Scorpions trapped in amber: a remarkable window on their evolution over time from the Mesozoic period to present days

This synoptic review aims to bring some general information on fossil scorpions, namely those trapped in amber - fossilized resin - ranging from Lower Cretaceous through the Palaeocene and up to the Miocene. The question to be addressed is how the study of these fossils can be connected with possible present scorpionism problems. A precise knowledge of these ancient lineages provides information about the evolution of extant lineages, including the buthoids, which contain most known noxious species. Among the Arthropods found trapped in amber, scorpions are considered rare. A limited number of elements have been described from the Late Tertiary Dominican and Mexican amber, while the most ancient Tertiary amber from the Baltic region produced more consistent results in the last 30 years, primarily focusing on a single limited lineage. Contrarily, the Cretaceous amber from Myanmar, also called Burmite, has yielded and continues to yield a significant number of results represented by several distinct lineages, which attest to the considerable degree of diversity that existed in the Burmese amber-producing forests. As in my previous similar contributions to this journal, the content of this note is primarily addressed to non-specialists whose research embraces scorpions in various fields such as venom toxins and public health. An overview knowledge of at least some fossil lineages can eventually help to clarify why some extant elements associated with the buthoids represent dangerous species while others are not noxious.(AU)

Back to Tityus serrulatus Lutz & Mello, 1922 (Scorpiones: Buthidae): new comments about an old species

A synopsis on the historical, geographical and ecological aspects related to the most conspicuous scorpion species of the genus Tityus known from Brazil is proposed. Tityus serrulatus Lutz & Mello, 1922 was described precisely one century ago, nevertheless many questions related to its ecological adaptations and geographical expansion remain without a precise response. This species, well known for its infamous reputation of noxious species, is also known for its capacity to reproduce asexually, by parthenogenesis. Although the individuals of a given population are considered clones, a new hypothesis could suggest the occurrence of mutations within isolated individuals, leading to distinct subpopulations that could present better phenotypic performances in ecological habitats distinct from those of the original area of distribution of the species.(AU)

Why does the number of dangerous species of scorpions increase? The particular case of the genus Leiurus Ehrenberg (Buthidae) in Africa

The aim of this contribution is to bring some precise information on the reasons why the number of noxious scorpion species is constantly growing. This fact is directly associated with the zoological research on the domains generally defined as systematics and taxonomy. The classification of any zoological group is in most cases a source of problem for most biologists not directly involved with this almost confidential aspect of the zoological research. Much information has been gathered and published over two centuries on the classification but it is remains poorly accessible and too technical for non-experts. The exposed example could be taken from several groups of scorpions possessing infamous species, but the choice went to the genus Leiurus Ehrenberg, 1828 distributed from North Africa to the Middle East. Maybe this contribution will help to explain why so numerous cases of species misidentification are regularly present in the general literature devoted to scorpion venoms and incidents.(AU)

The coevolution between telson morphology and venom glands in scorpions (Arachnida)

As in previous contributions to the JVATiTD, the aim of this note is to bring some general information on a particular aspect of the scorpion biology. An attempt is made to explain the possible coevolution of telson morphology and venom glands, which took place during several hundred million years and in particular since scorpions migrated from aquatic to terrestrial environments. Three components can be directly associated with predation and defensive behaviours: (1) morphology of the chelae and structure of the chelae fingers granulations; (2) morphology of the metasoma and in particular of the telson; (3) evolution of tegumentary glands in the telson toward different types of venom glands. Since a number of recent contributions already treated some of these aspects, I will limit my comments to the possible evolution of the telson in relation to the evolution of venom glands. As in previous contributions, the content of this article is basically addressed to non-specialists on scorpions whose research embraces scorpions in several fields such as venom toxins and public health.(AU)

Sunflower meal with and without phytase supplementation in diets for silver catfish (Rhamdia quelen) juveniles / Harina de girasol con y sin suplementación de fitasa en dietas para juveniles de bagre (barbudo, Col.; Rhamdia quelen) / Farelo de girassol com e sem suplementação de fitase em dietas para juvenis de jundiá ( Rhamdia quelen)

