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BACKGROUND: Canine embryo cryopreservation and subsequent transfer are relevant in the use of reproductive technologies. OBJECTIVE: The purpose of this study is the identification and quantification of the gene expression BAX and Bcl2, AQP3, Na+/K+ ATPase alpha-1 and beta-1 and LIFr in canine embryos obtained in vivo and after freezing. MATERIALS AND METHODS: For the collection of embryos, the bitches were identified at pro-estrous until the detection of 80-90% superficial cells. After that, they were artificially inseminated with fresh semen. The embryos were collected after ovariohysterectomy. RNA was extracted and amplified, and embryos were randomly distributed into fresh (Fr) and frozen/thawed (Ft) groups. RESULTS: Eighteen blastocysts were collected from three bitches. Genes BAX, AQP3 and LIFr did not differ among the studied groups. CONCLUSION: We suggest, through these results, that the genes BAX, Bcl2, AQP3, Na + / K + ATPase alpha-1 and beta-1 and LIFr were expressed in canine blastocysts collected in vivo and after slow freezing cryopreservation.

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Objetivou-se determinar a validade, a confiabilidade e a sensibilidade do indicador de dor crônica de Helsinki (IDCH) em português, além de estabelecer correlação entre a plataforma de pressão em cães com displasia coxofemoral (DCF). O questionário foi preenchido por tutores de 40 animais com DCF e por 16 tutores de cães saudáveis. Os animais com DCF foram tratados com carprofeno 4,4mg/kg (GT= 21) ou placebo (GP= 19), administrados uma vez ao dia, durante quatro semanas. A avaliação consistiu no preenchimento do questionário (IDCH), na escala analógica visual de dor (EAVdor) e na escala analógica visual de locomoção (EAVloc) com duas semanas (A1) e imediatamente antes do tratamento (A2), duas (S2) e quatro (S4) semanas de tratamento e após duas semanas do término do tratamento (S6). A consistência interna dos dados foi considerada excelente (alfa de Cronbach = 0,89). Houve correlação moderada entre o IDCH e a EAVdor e boa entre o IDCH e a EAVloc, porém não houve diferença entre o grupo tratado com carprofeno e placebo no IDCH. Não houve correlação entre os dados da plataforma de pressão e o IDCH. O questionário apresentou validade de constructo, critério e fidedignidade e pode-se empregá-lo em países de língua portuguesa em cães com osteoartrite.(AU)

We aimed to determine validity, reliability, and sensitivity of Helsinki's chronic pain index (HCPI) and stablish a correlation between HCPI in dogs with hip dysplasia (HD) using pressure sensitive walkway. Forty-owners of dogs with HD and 16 owners of health dogs filled a questionnaire. Dogs with HD were treated with carprofen 4.4mg/kg (GT n= 21) or with placebo (GP n= 19), both were administered once a day for 4 weeks. Evaluation was performed by the owners using the questionnaire (HCPI), the Visual Analogue Scale for pain (VASpain) and the VAS for locomotion (VASloc). The evaluation was performed 2 weeks before the treatment began (A1), immediately after treatment (A2), two (S2), four (S4) and two weeks after the end of treatment (S6) and the lameness was evaluated by pressure sensitive walkway. The internal consistency of the data was considered excellent (Cronbach´α coefficient= 0.89). There was a moderate correlation between the HCPI and VASpain. For VASloc the correlation was good. However, there was no difference between treatments, indicating low sensibility. No correlation was observed between pressure sensitive walkway and HCPI. We concluded that the questionnaire has construct and criterion validity, reliability and can be applied in dogs with osteoarthritis in Portuguese-speaking countries.(AU)

