in the chick biventer muscle. On the frog rectus abdominis muscle AcHC-3 caused a substantial potentiation of the contractures elicited by acetylcholine but did not by itself cause a contracture of the muscle. AcHC-3 inhibited the synthesis of acetylcholine by cholinergic nerve ending particles and inhibited the uptake of [14C]choline into brain synaptosomal fractions to a similar extent to HC-3. AcHC-3 was shown to be a substrate for cholinesterase enzymes although the rate of hydrolysis was much less than the rate of hydrolysis of acetylcholine. It is concluded that AcHC-3 is effective in inhibiting cholinergic transmission and this action is exerted by the open chain (seco) compound and is not due to the hydrolysis of the AcHC-3 by cholinesterases to form the active HC-3 molecule.

IN VITRO NEUROTOXIC AND MYOTOXIC EFFECTS OF THE VENOM FROM THE BLACK WHIP SNAKE (DEMANSIA PAPUENSIS)

1. Black whip snakes belong to the family elapidae and are found throughout the northern coastal region of Australia. The black whip snake (Demansia papuensis) is considered to be potentially dangerous due to its size and phylogenetic distinctiveness. Previous liquid chromatography-mass spectrometry analysis of D. papuensis venom indicated a number of components within the molecular mass ranges compatible with neurotoxins. For the first time, this study examines the in vitro neurotoxic and myotoxic effects of the venom from D. papuensis. 2. Venom (10 microg/mL) caused significant inhibition of twitches elicited by stimulation (0.2 ms, 0.1 Hz, supramaximal V) of motor nerves in the chick biventer cervicis nerve-muscle preparation. This neurotoxic effect, which was postsynaptic in origin, was weak in comparison to that of most other Australian elapids. Prior addition (10 min) of polyvalent (PSAV) or tiger snake (TSAV) antivenom (5 units/mL) prevented venom-induced twitch inhibition. Addition of PSAV (5 units/mL) at t(50) failed to reverse the inhibitory effect but prevented further inhibition of nerve-mediated twitches. 3. The venom (20-50 microg/mL) is also myotoxic as indicated by a slowly developing contracture and inhibition of twitches elicited by direct stimulation (2 ms, 0.1 Hz, supramaximal V, in the presence of tubocurarine 10 micromol/L) of the chick biventer muscle. This activity was confirmed by histological examination of the muscle. 4. Fractionation and characterization of venom components is required to further investigate the reasons for the weak neurotoxic activity of D. papuensis venom.

Comparison of the in vitro neuromuscular activity of venom from three australian snakes (Hoplocephalus stephensi, Austrelaps superbus and Notechis scutatus): Efficacy of tiger snake antivenom

1. Tiger snake antivenom, raised against Notechis scutatus venom, is indicated not only for the treatment of envenomation by this snake, but also that of the copperhead (Austrelaps superbus) and Stephen's banded snake (Hoplocephalus stephensi). The present study compared the neuromuscular pharmacology of venom from these snakes and the in vitro efficacy of tiger snake antivenom. 2. In chick biventer cervicis muscle and mouse phrenic nerve diaphragm preparations, all venoms (3-10 microg/mL) produced inhibition of indirect twitches. In the biventer muscle, venoms (10 micro g/mL) inhibited responses to acetylcholine (1 mmol/L) and carbachol (20 micromol/L), but not KCl (40 mmol/L). The prior (10 min) administration of 1 unit/mL antivenom markedly attenuated the neurotoxic effects of A. superbus and N. scutatus venoms (10 microg/mL), but was less effective against H. stephensi venom (10 microg/mL); 5 units/mL antivenom attenuated the neurotoxic activity of all venoms. 3. Administration of 5 units/mL antivenom at t90 partially reversed, over a period of 3 h, the inhibition of twitches produced by N. scutatus (10 microg/mL; 41% recovery), A. superbus (10 microg/mL; 25% recovery) and H. stephensi (10 microg/mL; 50% recovery) venoms. All venoms (10-100 microg/mL) also displayed signs of in vitro myotoxicity. 4. The results of the present study indicate that all three venoms contain neurotoxic activity that is effectively attenuated by tiger snake antivenom.

Anionic Cyclophanes as Potential Reversal Agents of Muscle Relaxants by Chemical Chelation

A series of carboxyl-containing cyclophanes have been designed and synthesised as chemical chelators (or host molecules) of cationic muscle relaxant drugs (or guest molecules). Three of these cyclophane derivatives, 1– 3, have been shown by NMR to form 1:1 complexes with the muscle relaxants pancuronium, 4 and gallamine, 5 in D 2O, with association constants up to 10 4 M −1. When tested in an in vitro chick biventer muscle preparation, the cyclophanes reversed the neuromuscular block induced by pancuronium and gallamine, with 3 having the most effective reversal against pancuronium (EC 50 40 μM).

