Search

Proanthocyanidin-A2, a catechic dimer extracted from the bark of Aesculus hippocastanum L., was tested on peripheral nerve regeneration. Reinnervation of EDL and soleus muscles following traumatic nerve damage was investigated in rats by using "in vivo" tension recording technique. Muscle contraction force (twitch and tetanus), the number of motor units and the time course of twitch (time to peak and half relaxation time), were observed. The results obtained do not show that the time course of EDL and soleus muscles reinnervation is different in Proanthocyanidin-A2-treated rats in comparison to control animals. On the contrary, results point out an increase in EDL and soleus muscle mass, both in denervated and in undenervated treated rats compared to corresponding controls. Moreover, consistently with this finding, an increase in their contraction force was found. These data show that Proanthocyanidin-A2 exerts a trophic effect on muscle.

During muscle reinnervation, a transitory phase of polyinnervation occurs. In reinnervated muscles of vitamin E deficient rats, sprouting and polyinnervation are increased with respect to reinnervated controls. In this work, polyinnervation was observed in reinnervated extensor digitorum longus (edl) muscle of rats treated with pharmacological doses of vitamin E. Sciatic nerve was crushed and edl muscle was examined electrophysiologically at 30, 40 and 60 days after denervation. The percentage of polyinnervated cells in controls peaked at 30 days and thus it decreased. In muscles of vitamin E treated rats, the time course of percentage of polyinnervated muscle cells was qualitatively the same, but it was decreased at all times.

Miniature endplate potentials (MEPPs) are regarded as the expression of release of a single quantum of acetylcholine by motor nerve endings in the muscle. Mepp frequency is dependent on the presynaptic mechanism, but MEPP amplitudes and time courses are the result of the characteristics of pre- and postsynaptic structures and of the interaction between them. After post-traumatic reinnervation of skeletal muscles, MEPP frequency increases, reaching slowly normal values. Two groups of male, Sprague Dawley rats were used: in the first group left sciatic nerve was crushed and nerve fibres were allowed to regenerate, whereas the others were regarded as controls. MEPPs were intracellularly recorded in end plates of normal and reinnervated left extensor digitorum longus muscle. MEPPs were sampled and recorded on a personal computer, and, subsequently, amplitude, rise time and half decay time were computed. At early stage after reinnervation, MEPPs showed rise times and decay times longer than normal. Afterwards, we did not find differences between mepp time courses by normal and reinnervated end plates. The possible relationships between the results and changes in acetylcholine receptor number and type, and in acetylcholinesterase activity occurring during denervation and reinnervation are discussed.

During motor nerve regeneration a transitory polyinnervation of muscle cells occurs, which represents a phase of rearrangement of the recovered innervation. Bilobalide, a terpene extrated from Ginkgo biloba leaves, was proposed to affect some aspects of nervous system development and regeneration. In this work, influence of bilobalide on polyinnervation in reinnervated extensor digitorum longus muscle was studied, through electrophysiological and histological techniques. The muscle was denervated crushing the sciatic nerve and it was examined at 1 or 2 months after denervation. The polyinnervated muscle cells in controls reached 24% at 1 month and thus the percentage decreased. In muscles of bilobalide treated rats the number of polyinnervated cells was decreased at both times.

Electrocardiographic changes induced by Labetalol, a drug blocking alpha- and beta-adrenergic receptors, have been studied in 10 anesthetized rats. Authors observed that Labetalol has: 1) slightly negative chronotropic action; 2)slightly negative dromotropic action on both atrio-ventricular and intraventricular conduction; 3) effective antiarrhythmic and alpha-blocking action and, inconstantly, 4) the so-called "intrinsic sympathicomimetic action" (I.S.A.), typical of several beta-blocking drugs.

The effect of Vipera berus venom on shape of human red blood cells and on rouleaux formation has been studied. The venom causes a disk-sphere transformation and causes a complete inhibition of the rouleaux formation.

In the course of their experiments, the Authors did not observe any modifications in the rat electrocardiogram, induced by a 2,5 mg DCA-ajmaline intravenous injection, nor, in particular, any negative bathmotropic action due to it.

