Effects of beta-bungarotoxin on calcium uptake by sarcoplasmic reticulum from rabbit skeletal muscle

A fluorescent chelate probe and a Millipore filtration technique have been used to study the effects of β-bungarotoxin (β-toxin) on passive and active Ca⁺⁺ uptake and ATPase in fragmented sarcoplasmic reticulum (SR) of rabbit skeletal muscle. β-Toxin at 3 × 10^?6 M did not affect ATPase activity. In the absence of ATP, β-Toxin increased the passive uptake of Ca⁺⁺; in the presence of ATP, active Ca⁺⁺ uptake was inhibited. The effect of β-toxin in SR can be detected at concentrations as low as 10^?9 M. The results suggest that β-toxin induces Ca⁺⁺ leakage in SR membranes.     

Selective sympathetic denervation induced by 6-hydroxy-dopamine in the small intestine.

The structure of the nerve fibres in the intact and neurally isolated intestine of the cat was studied after 6-OHDA treatment by fluorescence and electron microscopy. A gradual disappearance of green fluorescence in the monoaminergic fibers was observed. Degeneration of nerve fibres containing 30--60 nm agranular and 30--60 nm densecore (granular) vesicles could be seen in all layers of the small intestine. Sporadically, degeneration of the presynaptic elements occurred also in the synapses of myenteric ganglia. A large number of degenerating fibres could be observed in close relation to blood vessels. These were thought to be monoaminergic because 6-OHDA selectively affected their terminals. In the chronically isolated small intestine degenerated nerve processes could not be observed following 6-OHDA treatment. It is concluded that the intrinsic nerve elements do not contain monoamines. Accordingly, the previously observed yellow fluorescence of the nerve elements of the isolated small intestine might be due to some other kind of neurotransmitter, possibly tryptamine.     

Induction of action potentials in fish red muscle by denervation

The effects of denervation on the electrical membrane properties of fish red muscle were investigated. Forty to fifty hours after denervation, miniature endplate potentials disappeared abruptly and field stimulation of the nerve within the muscle failed to evoke endplate potentials, indicating that transmission failure occurred at this time. The membrane resistance of the red muscle fibre increased after denervation. Normally innervated fish red muscles do not generate action potentials in response to either nerve or direct muscle stimulation. However, approximately 3 weeks after nerve sectioning, action potentials could be induced in the muscles. The action potential was sodium-dependent, and was sensitive to tetrodotoxin. Actinomycin D injected in the early phase after operation suppressed the induction of the action potential. These results indicate that RNA synthesis is preliminary to the induction of the action potential mechanism, and that this mechanism is under neural control.     

Acute hemodynamics of cardiac sympathetic denervation

IntroductionWe aimed to study the immediate hemodynamic effects of thoracoscopic bilateral cardiac sympathetic denervation (CSD) for recurrent ventricular tachycardia (VT) or VT storm.MethodWe studied a group of 18 adults who underwent bilateral thoracoscopic CSD; the blood pressure (BP) and Heart Rate (HR) were continuously monitored during the surgery and up to 6 h post-operatively.ResultsImmediately on removal of the sympathetic ganglia, the patients had a drop in both the systolic (110 mm Hg to 95.8 mm Hg, p < 0.001) and diastolic BP (69.4 mm Hg to65 mm Hg, p = 0.007) along with a drop in the HR (81.6 bpm to 61.2 bpm, p < 0.001).At 6 h after CSD, the systolic and diastolic BP did not recover significantly, while there was recovery in HR (61.2 bpm to 66 bpm, p = 0.02). There was no significant difference between those with and without left ventricular (LV) systolic dysfunction.ConclusionThe acute hemodynamic changes during the perioperative period of CSD are significant but not serious. Awareness of this is useful for peri-operative management.     

Lysosomes in skeletal muscle following denervation

Summary The in-vivo uptake of exogenously applied horseradish peroxidase and the activities of the lysosomal enzymes acid phosphatase and cathepsin D were studied histochemically and/or biochemically in innervated and 2–14 day-denervated tibialis anterior muscles of the mouse. The biochemically determined uptake of horseradish peroxidase showed a large increase already 4 days after denervation. The activities of the lysosomal enzymes increased in a more gradual fashion, and only cathepsin D showed an increase in activity when expressed as total activity per muscle. Histochemically horseradish peroxidase was found to be localized in muscle fibres in characteristic spindle-shaped segments after denervation. The main increase in the number of such segments per transverse section of the muscle occurred between 3 and 6 days after denervation. In serial sections these segments frequently showed positive staining also for acid phosphatase.It is concluded that exogenously applied horseradish peroxidase is taken up into the lysosomal system, which after denervation becomes organized into characteristic spindle-shaped segments in the muscle fibres. The endocytic activity of muscle fibres increases early after denervation. This is followed by a more gradual increase in activity of lysosomal enzymes and finally by an organization of the lysosomal system into characteristic spindle-shaped segments. The results are compatible with the working hypothesis that increased endocytosis may initiate lysosomal activation in denervated skeletal muscle.     

Skeletal muscle nuclear ATPase under denervation

Denervation of the rabbit gastrocnemius muscle is shown to result after 18 and 72 h in a decrease of Mg2+-, Ca2+-dependent and an increase of Mg+-dependent parts of nuclear ATPase activity, with the total level of the enzyme activity retained. 7 days later the total ATPase activity of nuclei decreases as well as the expense of its EGTA-dependent part. These changes correlate with those in the nuclear Ca total content. Indirect electrostimulation of the denervated muscle increase both the 7g2+-, Ca2+-dependent ATPase activity and the Ca content in nuclei. Tenotomy for 18 h does not change these parameters.     

Induction of rat muscle carbonic anhydrase by denervation demonstrated with immunofluorescence

Immunofluorescence microscopy of carbonic anhydrase III (CA III) was performed on sections of rat anterior tibialis (AT), extensor digitorum longus (EDL) and soleus after denervation. In contralateral control muscles, CAIII was located only in type I fibres whereas following the operation, CAIII was markedly induced in type II fibers of all the muscles, most strikingly in EDL.     

Collateral vessel growth induced by femoral artery ligature is impaired by denervation

Innervation plays an important role in development and remodeling of blood vessels. However, very little is known whether innervation is involved in arteriogenesis. In the present study, we tested the hypothesis that innervation may contribute to the process of arteriogenesis induced by ligature of femoral artery in rat/rabbit hind limb with or without denervation. We found that: (1) angiography showed more collateral vessels in the ligature side than that in ligature plus denervation side; (2) collateral vessels in denervation side was characterized by an inward remodeling; (3) in both collateral vessels (CVs) from only femoral ligature side as well as the ligature plus denervation side, ICAM-1 and VCAM-1 expression was up-regulated but increased VCAM-1 was more evident in the adventitia of collateral vessels of only femoral ligature side; (4) 7 days after surgery, in CVs from the femoral ligature side only, numerous macrophages (RAM11 positive cells) and high cell proliferation ratio (ki67 positive cells) were detected, but they were less in the denervation side. In conclusion, our data demonstrate for the first time that neural regulation is one of the factors that contributes to collateral vessel growth in rat/rabbit hind limb ischemic model by showing collateral vessel growth induced by femoral artery ligature is impaired by denervation.