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The cryosurgery is a very useful therapy for the treatment of a variety of neoplastic and non-neoplastic processes. Nevertheless, it is still poorly described as an option for the treatment of specific cutaneous neoplasms, such as squamous cell carcinoma. The purpose of the present study was to analyze the clinical response of cryosurgery for the treatment of squamous cell carcinoma in cats. For this 13 squamous cell carcinoma lesions were selected in 11 cats, diagnosed through citopathological and/or histopathological examinations. The lesions were frozen using liquid nitrogen spray, and the evaluations were performed in the moment of freeze and approximately every 15 days until the wound was completely healed. The response of cryosurgery was considered complete with tumoral remission on 38.5% of the cats, and partial on 46.1%. The main complications included crusting and nostril stenosis. The presented results suggested that cryosurgery is effective and may be a viable option for the treatment of squamous cell carcinoma in cats. The effectiveness of the therapy; however, depends on the correct selection of the candidates for cryosurgery based on the lesion size, and the attendance to some criteria, such as the freezing time and post-operative care.(AU)

A criocirurgia tem se mostrado uma terapia de grande auxílio no tratamento de uma variedade de processos neoplásicos e não neoplásicos. Apesar disso, ainda é pouco descrita a utilização da criocirurgia como opção de tratamento de neoplasias cutâneas específicas, como o carcinoma de células escamosas. Objetivou-se com o presente estudo analisar a resposta clínica da criocirurgia para o tratamento do carcinoma de células escamosas em gatos. Para isso, foram selecionadas 13 lesões do tipo carcinoma de células escamosas em 11 gatos, diagnosticadas por meio de análise citopatológica e/ou histopatológica. As lesões foram congeladas por meio de nitrogênio líquido na forma de spray, e as avaliações realizadas no momento do congelamento e aproximadamente a cada 15 dias, até a completa cicatrização da ferida. A resposta da criocirurgia foi considerada completa, com remissão tumoral em 38,5% dos gatos e parcial em 46,1% destes. As principais complicações verificadas incluíram a formação de crostas e estenose de narina. Os resultados apresentados no presente estudo sugerem que a criocirurgia é efetiva e pode ser uma opção viável para o tratamento do carcinoma de células escamosas em gatos. O sucesso do tratamento, entretanto, depende da correta seleção dos candidatos à técnica quanto ao tamanho da lesão, e do atendimento a alguns critérios, como o tempo de congelamento e os cuidados pós-operatórios.(AU)

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The mechanism of doxorubicin (DOX)-induced cardiotoxicity remains controversial. Wistar rats (n = 66) received DOX injections intraperitoneally and were randomly assigned to 2 experimental protocols: (1) rats were killed before (-24 h, n = 8) and 24 h after (+24 h, n = 8) a single dose of DOX (4 mg/kg body weight) to determine the DOX acute effect and (2) rats (n = 58) received 4 injections of DOX (4 mg/kg body weight/week) and were killed before the first injection (M0) and 1 week after each injection (M1, M2, M3, and M4) to determine the chronological effects. Animals used at M0 (n = 8) were also used at moment -24 h of acute study. Cardiac total antioxidant performance (TAP), DNA damage, and morphology analyses were carried out at each time point. Single dose of DOX was associated with increased cardiac disarrangement, necrosis, and DNA damage (strand breaks (SBs) and oxidized pyrimidines) and decreased TAP. The chronological study showed an effect of a cumulative dose on body weight (R = -0.99, p = 0.011), necrosis (R = 1.00, p = 0.004), TAP (R = 0.95, p = 0.049), and DNA SBs (R = -0.95, p = 0.049). DNA SBs damage was negatively associated with TAP (R = -0.98, p = 0.018), and necrosis (R = -0.97, p = 0.027). Our results suggest that oxidative damage is associated with acute cardiotoxicity induced by a single dose of DOX only. Increased resistance to the oxidative stress is plausible for the multiple dose of DOX. Thus, different mechanisms may be involved in acute toxicity versus chronic toxicity.