Biochemical and pharmacological characterization of the venom of the black scorpion Heterometrus spinifer

The sting of the black scorpion Heterometrus spinifer, which can cause intense localized pain, has not been reported to produce lethal cardiovascular complications, which are well known to result from scorpion envenomation as a consequence of a massive release of catecholamines. Therefore, we have undertaken a biochemical and pharmacological characterization of the venom of H. spinifer. Pharmacologically, the venom (0.125 μL/mL) produced a marked, reversible contracture in the chick biventer cervicis muscle that was blocked by d-tubocurarine (2 μM) but not by tetrodotoxin (5 μM) and ω-conotoxin GVIA (3 μM). The anticholinesterase neostigmine (1 μM) potentiated the contracture by 5.3-fold. An ultra-filtrate fraction of MW < 3000 (F3K) of the venom produced a similar contracture in the biventer muscle, whereas the retentate of MW > 3000 did not. In the rat anococcygeus muscle, the venom produced a contractile response that was partially (37.4 ± 1.6%) blocked by atropine (5 μM); phentolamine (5 μM) blocked the remaining response. Tetrodotoxin (5 μM) did not block the contractile response of the venom on the anococcygeus muscle. Electrospray ionization-mass spectrometry/mass spectrometry confirmed the presence of high concentrations of acetylcholine (79.8 ± 1.7 μM) and norepinephrine (146.7 ± 19.8 μM) in H. spinifer venom, which can fully account for the observed cholinergic and adrenergic effects. In contrast to scorpion venoms that selectively target neuronal ion channels in mediating transmitter release, our data show that H. spinifer venom does not possess such activity, which likely explains the apparent lack of lethality of black scorpion envenomation.

A pharmacological examination of venoms from three species of death adder ( Acanthophis antarcticus, Acanthophis praelongus and Acanthophis pyrrhus)

The common ( A. antarcticus), northern ( A. praelongus) and desert ( A. pyrrhus) death adders are species belonging to the Acanthophis genus. The present study compared some pharmacological aspects of the venoms of these species and examined the in vitro efficacy of death adder antivenom. Neurotoxicity was determined by the time to produce 90% inhibition ( t 90) of indirect (0.1 Hz, 0.2 ms, supramaximal voltage) twitches in the chick biventer cervicis nerve-muscle (3–10 μg/ml) and mouse phrenic nerve-diaphragm (10 μg/ml) preparations. A. praelongus venom was significantly less neurotoxic than A. antarcticus venom but was not significantly different from A. pyrrhus venom. In the biventer muscle, all three venoms (3–10 μg/ml) abolished responses to exogenous ACh (1 mM) and carbachol (20 μM), but not KCl (40 mM), indicating activity at post-synaptic nicotinic receptors. All venoms (30 μg/ml) failed to produce significant inhibition of direct twitches (0.1 Hz, 2.0 ms, supramaximal voltage) in the chick biventer cervicis nerve-muscle preparation. However, A. praelongus (30 μg/ml) venom initiated a significant direct contracture of muscle, indicative of some myotoxic activity. The prior (10 min) administration of death adder antivenom (1 unit/ml), which is raised against A. antarcticus venom, markedly attenuated the twitch blockade produced by all venoms (10 μg/ml). Administration of antivenom (1.5 units/ml) at t 90 markedly reversed, over a period of 4 h, the inhibition of twitches produced by A. praelongus (3 μg/ml, 72±6% recovery) and A. pyrrhus (3 μg/ml, 51±9% recovery) but was less effective against A. antarcticus venom (3 μg/ml, 22±7% recovery). These results suggest that all three venoms contain postsynaptic neurotoxins. Death adder antivenom displayed differing efficacy against the in vitro neurotoxicity of the three venoms.

A pharmacological examination of venom from the Papuan taipan: ( Oxyuranus scutellatus canni)