From the Authors' observations during this research, there emerges the fact that pindololo does not seem deprived of that cardiodepressive action, which is typical of all beta-blocking drugs.

The effect of Berus Viper's venom on human blood globular resistance with changing incubation conditions has been studied. Particularly venom's concentration (from 200 to 400 microgram/ml of blood), temperature (from 20 degrees C to 37 degrees C) and time (from 1/2h to 2h) have been changed. Time and temperature are important factors in haemolytic process development, instead venom's concentration behave like a factor not significantly haemolysis modifying.

The effect of Vipera berus venom on coagulation of human blood has been studied. PTT and coagulation time according to Quick of normal human plasma kept with Vipera berus venom (400 microgram/ml) for variable times have been misused. The venom has an immediate coagulant and, subsequently, anticoagulant effect.

The activity of some clotting factors of human blood after incubation at 37 degrees C with Vipera berus venom (400 microgram/ml of plasma) has been measured. Factor V, initially, is activated by venom, but rapidly its activity decreases, becoming lower of that of controls and it exhausts oneself almost fully after 2 hours. Changes in the prothrombin and fibrinogen activity by venom action have not been noted.

The aim of this paper is to draw information about influence of human red cell N-acetyl-neuraminic acid and its interaction with Ca++ on membrane itself stability. Then, changes of red cell behavior in reply to osmotic stress with and without Ca++ after treatment with neuraminidase has been studied. We noted that the treatment with neuraminidase causes spontaneous hemolysis (about 9%), independently of medium osmolarity. As regards membrane resistance to osmotic stretching, N-acetyl-neuraminic acid has a destabilizing effect on most erythrocytes whereas its interaction with Ca++ don't influences significantly membrane resistance to osmotic stretching. Nevertheless, in extreme conditions of osmolarity (i.e. when hemolysis of younger red cells occurs), destabilizing effect of N-acetyl-neuraminic acid is no longer observable and, on the contrary, when it interacts with Ca++, it increases the osmotic resistance of red cells.

Electrocardiographic changes induced by Verapamil, drug inducing inhibition of transmembrane movement of calcium into cardiac cells and mobilization of intracellular Ca++, have been studied in 10 anesthetized rats. Authors observed that Verapamil has: 1) negative chronotropic action on SA node; sometimes appears a superior nodal rhythm; 2) inconstantly, negative dromotropic action with prolonged atrioventricular conduction and "period of Luciani-Wenckebach'; 3) effective antiarrhythmic action; 4) no protective action towards peripheric vascular epinephrine effects; 5) remarkable negative inotropic action, whose Authors consider indirect signs the electrocardiographic changes, which indicate severe coronary failure, and the death of 6 rats by acute pulmonary edema.

Ethanol causes the hyperpolarization of the excitable membranes. In the Extensor Digitorum Longus (EDL) muscle of the rat the increase of resting membrane potential is 2-5% and is independent of the concentration of alcohol between 0.2 and 0.4 M, while at higher concentrations the membrane potential falls to levels equal or inferior to the normal potential. We have studied the hyperpolarization action of ethanol on the denervated muscle by crushing the sciatic nerve. Also under these conditions in which, as is known, there is a drop in the resting potential, ethanol causes hyperpolarization, however it is in general greater and it is dependent upon the concentration between 0.2 and 0.8 M.

In these experiments in the rat was studied the action of nicotine, administered intravenously in doses from 20 to 900 gamma/Kg. It was seen that, after the injection of lower doses, in the first phase there is always a more or less conspicuous diminution of the heart rate and a light and fleeting rise of the time of a-v conduction; there follows, after 25-30', a phase in which there is, as already noted, a rise of the heart rate. After higher doses was observed always an increase of the heart rate. Extrasystoles due to the action of nicotine was not observed. Sometime were observed signs of subendocardial damage or of fleeting right bundle-branch block. After a dose of 300 gamma (900 gamma/Kg) was observed a conspicuous and brief inhibition of sinus node activity and of the a-v conduction.

The effect of Berus viper's venom on the osmotic globular resistance of human blood, incubated for a period of 2 hours at 20 degrees C with amounts of venom in the range of 200 to 400 gamma/ml of blood, has been studied. The hemolytic effect occurs to a greater extent at NaCl concentrations higher than 0,60%.