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Exercise capacity and quality of life (QOL) are important outcome predictors in patients with systolic heart failure (HF), independent of left ventricular (LV) ejection fraction (LVEF). LV diastolic function has been shown to be a better predictor of aerobic exercise capacity in patients with systolic dysfunction and a New York Heart Association (NYHA) classification ≥ II. We hypothesized that the currently used index of diastolic function E/e' is associated with exercise capacity and QOL, even in optimally treated HF patients with reduced LVEF. This prospective study included 44 consecutive patients aged 55 ± 11 years (27 men and 17 women), with LVEF<0.50 and NYHA functional class I-III, receiving optimal pharmacological treatment and in a stable clinical condition, as shown by the absence of dyspnea exacerbation for at least 3 months. All patients had conventional transthoracic echocardiography and answered the Minnesota Living with HF Questionnaire, followed by the 6-min walk test (6MWT). In a multivariable model with 6MWT as the dependent variable, age and E/e' explained 27% of the walked distance in 6MWT (P=0.002; multivariate regression analysis). No association was found between walk distance and LVEF or mitral annulus systolic velocity. Only normalized left atrium volume, a sensitive index of diastolic function, was associated with decreased QOL. Despite the small number of patients included, this study offers evidence that diastolic function is associated with physical capacity and QOL and should be considered along with ejection fraction in patients with compensated systolic HF.

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Exercise capacity and quality of life (QOL) are important outcome predictors in patients with systolic heart failure (HF), independent of left ventricular (LV) ejection fraction (LVEF). LV diastolic function has been shown to be a better predictor of aerobic exercise capacity in patients with systolic dysfunction and a New York Heart Association (NYHA) classification ≥II. We hypothesized that the currently used index of diastolic function E/e' is associated with exercise capacity and QOL, even in optimally treated HF patients with reduced LVEF. This prospective study included 44 consecutive patients aged 55±11 years (27 men and 17 women), with LVEF<0.50 and NYHA functional class I-III, receiving optimal pharmacological treatment and in a stable clinical condition, as shown by the absence of dyspnea exacerbation for at least 3 months. All patients had conventional transthoracic echocardiography and answered the Minnesota Living with HF Questionnaire, followed by the 6-min walk test (6MWT). In a multivariable model with 6MWT as the dependent variable, age and E/e' explained 27% of the walked distance in 6MWT (P=0.002; multivariate regression analysis). No association was found between walk distance and LVEF or mitral annulus systolic velocity. Only normalized left atrium volume, a sensitive index of diastolic function, was associated with decreased QOL. Despite the small number of patients included, this study offers evidence that diastolic function is associated with physical capacity and QOL and should be considered along with ejection fraction in patients with compensated systolic HF.

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Avaliou-se a confiabilidade e determinou-se a pontuação mínima relacionada à necessidade de intervenção analgésica de uma escala multidimensional para avaliação de dor pós-operatória em gatas submetidas à ovário-histerectomia. Trinta gatas foram filmadas em quatro momentos predeterminados: pré-operatório, pós-operatório antes e depois da analgesia de resgate e às 24 horas após a cirurgia. Quatro observadores, não cientes dos momentos de avaliação, e um observador, considerado padrão-ouro - pesquisador que desenvolveu a escala - , avaliaram os vídeos em ordem aleatória, a partir da aplicação da escala, e determinaram a suficiência ou não de analgesia, baseando-se na experiência clínica. Os vídeos foram reavaliados dois meses após a primeira análise. O grau de concordância entre as avaliações dos diferentes observadores e das avaliações feitas pelo mesmo observador em diferentes ocasiões foi verificado pelo coeficiente de correlação intraclasse, que variou entre bom e muito bom para todos os itens da escala, exceto atividade, atitude e miscelânea de comportamentos que apresentaram confiabilidade moderada. O ponto de corte ótimo (> 7) foi selecionado pela análise descritiva e da curva Receiver Operating Characteristic. Os resultados suportam a confiabilidade em termos de reprodutibilidade e estabilidade e indicam que a terapia analgésica deve ser considerada em pontuações >8.

The aim with this study was to evaluate the reliability, and to establish the minimum score relating to the analgesic intervention of a multidimensional scale for use in assessing postoperative pain in cats undergoing ovariohysterectomy. Thirty cats were video recorded at 4 predetermined moments: prior to surgery, before and after rescue analgesia postoperatively, and 24 hours after surgery. Four observers blind to the times of assessment, and a gold standard observer (researcher who developed the scale) evaluated the video segments in random order using the scale, and determined the adequacy or not of analgesia based on clinical experience. The videos were reassessed two months after the first analysis. The agreement between the assessment of different observers, and the assessment made by the same observer on different occasions has been verified by the intra-class correlation coefficient that ranged from good to very good for all scale items, except activity, attitude and miscellaneous behaviors, which showed moderate reliability. The optimal cutoff point (> 7) was selected based on descriptive analysis and Receiver Operating Characteristic curve. The findings support the reliability in terms of reproducibility and stability, and indicate that analgesic therapy should be considered in scores >8.