Abstract Background: The cost of feed in fish farming can exceed 70% of the total costs. Thus, the feed industry have sought to formulate balanced diets including low-cost by-products. Objective: To evaluate sunflower meal as a partial substitute (0, 10, and 20%) for soybean meal, with or without phytase supplementation (1,500 FTU/kg) in isoproteic (27% crude protein (CP)) and isoenergetic diets (3,400 kcal/ED/kg of feed) for silver catfish (Rhamdia quelen) juveniles. Methods: A total of 360 fish (weight: 15.77 ± 0.56 g) were randomly distributed in 24 tanks in a completely randomized design following a factorial scheme (3x2) with 4 replicates. The fish were evaluated on the following variables after 90 days: productive performance, hematological variables, histology of intestinal tissue, bromatological composition of carcass, and composition of bone mineral matter. Results: 20% dietary inclusion of sunflower meal improved weight gain and protein efficiency. No difference was observed in the other treatments and no interactions were observed between the other factors. Conclusion: 20% sunflower meal can be included in the feed of silver catfish as a substitute for soybean meal. Phytase inclusion (1,500 FTU/kg) did not improve the nutritional value of the treatments.

Resumen Antecedentes: El costo de la alimentación en piscicultura pueden superar el 70% del costo total. Las industrias de alimentos para peces han intentado formular dietas balanceadas con subproductos de menor valor en el mercado para minimizar costos. Objetivo: Evaluar la harina de girasol como sucedáneo parcial (0, 10 y 20%) de la torta de soya, suplementada o no con fitasa (1.500 FTU/kg) en dietas isoprotéicas (27% de PB) e isoenergéticas 3400 kcal / ED / kg de ración) para bagre (barbudo, Col.; Rhamdia quelen). Métodos: Los peces, 360 juveniles (15,77 ± 0,56 g), se distribuyeron aleatoriamente en 24 unidades experimentales, en un diseño completamente al azar, en esquema factorial (3x2) y 4 repeticiones. A los 90 días se evaluó: desempeño productivo, variables hematológicas, histología de tejido intestinal y composición bromatológica de la carcasa y de la materia mineral de los huesos. Resultados: La inclusion de 20% de harina de girasol mejoró la ganancia de peso de los peces y la tasa de eficiencia proteica de la ración, sin diferencia para las otras evaluaciones ni interacción entre los demás factores evaluados. Conclusión: La harina de girasol se puede utilizar en un 20% de la ración del bagre (barbudo, Col.) como sucedáneo a la harina de soja. La inclusión de fitasa (1.500 FTU/kg) no mejoró el valor nutritivo de estas raciones.

Resumo Antecedentes: Os custos relativos a alimentação na piscicultura pode ultrapassar 70% do custo final, neste sentido, as indústrias de rações têm procurado formular dietas balanceadas com subprodutos de menor valor de mercado para minimizar estes custos. Objetivo: Esse estudo objetivou avaliar o farelo de girassol como sucedâneo parcial (0, 10 e 20%) do farelo de soja, suplementado ou não com a fitase (1.500 FTU/kg), em dietas isoprotéicas (27% de PB) e isoenergéticas (3400 kcal/ED/kg de ração) para o jundiá (Rhamdia quelen). Métodos: Os peixes, 360 juvenis (15,77 ± 0,56 g) foram distribuídos aleatoriamente em 24 unidades experimentais, num delineamento inteiramente casualizado, em esquema fatorial (3x2) e 4 repetições. Após 90 dias foram avaliados: desempenho produtivo, variáveis hematológicas, histologia de tecido intestinal, composição bromatológica da carcaça e de matéria mineral dos ossos. Resultados: O emprego de 20% de farelo de girassol melhorou o ganho de peso dos peixes e a taxa de eficiência protéica da ração, sem diferença nas outras avaliações, ou para a interação entre os demais fatores avaliados. Conclusão: Pode-se concluir que o farelo de girassol pode ser utilizado em 20% da ração do jundiá, como sucedâneo ao farelo de soja e, que a inclusão de fitase (1,500 FTU/kg) não melhorou o valor nutritivo destas rações.