The Papuan taipan ( Oxyuranus scutellatus canni) is the third most venomous terrestrial snake in the world, however, little is know about the pharmacology of the venom. In the chick biventer cervicis muscle, venom (10 μg/ml) abolished nerve-mediated twitches (time to 90% inhibition ( t 90) 44±5 min, n=9). This inhibition was unaffected by prior incubation of the venom with the phospholipase A inhibitor 4-bromophenacyl bromide (4-BPB; 0.72 mM) ( t 90 48±7 min, n=8). The mouse phrenic nerve diaphragm preparation displayed greater sensitivity to venom (10 μg/ml) ( t 90 25±1 min, n=6). In the chick biventer muscle, venom (10 μg/ml) significantly inhibited responses to acetylcholine (1 mM) and carbachol (20 μM), but not KCl (40 mM), indicating activity at post-synaptic nicotinic receptors. Venom (10 μg/ml) did not affect direct muscle stimulation. Venom (3–30 μg/ml) produced dose-dependant contractions of the guinea-pig ileum. Contractile responses were significantly inhibited by indomethacin (1 μM) or prior incubation of the venom with 4-BPB (0.72 mM) indicating involvement of a PLA component. In rat phenylephrine (0.3 μM) precontracted aortae, venom (3–100 μg/ml) produced endothelium-independent relaxation which was unaffected by prior incubation of venom (30 μg/ml) with 4-BPB (0.72 mM). In anaesthetised rats, 10 μg/kg (i.v.) venom produced rapid respiratory and cardiovascular collapse while 5 μg/kg (i.v.) venom produced only a small transient decrease in mean arterial blood pressure. Prior administration of 5 μg/kg (i.v.) venom enabled subsequent administration of 10 and 100 μg/kg (i.v.) venom without respiratory or cardiovascular collapse. Further work is required to identify specific toxins with the above pharmacological activity.

A comparison of the potency and specificity of the direct muscle relaxant activity of azumolene and dantrolene

AbstractDantrolene is a unique directly acting skeletal muscle relaxant that is clinically useful in the treatment of chronic muscle spasticity and malignant hyperthermia. Azumolene is a new dantrolene‐like drug that has better aqueous solubility and that may also be of use in the treatment of acute muscle spasm. Potency of both compounds was determined in the anesthetized, curarized rat gastrocnemius (using different routes of administration) and the isolated chick biventer muscle preparations. The specificity of effects in vitro was evaluated by comparing effects in the chick biventer with those seen in the rat aortic strip. Route of administration governed potency for both drugs, with rank order i.v., i.p., and i.d. being the least potent. In vivo, dantrolene was approximately twice as potent as azumolene when administered by any of the routes tested. However, both drugs are equipotent in vitro. Reasons for the discrepancy between in vivo and in vitro potencies are discussed. The muscle relaxant effects of both azumolene and dantrolene are specific for skeletal muscle, being 10‐fold more potent in skeletal than in arterial smooth muscle. The reasons for this specificity are probably due to basic differences in the physiology of smooth and skeletal muscle. We conclude that the new agent, azumolene, is a specific, potent skeletal muscle relaxant with properties qualitatively similar to those of dantrolene.

Neuromuscular effects of three phospholipases A 2 from the venom of the Australian king brown snake Pseudechis australis

—Three single chain phospholipases A 2 (Pa-10A, Pa-11 and Pa-13) isolated from Australian king brown snake ( Pseudechis australis) venom were tested for effects on neuromuscular transmission and muscle contractility on chick biventer cervicis and mouse diaphragm preparations. At 1 μg/ml (about 85 nM) and higher, Pa-10A and Pa-11 reduced responses of both preparations to indirect stimulation in a concentration-dependent manner. Responses to direct muscle stimulation were generally reduced more slowly. Pa-11 also decreased membrane potentials of chick biventer muscle fibres and caused damage visible by light microscopy. Pa-13, which is about 50 times less active as a phospholipase A 2, was also less potent in its pharmacological effects: 20 μg Pa-13 per ml were required to reduce responses of either preparation. The phospholipases A 2 also caused a slow contracture. After block of responses to nerve stimulation, responses of the chick preparation to acetylcholine, carbachol and KCl could be obtained, although they were smaller than control and highly variable in different preparations. It is concluded that Pa-10A and Pa-11 produce muscle paralysis by reducing acetylcholine release and by a direct blockade of muscle fibre contractility. Pa-13 has similar, though less pronounced, activities.

On the cervical muscles of birds

Cervical muscles in eleven Orders and nineteen species of birds were compared by semidiagramatical illustrations of the lateral view. The main series of cervical muscles studied was given the following nomenclature:1. Dorsal muscles1. Biventer muscle, M. biventer cervicalis2. Dorsal long cervical muscle, M. longus colli posticus (M. spinalis)a. Longitudinal part, pars longus b. Anterior part, pars anteriorc. Posterior part, pars posterior d. Inferior part, pars inferior3. Dorsal profound cervical muscle, M. profundus colli posticus4. Intercrestal muscle, M. intercristalisII. Lateral muscles1. Oblique cervical muscle, M. obliquus colli2. Lateral cervical muscle, M. colli lateralis (M. intertransversalis)III. Ventral muscles1. Ventral long cervical muscle, M. longus colli anticusa. Longitudinal part, pars longus b. Anterior part, pars anteriorc. Posterior part, pars posteriorThe development of these muscles is extremely variable both adaptively and possibly taxonomically and in some groups is very specialized. These complexities of the avian cervical muscle system are the natural result of their variety of uses of the neck in food-getting and other activities. The myology of this interesting and important part of avian body, however, has been curiously neglected and is open to future detailed comparative studies.