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O manejo adequado da dor depende de métodos de avaliação acurados. O objetivo deste estudo foi avaliar a validade e a responsividade de uma escala multidimensional para avaliação de dor pós-operatória em gatas submetidas à ovário-histerectomia. Trinta gatas foram filmadas no período perioperatório em quatro momentos predeterminados: pré-operatório, pós-operatório antes e depois da analgesia de resgate e às 24 horas após o término da cirurgia. Cinco observadores não cientes dos momentos de avaliação e um observador considerado padrão-ouro (pesquisador que desenvolveu a escala) avaliaram os vídeos em ordem aleatória e determinaram os escores de dor dos animais, utilizando a escala a ser validada. A responsividade e a validade de conteúdo e constructo foram estabelecidas pelo aumento e pela redução significativa nos escores de dor, em resposta ao procedimento cirúrgico e à administração de analgesia de resgate, respectivamente, avaliados pelo teste de Wilcoxon (P<0,001). A validade de critério foi atestada pela concordância alta entre as avaliações do padrão-ouro com os demais observadores, analisada pela porcentagem de absoluta concordância e coeficiente Kappa ponderado. Os resultados suportam a validade e a responsividade de uma escala multidimensional para avaliação de dor aguda pós-operatória em gatas submetidas à ovário-histerectomia, quando utilizada por veterinários formados e com experiência clínica.

Adequate pain management depends on accurate assessment methods. The aim of this study was to evaluate the validity and responsiveness of a multidimensional composite scale for use in assessing postoperative pain in cats undergoing ovariohysterectomy. Thirty cats were video recorded in four predetermined moments during the perioperative period: prior to surgery, before and after rescue analgesia postoperatively, and 24 hours after the end of surgery. Five observers blind to the times of assessment, and a gold standard observer (researcher who developed the scale) viewed the video segments in a random order, and the cat's pain scores were registered using the scale to be validated. The content and construct validity, and the responsiveness were established based on significant increase and reduction in the pain scores, in response to surgery and analgesics administration, respectively (Wilcoxon signed rank test, P<0.001). Criterion validity was determined by high agreement between the evaluations of the gold standard with the other observers, assessed by the percentage of absolute agreement and weighted Kappa coefficient. The findings support the validity and the responsiveness of a multidimensional composite scale to assess postoperative acute pain in cats undergoing ovariohysterectomy, when used by veterinarians with clinical experience.

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Desenvolveu-se uma técnica de bloqueio peribulbar comparando-a à técnica de anestesia oftálmica com bloqueio neuromuscular parcial em cães submetidos à facectomia extracapsular. Doze cães, de diferentes raças, foram alocados em dois grupos (G1 e G2) e anestesiados com acepromazina (0,05mg/kg, IV) e propofol (5mg/kg, IV) e mantidos com isofluorano sob ventilação espontânea. Os cães do G1 receberam o bloqueio peribulbar com ropivacaína 0,75 por cento, e os do G2 o bloqueio neuromuscular parcial com brometo de pancurônio (0,01mg/kg, IV). Utilizaram-se, como parâmetros comparativos, escores de posicionamento do globo ocular, controle do reflexo oculocardíaco e pressão intraocular (mmHg). Foi possível propor uma técnica eficaz para cães baseando-se na técnica de bloqueio peribulbar posterior realizada no homem. Em ambos os grupos, o globo ocular permaneceu centralizado. Não ocorreram alterações eletrocardiográficas atribuídas ao reflexo oculocardíaco. Houve redução significativa da pressão intraocular em G1 após o bloqueio (10,7±0,6 e 14,7±0,6). Conclui-se que o bloqueio peribulbar proporcionou condições cirúrgicas apropriadas para a realização da facectomia, com a vantagem de promover bloqueio sensitivo do olho.