Extension of the geographic distribution of Plecturocebus baptista (Pitheciidae, Primates) and a possible hybrid zone with Plecturocebus hoffmannsi: evolutionary and conservation implications

Titi monkeys (family Pitheciidae) are Neotropical primates highly diversified in morphology, ecology and genetics, with a wide geographic distribution, including the Amazon, Atlantic Forest, Cerrado, Pantanal and Caatinga. This diversity, together with knowledge gaps, generates uncertainties in titi monkey taxonomy and distribution. An example is Plecturocebus baptista, with only 14 occurrence records and an ill-defined distribution based on untested geographical barriers. Here, we report the occurrence of this species at a new locality outside its known range, across the Paraná-Urariá River, which was considered a distributional limit for the species. The new record implies an overlap of P. baptista with the range of P. hoffmannsi. We document the sighting of an apparent hybrid animal. Our observations suggest that i) the distribution of P. baptista needs to be reviewed, and ii) the evolutionary relationships between P. baptista and P. hoffmannsi may be more complex than previously assumed. Since both species share contiguous areas of potential hybridization, we question whether the two species arose via allopatric speciation. (AU)

Antiplasmodial evaluation of Anacardium occidentale and alkyl-phenols

Abstract The ethanol crude extract from cashew (Anacardium occidentale L. Anacardiaceae) displayed significant antiplasmodial activity (IC50 0.577 µg/ml). Liquid chromatography-high resolution Mass spectrometry analysis was performed to identify the main compounds existing in the ethanol extract. The occurrence of anacardic acids, cardols, and 2-methylcardols derivatives was confirmed in the extract. The IC50 obtained, when the main isolated compounds were evaluated in Plasmodium falciparum D6 strain, ranged from 5.39 µM to >100 µM. Tested here for the first time, the data showed that cardol triene 1 (IC50 = 5.69 µM) and 2-methylcardol triene 4 (IC50 = 5.39 µM) demonstrated good antimalarial activity. In conclusion, Anacardium occidentale nuts presented relevant biological potential, and further studies should be considered.

Effect of heat stress on enzymatic and non-enzymatic antioxidants in Brassica rapa

Aim: Heat stress due to increase in global temperature is posing a serious threat to the agricultural sector in many parts of the world. The present investigation was, therefore, undertaken to study the mechanism of thermos-tolerance in four-day-old seedlings of Brassica rapa (44 genotypes) on the basis of various enzymatic and non-enzymatic antioxidants. The information gathered through the present investigation can pave way for imparting tolerance to Brassica genotypes by altering enzyme activities through genetic engineering interventions. Methodology: A total of 44 genotypes were evaluated for survival percentage, electrolyte leakage and chlorophyll content under heat stress conditions. Seedlings were characterized by membrane lipid peroxidation and antioxidants viz. peroxidase and catalase activities, proline and glutathione. Heat stress conditions were created by exposing four-day-old seedlings to 45ºC for 4.5 hr. Out of 44 genotypes, four genotypes (JMT-04-03, TL-2035, TL-98-01 and PBT-37) were thermos-tolerant. Tolerant genotypes registered survival greater than 65%, moderately tolerant between 35-65% and susceptible less than 35%. Results: Among various parameters studied, under heat stress, a significant increase in electrolyte leakage, lipid peroxidation, peroxidase activity, glutathione and proline content was observed in comparison to control seedlings, whereas a decline in CAT activity and chlorophyll content was recorded. Interpretation: Biochemical changes observed in the activities and contents of various parameters studied could be linked with enhanced tolerance to heat stress damage in Brassica rapa which could further be used as a marker for screening against heat stress