The ethanol changes the quantal spontaneous release of acetylcholine and it affects the reinnervation time course. The effects of ethanol on regenerated nerve endings have been tested. 20 days after crushing sciatic nerve, the m.e.p.p. frequency at the end plate of rat extensor digitorum longus muscle keep in Ringer solution without and with ethanol has been estimated by intracellular recordings. The increase of the m.e.p.p. frequency produced by ethanol is greater in immature, than in normal nerve endings.

We have studied the effects of the fluidizing action of ethanol on motor reinnervation in order to clarify if membrane fluidity changes affect synaptic plasticity and nerve regeneration. Sprague Dawley rats were denervated by crushing the sciatic nerve and subsequently, on the 16th day, the degree of reinnervation of the EDL muscle was observed by electrophysiological technique: in particular an observation was made of the resting potential and the m.e.p.p.s frequency by intracellular recordings in muscle fibers. During the nerve regeneration period, the rats were treated with 3 g of ethanol per kilogram of body weight per day. We have found that ethanol quickens the resting potential recovery but does not affect the m.e.p.p.s frequency.

It is known how noticeable modifications may be induced in the high sulphur content proteins of wool, by enrichment of the diet of sheep with cysteine or sulphur amino acids. It is also well known how the oral ingestion of gelatin significantly increases hair diameter and the degree of hardness of finger and toe nails. To the end of verifying the possible stimulating selective action performed by cystine and gelatin in the keratinization processes of the hairy structures, it was controlled: amino acids content in hair of normal rat after oral ingestion of a controlled quantity of gelatin-cystine added in the diet. The same experiments have been carried out on rats in which the condition of sufference of the hair was induced by means of a biotin-free diet. From the obtained data it seems that gelatin-cystine, added in the diet of normal or suffering rats, helps to modify the cysteine content of the sulphur-rich hair proteins (+ 50% abt.). The diet supplement bring about a considerable increasing of CYS (+ 35%) with a decreasing of GLY (- 15%).

The aim of this research is the study of the modification of synaptic activity caused by ethanol in the rat sciatic nerve-extensor digitorum longus (EDL) muscle preparation. For such a purpose, intracellular recordings have been carried out, keeping the muscle immersed in normal Ringer solution and in Ringer solutions containing ethanol at different concentrations up to 0,8 M. Therefore, the resting potential of muscle cells and the frequency of m.e.p.p.s were measured. Qualitative observations of m.e.p.p.s shape were also carried out. Ethanol increases the frequency of m.e.p.p.s in the rat sciatic nerve - EDL muscle preparation. The logarithm of relative frequency (frequency in Ringer solution with ethanol/frequency in normal Ringer solution) is linear with respect to the concentration of ethanol, with a slope of 1.44. Furthermore, ethanol increases the amplitude and lengthens the time course of m.e.p.p.s. The muscle cells undergo a hyperpolarization of about 2-3% at the lowest concentrations of ethanol tested.

Ethanol greatly modifies synaptic function and it affects the reinnervation time course. In order to better clarify the effects of ethanol on nerve regeneration, we have observed the recovery of algesthesia and reflex activity in the rat during the treatment with ethanol. For this purpose the posterior leg of Sprague Dawley rats was denervated by crushing the sciatic nerve and the recovery of algesthesia and reflex activity was tested at the level of the metatarsus-falanx articulation of the homolateral paw. During the reinnervation period, the animals were treated daily with ethanol 3 g/Kg of body weight. The recovery of algesthesia and reflex activity comes about in a medio-lateral direction and proceeds linearly. It is completed on the 25th day after the denervation. Ethanol does not cause changes in the time course of algesthesia recovery, however it does cause a slight delay in the recovery of the reflex activity.

Human blood hemolysis in NaCl 0,42% solution at 20 degrees C with different amounts of Berus Viper's venom in the range of 100 to 2000 microgram/ml of blood, has been studied. At these conditions venom's antihemolytic considerable action has been found.

The effect of Vipera berus venom on some feature of human red cell membrane has been studied. The venom causes an inhibition of sedimentation rate and it causes an increase of hematocrit value.