A peribulbar block technique was developed and its clinical efficacy was compared with neuromuscular blockade in dogs undergoing cataract surgery. Twelve dogs of different breeds were randomly and equally allocated in two groups. After given acepromazine (0.05mg/kg, IV), anesthesia was induced with propofol (5mg/kg, IV) and maintained with isoflurane in oxygen during spontaneous breathing. A peribulbar block with 0.75 percent ropivacaine was performed in G1 dogs while partial neuromuscular blockade with pancuronium (0.01mg/kg IV) was provided in G2 dogs. Globe position scores, oculocardiac reflex, and intra-ocular pressure (mmHg) were evaluated at pre-defined intervals during surgery. Peribulbar blocks were successful performed according to posterior peribulbar block described in humans. In both groups, the globe was centralized and globe position scores did not differ between groups. The intra-ocular pressure was significantly lower in G1 after the block (10.7±0.6 vs 14.7±0.6). There were no electrocardiographycal changes attributed to the oculocardiac reflex. In conclusion, satisfactory surgical conditions were provided by the peribulbar block. This technique can be used as an alternative to the use of neuromuscular blocking agents in dogs undergoing cataract surgery, with the advantage of providing analgesia of the eye.

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It has been recently shown that calcium channel blockers might have a protective effect on cardiac fibrogenesis induced by aldosterone. The objective of this study was to evaluate the protective effect of felodipine, a dihydropyridine calcium channel blocker, against heart and kidney damage caused by aldosterone-high sodium intake in uninephrectomized rats. Wistar rats were divided into three groups: CNEP (uninephrectomized + 1% NaCl in the drinking water, N = 9); ALDO (same as CNEP group plus continuous infusion of 0.75 microg/h aldosterone, N = 12); ALDOF (same as ALDO group plus 30 mg*kg(-1)*day(-1) felodipine in the drinking water, N = 10). All results were compared with those of age-matched, untreated rats (CTL group, N = 10). After 6 weeks, tail cuff blood pressure was recorded and the rats were killed for histological analysis. Blood pressure (mmHg) was significantly elevated (P < 0.05) in ALDO (180 +/- 20) and ALDOF (168 +/- 13) compared to CTL (123 +/- 12) and CNEP (134 +/- 13). Heart damage (lesion scores - median and interquartile range) was 7.0 (5.5-8.0) in ALDO and was fully prevented in ALDOF (1.5; 1.0-2.0). Also, left ventricular collagen volume fraction (%) in ALDOF (2.9 +/- 0.5) was similar to CTL (2.9 +/- 0.5) and CNEP (3.4 +/- 0.4) and decreased compared to ALDO (5.1 +/- 1.6). Felodipine partially prevented kidney injury since the damage score for ALDOF (2.0; 2.0-3.0) was significantly decreased compared to ALDO (7.5; 4.0-10.5), although higher than CTL (null score). Felodipine has a protective effect on the myocardium and kidney as evidenced by decreased perivascular inflammation, myocardial necrosis and fibrosis.

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It has been recently shown that calcium channel blockers might have a protective effect on cardiac fibrogenesis induced by aldosterone. The objective of this study was to evaluate the protective effect of felodipine, a dihydropyridine calcium channel blocker, against heart and kidney damage caused by aldosterone-high sodium intake in uninephrectomized rats. Wistar rats were divided into three groups: CNEP (uninephrectomized + 1 percent NaCl in the drinking water, N = 9); ALDO (same as CNEP group plus continuous infusion of 0.75 µg/h aldosterone, N = 12); ALDOF (same as ALDO group plus 30 mg·kg-1·day-1 felodipine in the drinking water, N = 10). All results were compared with those of age-matched, untreated rats (CTL group, N = 10). After 6 weeks, tail cuff blood pressure was recorded and the rats were killed for histological analysis. Blood pressure (mmHg) was significantly elevated (P < 0.05) in ALDO (180 ± 20) and ALDOF (168 ± 13) compared to CTL (123 ± 12) and CNEP (134 ± 13). Heart damage (lesion scores - median and interquartile range) was 7.0 (5.5-8.0) in ALDO and was fully prevented in ALDOF (1.5; 1.0-2.0). Also, left ventricular collagen volume fraction ( percent) in ALDOF (2.9 ± 0.5) was similar to CTL (2.9 ± 0.5) and CNEP (3.4 ± 0.4) and decreased compared to ALDO (5.1 ± 1.6). Felodipine partially prevented kidney injury since the damage score for ALDOF (2.0; 2.0-3.0) was significantly decreased compared to ALDO (7.5; 4.0-10.5), although higher than CTL (null score). Felodipine has a protective effect on the myocardium and kidney as evidenced by decreased perivascular inflammation, myocardial necrosis and fibrosis.