Hypericum perforatum chronic treatment affects cognitive parameters and brain neurotrophic factor levels

Objective: To evaluate the effects of Hypericum perforatum (hypericum) on cognitive behavior and neurotrophic factor levels in the brain of male and female rats. Methods: Male and female Wistar rats were treated with hypericum or water during 28 days by gavage. The animals were then subjected to the open-field test, novel object recognition and step-down inhibitory avoidance test. Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and glial cell-line derived neurotrophic factor (GDNF) levels were evaluated in the hippocampus and frontal cortex. Results: Hypericum impaired the acquisition of short- and long-term aversive memory in male rats, evaluated in the inhibitory avoidance test. Female rats had no immediate memory acquisition and decreased short-term memory acquisition in the inhibitory avoidance test. Hypericum also decreased the recognition index of male rats in the object recognition test. Female rats did not recognize the new object in either the short-term or the long-term memory tasks. Hypericum decreased BDNF in the hippocampus of male and female rats. Hypericum also decreased NGF in the hippocampus of female rats. Conclusions: The long-term administration of hypericum appears to cause significant cognitive impairment in rats, possibly through a reduction in the levels of neurotrophic factors. This effect was more expressive in females than in males.

Leiomiomatosis intravascular gigante con extensión a cavidades cardíacas / Giant intravascular leiomyomatosis intravascular with extension to the cardiac cavities

Resumen Se presenta el caso de inusual crecimiento intracardíaco de leiomiomatosis intravascular gigante en una mujer de 38 años, en quien durante evaluación prequirúrgica de cirugía abdominal se documentó de manera incidental una masa en cavidades cardiacas derechas. Dada su presentación infrecuente y las dificultades en el abordaje diagnóstico y terapéutico, se realiza posterior revisión de la literatura.

Abstract The case is presented of an unusual intracardiac growth of a giant intravascular leiomyomatosis in a 38 year-old woman. During a pre-surgical evaluation for abdominal surgery, the incidental finding of a mass in the right cardiac cavities was noted. Given its uncommon presentation and the difficulties in the diagnostic and therapeutic approach, a subsequent review of the literature was performed.

Scorpions and life-history strategies: from evolutionary dynamics toward the scorpionism problem

This work aims to contribute to the general information on scorpion reproductive patterns in general including species that can be noxious to humans. Scorpions are unusual among terrestrial arthropods in several of their life-history traits since in many aspects their reproductive strategies are more similar to those of superior vertebrates than to those of arthropods in general. This communication focuses mainly on the aspects concerning embryonic and post-embryonic developments since these are quite peculiar in scorpions and can be directly connected to the scorpionism problem. As in previous similar contributions, the content of this communication is addressed mainly to non-specialists whose research embraces scorpions in several fields such as venom toxins and public health. A precise knowledge of reproductive strategies presented by several scorpion groups and, in particular, those of dangerous species may prove to be a useful tool in the interpretation of results dealing with scorpionism, and also lead to a better treatment of the problems caused by infamous scorpions.

Scorpions and life-history strategies: from evolutionary dynamics toward the scorpionism problem

This work aims to contribute to the general information on scorpion reproductive patterns in general including species that can be noxious to humans. Scorpions are unusual among terrestrial arthropods in several of their life-history traits since in many aspects their reproductive strategies are more similar to those of superior vertebrates than to those of arthropods in general. This communication focuses mainly on the aspects concerning embryonic and post-embryonic developments since these are quite peculiar in scorpions and can be directly connected to the scorpionism problem. As in previous similar contributions, the content of this communication is addressed mainly to non-specialists whose research embraces scorpions in several fields such as venom toxins and public health. A precise knowledge of reproductive strategies presented by several scorpion groups and, in particular, those of dangerous species may prove to be a useful tool in the interpretation of results dealing with scorpionism, and also lead to a better treatment of the problems caused by infamous scorpions.(AU)

The evolution and distribution of noxious species of scorpions (Arachnida: Scorpiones)