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The anthracyclines constitute a group of drugs widely used for the treatment of a variety of human tumors. However, the development of irreversible cardiotoxicity has limited their use. Anthracycline-induced cardiotoxicity can persist for years with no clinical symptoms. However, its prognosis becomes poor after the development of overt heart failure, possibly even worse than ischemic or idiopathic dilated cardiomyopathies. Due to the successful action of anthracyclines as chemotherapic agents, several strategies have been tried to prevent/attenuate their side effects. Although anthracycline-induced injury appears to be multifactorial, a common denominator among most of the proposed mechanisms is cellular damage mediated by reactive oxygen species. However, it remains controversial as to whether antioxidants can prevent such side effects given that different mechanisms may be involved in acute versus chronic toxicity. The present review applies a multisided approach to the critical evaluation of various hypotheses proposed over the last decade on the role of oxidative stress in cardiotoxicity induced by doxorubicin, the most used anthracycline agent. The clinical diagnosis and treatment is also discussed.

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Estudaram-se os efeitos do sevofluorano sobre a freqüência cardíaca nos fetos de cadelas no terço final de gestação, mediante a mensuração da freqüência cardíaca fetal com a utilização do ultra-som. Nove cadelas, sem raça definida, entre um e cinco anos de idade, com aproximadamente 45 dias de gestação, foram anestesiadas com acepromazina (0,05mg/kg, IV), propofol (5mg/kg, IV) e sevofluorano. O monitoramento da freqüência cardíaca fetal foi realizado antes da medicação pré-anestésica (M0), 15 minutos após a intubação traqueal (M1), aos 30 minutos (M2) e 60 minutos (M3) do período de manutenção anestésica. A pressão arterial sistólica (PAS), média (PAM) e diastólica (PAD) foram obtidas pelo método não invasivo, sendo a PAM avaliada também pelo método invasivo. Por meio do monitoramento da freqüência cardíaca fetal média não se observou diferença significativa entre M0, M1 e M2, e verificou-se elevação apenas aos 60 minutos da manutenção anestésica (M3) em relação ao M0, porém sem significado clínico. O protocolo anestésico provocou diminuição significativa da pressão sangüínea arterial materna sem alterar, porém a freqüência cardíaca dos fetos.

The effect of sevoflurane on fetal heart rate of 45-day fetuses was investigated through monitoring fetal heart rate by ultrasonographic evaluation in nine adult bitches aging from 1 to 5-year-old. After sedation with acepromazine (0.05mg/kg, IV), the anesthetic induction was accomplished using propofol (5mg/kg, IV) and the maintenance was kept with sevoflurane. The fetal heart rate was measured before sedation (M0), 15 minutes after endotracheal intubation (M1), at 30 (M2) and 60 minutes (M3) from the beginning of general anesthesia. The systolic, diastolic and mean blood pressures were obtained by indirect techniques, while mean blood pressure were also obtained by direct technique. The measure of fetal heart rate did not show any difference between M0, M1 and M2, but there was a remarkable increase in the last moment of the study (M3) comparing to M0, however without clinical relevance. The anesthetic protocol employing acepromazine, propofol and sevoflurane in 45-day pregnancy bitches decreased their arterial blood pressure without affecting the fetal heart rate.

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Several indexes of myocardial contractility have been proposed to assess ventricular function in the isovolumetrically beating isolated heart. However, the conclusions reached on the basis of these indexes may be influenced by ventricular geometry rather than contractility itself. The objective of the present study was to assess the performance of widely used contractility indexes in the isovolumetrically beating isolated heart in two experimental models of hypertrophy, the spontaneously hypertensive rat (SHR) and infrarenal aortocava fistula. Compared to normotensive controls (N = 8), SHRs with concentric hypertrophy (N = 10) presented increased maximum rate of ventricular pressure rise (3875 ± 526 vs 2555 ± 359 mmHg/s, P < 0.05) and peak of isovolumetric pressure (187 ± 11 vs 152 ± 11 mmHg, P < 0.05), and decreased developed stress (123 ± 20 vs 152 ± 26 g/cm², P < 0.05) and slope of stress-strain relationship (4.9 ± 0.42 vs 6.6 ± 0.77 g/cm²/ percent). Compared with controls (N = 11), rats with volume overload-induced eccentric hypertrophy (N = 16) presented increased developed stress (157 ± 38 vs 124 ± 22 g/cm², P < 0.05) and slope of stress-strain relationship (9 ± 2 vs 7 ± 1 g/cm²/ percent, P < 0.05), and decreased maximum rate of ventricular pressure rise(2746 ± 382 vs 3319 ± 352 mmHg, P < 0.05) and peak of isovolumetric pressure (115 ± 14 vs 165 ± 13 mmHg/s, P < 0.05). The results suggested that indexes of myocardial contractility used in experimental studies may present opposite results in the same heart and may be influenced by ventricular geometry. We concluded that several indexes should be taken into account for proper evaluation of contractile state, in the isovolumetrically beating isolated heart.

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Several indexes of myocardial contractility have been proposed to assess ventricular function in the isovolumetrically beating isolated heart. However, the conclusions reached on the basis of these indexes may be influenced by ventricular geometry rather than contractility itself. The objective of the present study was to assess the performance of widely used contractility indexes in the isovolumetrically beating isolated heart in two experimental models of hypertrophy, the spontaneously hypertensive rat (SHR) and infrarenal aortocava fistula. Compared to normotensive controls (N = 8), SHRs with concentric hypertrophy (N = 10) presented increased maximum rate of ventricular pressure rise (3875 +/- 526 vs 2555 +/- 359 mmHg/s, P < 0.05) and peak of isovolumetric pressure (187 +/- 11 vs 152 +/- 11 mmHg, P < 0.05), and decreased developed stress (123 +/- 20 vs 152 +/- 26 g/cm(2), P < 0.05) and slope of stress-strain relationship (4.9 +/- 0.42 vs 6.6 +/- 0.77 g/cm(2)/%). Compared with controls (N = 11), rats with volume overload-induced eccentric hypertrophy (N = 16) presented increased developed stress (157 +/- 38 vs 124 +/- 22 g/cm(2), P < 0.05) and slope of stress-strain relationship (9 +/- 2 vs 7 +/- 1 g/cm(2)/%, P < 0.05), and decreased maximum rate of ventricular pressure rise(2746 +/- 382 vs 3319 +/- 352 mmHg, P < 0.05) and peak of isovolumetric pressure (115 +/- 14 vs 165 +/- 13 mmHg/s, P < 0.05). The results suggested that indexes of myocardial contractility used in experimental studies may present opposite results in the same heart and may be influenced by ventricular geometry. We concluded that several indexes should be taken into account for proper evaluation of contractile state, in the isovolumetrically beating isolated heart.