This contribution attempts to bring some general information on the evolution and, in particular, on the geographic distribution of scorpion species noxious to humans. Since 95% of the scorpions incidents are generated by specimens of the family Buthidae C. L. Koch, the analysis will be limited to this familial group. As in previous similar contributions, the content of this work is mostly addressed to non-specialists whose research embraces scorpions in several fields such as venom toxins and public health. Only in recent years, efforts have been made to create better links between 'academic scorpion experts' and other academic non-specialists who use scorpions in their research. Even if a larger progress can yet be expected from such exchanges, crossed information proved to be useful in most fields of scorpion studies. Since the taxonomy of scorpions is complex, misidentifications and even more serious errors concerning scorpion classification/ identification are often present in the general literature. Consequently, a precise knowledge of the distribution patterns presented by many scorpion groups and, in particular, those of infamous species, proves to be a key point in the interpretation of final results, leading to a better treatment of the problems caused by infamous scorpion species.(AU)

Índices e dimensões ecocardiográficas de equinos da raça Mangalarga Marchador / Echocardiographic indexes and dimension in horses of the Mangalarga Marchador breed

Com o objetivo de determinar os valores de referência ecocardiográficos de equinos da raça Mangalarga Marchador, foram avaliados 80 equinos desta raça, machos e fêmeas, com 1,6 a 16 anos de idade, pesando entre 320 a 500 kg, divididos igualmente em 4 grupos: fêmeas de 1,6 a 4 anos de idade (G1), fêmeas com mais de 4 anos de idade (G2), machos de 1,6 a 4 anos de idade (G3), machos com mais de 4 anos de idade (G4). A avaliação constou de exame ecocardiográfico mono e bidimensional, tendo sido realizados através da janela cardíaca direita, nos modos B e M: DIVDs, DIVDd, SIVs, SIVd, DIVEs, DIVEd, PLVEs, PLVEd, Aod, FS%, EF%, AEs, Aod, Aes/ Aod, ponto E-S. Através da janela cardíaca esquerda nos modos B e M: DIVEs, DIVEd, FS%, EF%, AEs. Foram observadas diferenças estatísticas entre as médias dos quatro grupos dos seguintes parâmetros: Aod, AEs, DIVDs, DIVDd, SIVs, SIVd, DIVEs, DIVEd, PLVEs, PLVEd, Vs, Vd e correlações estatísticas positivas entre Aod, AEs, SIVs, SIVd, PLVEs, PLVEd, Vd e a idade, entreAod, AEs, SIVs, SIVd, DIVEd, PLVEs, AEs/Aod e o peso e o perímetro torácico e entre Aod, AEs, SIVs, SIVd, DIVEs, PLVEs, Vd e a altura da cernelha. Houve influência tanto do sexo como da faixa etária sobre os valores de referência para equinos da raça Mangalarga Marchador, tendo os machos acima de 4 anos apresentados valores de medidas ventriculares maiores. O peso, altura e idade dos animais influenciaram da mesma forma os resultados, estando todos relacionados positivamente ao tamanho da estrutura cardíaca.(AU)

Aiming to establish the echocardiographic reference values of cardiac dimensions and indexes in horses of the Mangalarga Marchador breed, 80 horses, weighing 320 to 500 kg, that were divided in four group by gender and age, as follows: 1.6 to 4-year-old females (G1), more than 4-year-old females (G2), 1.6 to 4-year-old males (G3) and above 4-year-old males (G4), were evaluated by standardized technique. The evaluation consisted of B-mode and guided M-mode echocardiography, by which the following measurements were made: from the right cardiac window, by B- and M-mode: systolic and diastolic RVID, IVS, LVID, LVFW, Aod, FS% and EF%, by B-mode: Las, Aod, and Las/Aod, by M-mode: S-E point, from left cardiac window, by B- and M-mode: LVIDs, LVIDd, FS% and EF% and by B-mode: Las. There were statistic differences between means of the four groups for the following parameters: Aod, Las, RVIDs, RVIDd, IVSs, IVSd, LVIDs, LVIDd, LVFWs, LVFWd, Vs, Vd. There were statistic correlations between Aod, Las, IVSs, IVSd, LVFWs, LVFWd, Vd and age; Aod, Las, IVs, IVSd, LVIDd, LVFWs, Las/Aod and bodyweight and thoracic perimeter; and Aod, LAs, IVSs, IVSd, LVIDs, LVFWs, Vd and height. Sex and age group influenced the reference values for the Mangalarga Marchador horses; males above 4 years presented higher ventricular measurement values. Height, weight and age of the horses influenced in the same way the results, all being positively related to the size of the cardiac structure.(AU)

Antibacterial activity of (-)-cubebin isolated from Piper cubeba and its semisynthetic derivatives against microorganisms that cause endodontic infections

Abstract Recent publications have highlighted the numerous biological activities attributed to the lignan (-)-cubebin (1), Piper cubeba L. f., Piperaceae, and ongoing studies have focused on its structural optimization, in order to obtain derivatives with greater pharmacological potential. The aim of this study was the obtainment of (1), its semisynthetic derivatives and evaluation of antibacterial activity. The extract of the seeds of P. cubeba was chromatographed, subjected to recrystallization and was analyzed by HPLC and spectrometric techniques. It was used for the synthesis of: (-)-O-methylcubebin (2), (-)-O-benzylcubebin (3), (-)-O-acetylcubebin (4), (-)-O-(N, N-dimethylamino-ethyl)-cubebin (5), (-)-hinokinin (6) and (-)-6.6'-dinitrohinokinin (7). The evaluation of the antibacterial activity has been done by broth microdilution technique for determination of the minimum inhibitory concentration and the minimum bactericidal concentration against Porphyromonas gingivalis, Prevotella nigrescens, Actinomyces naeslundii, Bacteroides fragilis and Fusobacterium nucleatum. It was possible to make an analysis regarding the relationship between structure and antimicrobial activity of derivatives against microorganisms that cause endodontic infections. The most promising were minimum inhibitory concentration =50 µg/ml against P. gingivalis by (2) and (3), and minimum inhibitory concentration =100 µg/ml against B. fragilis by (6). Cytotoxicity assays demonstrated that (1) and its derivatives do not display toxicity.

Effects of (-)-6,6'-dinitrohinokinin on adult worms of Schistosoma mansoni: a proteomic analyses

Abstract Schistosomiasis, a chronic disease that affects million people worldwide, is caused by trematode flukes of the genus Schistosoma. The lack of an anti-schistosomiasis vaccine and massive monotherapy with praziquantel reinforces the need for search and development of new therapeutic drugs. Recently, we demonstrated that the essential oil of Piper cubeba L., Piperaceae, and their derivative dibenzylbutyrolactolic (-)-6,6'-dinitrohinokinin, presents in vitro and in vivo activities against Schistosoma mansoni. Here, we identified changes in the protein expression after exposure to dibenzylbutyrolactolic (-)-6,6'-dinitrohinokinin. We applied two-dimensional gel electrophoresis (2-DE) to S. mansoni soluble protein extracts and observed at least 38 spots to be affected by dibenzylbutyrolactolic (-)-6,6'-dinitrohinokinin. We further identified 25 differentially expressed proteins by mass spectrometry. Enrichment for biological processes and predictive analyses of protein-protein interactions suggest that dibenzylbutyrolactolic (-)-6,6'-dinitrohinokinin targets proteins involved mainly in metabolic processes, especially carbohydrate metabolism. In summary, this study provides an interesting approach to understand the anti-parasitic activity of semi-synthetic (-)-6,6'-dinitrohinokinin a derivative compound from lignan and for the development of new therapy strategies.