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Cardiac structures, function, and myocardial contractility are affected by food restriction (FR). There are few experiments associating undernutrition with hypertension. The aim of the present study was to analyze the effects of FR on the cardiac response to hypertension in a genetic model of hypertension, the spontaneously hypertensive rat (SHR). Five-month-old SHR were fed a control or a calorie-restricted diet for 90 days. Global left ventricle (LV) systolic function was evaluated in vivo by transthoracic echocardiogram and myocardial contractility and diastolic function were assessed in vitro in an isovolumetrically beating isolated heart (Langendorff preparation). FR reduced LV systolic function (control (mean +/- SD): 58.9 +/- 8.2; FR: 50.8 +/- 4.8%, N = 14, P < 0.05). Myocardial contractility was preserved when assessed by the +dP/dt (control: 3493 +/- 379; FR: 3555 +/- 211 mmHg/s, P > 0.05), and developed pressure (in vitro) at diastolic pressure of zero (control: 152 +/- 16; FR: 149 +/- 15 mmHg, N = 9, P > 0.05) and 25 mmHg (control: 155 +/- 9; FR: 150 +/- 10 mmHg, N = 9, P > 0.05). FR also induced eccentric ventricular remodeling, and reduced myocardial elasticity (control: 10.9 +/- 1.6; FR: 9.2 +/- 0.9%, N = 9, P < 0.05) and LV compliance (control: 82.6 +/- 16.5; FR: 68.2 +/- 9.1%, N = 9, P < 0.05). We conclude that FR causes systolic ventricular dysfunction without in vitro change in myocardial contractility and diastolic dysfunction probably due to a reduction in myocardial elasticity.

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Cardiac structures, function, and myocardial contractility are affected by food restriction (FR). There are few experiments associating undernutrition with hypertension. The aim of the present study was to analyze the effects of FR on the cardiac response to hypertension in a genetic model of hypertension, the spontaneously hypertensive rat (SHR). Five-month-old SHR were fed a control or a calorie-restricted diet for 90 days. Global left ventricle (LV) systolic function was evaluated in vivo by transthoracic echocardiogram and myocardial contractility and diastolic function were assessed in vitro in an isovolumetrically beating isolated heart (Langendorff preparation). FR reduced LV systolic function (control (mean ± SD): 58.9 ± 8.2; FR: 50.8 ± 4.8 percent, N = 14, P < 0.05). Myocardial contractility was preserved when assessed by the +dP/dt (control: 3493 ± 379; FR: 3555 ± 211 mmHg/s, P > 0.05), and developed pressure (in vitro) at diastolic pressure of zero (control: 152 ± 16; FR: 149 ± 15 mmHg, N = 9, P > 0.05) and 25 mmHg (control: 155 ± 9; FR: 150 ± 10 mmHg, N = 9, P > 0.05). FR also induced eccentric ventricular remodeling, and reduced myocardial elasticity (control: 10.9 ± 1.6; FR: 9.2 ± 0.9 percent, N = 9, P < 0.05) and LV compliance (control: 82.6 ± 16.5; FR: 68.2 ± 9.1 percent, N = 9, P < 0.05). We conclude that FR causes systolic ventricular dysfunction without in vitro change in myocardial contractility and diastolic dysfunction probably due to a reduction in myocardial elasticity.

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RESUMEN

Food restriction (FR) has been shown to induce important morphological changes in rat myocardium. However, its influence on myocardial performance is not completely defined. We examined the effects of chronic FR on cardiac muscle function and morphology. Sixty-day-old Wistar-Kyoto rats were fed a control (C) or a restricted diet (daily intake reduced to 50% of the amount of food consumed by the control group) for 90 days. Myocardial performance was studied in isolated left ventricular (LV) papillary muscle. Fragments of the LV free wall were analysed by light microscopy, and the ultrastructure of the myocardium was examined in the LV papillary muscle. The myocardial collagen concentration was also evaluated. FR decreased body weight (BW) and LV weight (LVW); the LVW/BW ratio was higher in the restricted group (C, 1.86+/-0.17 mg/g; FR, 2.19+/-0.31 mg/g; p < 0.01). In the FR animals, the cardiac fibers were polymorphic, some of them were of small diameter and others presented lateral infoldings; the ultrastructural alterations were focal and included reduction of sarcoplasmic content, absence and (or) disorganization of myofilaments and Z line, numerous electron dense and polymorphic mitochondria, and deep infoldings of the plasma membrane. The hydroxyproline concentration was higher in the FR animals (p < 0.01). FR prolonged the contraction and relaxation time of the papillary muscle and did not change its ability to contract and shorten. In conclusion, although a 90-day period of FR caused striking myocardial ultrastructural alterations and increased the collagen concentration, it only minimally affected the mechanical function.

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