Scorpion incidents, misidentification cases and possible implications for the final interpretation of results

The aim of this contribution is to bring general information on the classification and in particular on the specific identification of scorpion species dangerous to humans. Several generic groups are taken into consideration, but the Neotropical genus Tityus C. L. Koch, 1836 is used as a major example. The content of this paper is mostly addressed to non-specialists whose research embraces scorpions in several fields such as venom toxins and public health. Although efforts have been made in the last 20 years to create better links between 'true scorpion experts' and non-specialists who use scorpions in their research, such exchanges had never led to a consensus among those different branches of biological and medical research. Consequently, many cases of species misidentification and even more serious errors concerning scorpion classification/identification are often present in the specialized literature. In conclusion, it is suggested here that the frequent cases of misidentification observed in several reports may induce mistakes in the final interpretation of results, leading only to more inefficacity in the treatment of problems caused by infamous scorpion species.(AU)

Scorpion incidents, misidentification cases and possible implications for the final interpretation of results

The aim of this contribution is to bring general information on the classification and in particular on the specific identification of scorpion species dangerous to humans. Several generic groups are taken into consideration, but the Neotropical genus Tityus C. L. Koch, 1836 is used as a major example. The content of this paper is mostly addressed to non-specialists whose research embraces scorpions in several fields such as venom toxins and public health. Although efforts have been made in the last 20 years to create better links between true scorpion experts and non-specialists who use scorpions in their research, such exchanges had never led to a consensus among those different branches of biological and medical research. Consequently, many cases of species misidentification and even more serious errors concerning scorpion classification/identification are often present in the specialized literature. In conclusion, it is suggested here that the frequent cases of misidentification observed in several reports may induce mistakes in the final interpretation of results, leading only to more inefficacity in the treatment of problems caused by infamous scorpion species.

Influência da altitude sobre parâmetros eletrocardiográficos, obtidos por meio do uso do "Holter" em cavalos de enduro em diferentes níveis de condicionamento físico / Influence of altitude on electrocardiographic parameters by means of the Holter system utilization in endurance horses in different levels of physical conditioning

O presente trabalho teve por objetivo o estudo da influência da altitude sobre os parâmetros eletrocardiográficos obtidos por meio do uso do Holter em 40 cavalos das raças Árabe e Cruza Árabe, em diferentes níveis de condicionamento físico, realizando treinamento em trilhas de 15 km de extensão com velocidade média de 15km/h e variando entre o nível do mar até 1700m de altitude. O monitoramento eletrocardiográfico foi obtido por eletrocardiografia padrão em repouso antes do exercício e por eletrocardiografia dinâmica, com o uso do Holter, durante o exercício e na recuperação pós-exercício. Os animais apresentaram ritmo sinusal com período médio gravado para taquicardia sinusal (32%) e bradicardia sinusal (14%). Entre as arritmias observadas estão o bloqueio atrioventricular de primeiro grau (20%) e o bloqueio atrioventricular de segundo grau (5%). As arritmias ectópicas supraventriculares foram observadas em dois animais e somente um animal apresentou arritmia ventricular. O número de assistolias foi maior em animais menos condicionados. As frequências cardíacas médias e máximas sofreram efeito da altitude com valores maiores em altitude elevada.(AU)

The aim of this paper was to study the influence of altitude on electrocardiographic parameters by means of the Holter system in 40 Arabian and Arabian crossbred horses, at different levels of physical conditioning, during training in trails of 15 km extension with mean speed of 15 km/h, and altitude varying from sea level to 1700m high. The electrocardiographic monitoring was obtained by standard electrocardiography at rest before exercise, and by dynamic electrocardiography with the Holter system applied during exercise and in post-exercise recovery. The animals presented sinusal rhythm, with a mean registered period for sinusal tachycardia of 32%, and 14% for sinusal bradycardia. Among the arrhythmias there was first-degree atrioventricular block (20%) and second-degree atrioventricular block (5%). Supraventricular ectopic arrhythmias were observed in two horses and only one showed ventricular arrhythmia. The number of asystoles was greater in less conditioned horses. Mean and maximal heart rates were influenced by altitude, with higher values in higher altitudes.(AU)