A single resistance exercise session improves myocardial contractility in spontaneously hypertensive rats.

Resistance training evokes myocardial adaptation; however, the effects of a single resistance exercise session on cardiac performance are poorly understood or investigated. This study aimed to investigate the effects of a single resistance exercise session on the myocardial contractility of spontaneously hypertensive rats (SHRs). Male 3-month-old SHRs were divided into two groups: control (Ct) and exercise (Ex). Control animals were submitted to sham exercise. Blood pressure was measured in conscious rats before the exercise session to confirm the presence of arterial hypertension. Ten minutes after the exercise session, the animals were anesthetized and killed, and the hearts were removed. Cardiac contractility was evaluated in the whole heart by the Langendorff technique and by isometric contractions of isolated left ventricular papillary muscles. SERCA2a, phospholamban (PLB), and phosphorylated PLB expression were investigated by Western blot. Exercise increased force development of isolated papillary muscles (Ex=1.0±0.1 g/mg vs Ct=0.63±0.2 g/mg, P<0.05). Post-rest contraction was greater in the exercised animals (Ex=4.1±0.4% vs Ct=1.7±0.2%, P<0.05). Papillary muscles of exercised animals developed greater force under increasing isoproterenol concentrations (P<0.05). In the isolated heart, exercise increased left ventricular isovolumetric systolic pressure (LVISP; Δ +39 mmHg; P<0.05) from baseline conditions. Hearts from the exercised rats presented a greater response to increasing diastolic pressure. Positive inotropic intervention to calcium and isoproterenol resulted in greater LVISP in exercised animals (P<0.05). The results demonstrated that a single resistance exercise session improved myocardial contractility in SHRs.

Acute lead-induced vasoconstriction in the vascular beds of isolated perfused rat tails is endothelium-dependent

Chronic lead exposure induces hypertension in humans and animals, affecting endothelial function. However, studies concerning acute cardiovascular effects are lacking. We investigated the effects of acute administration of a high concentration of lead acetate (100 µÌ) on the pressor response to phenylephrine (PHE) in the tail vascular bed of male Wistar rats. Animals were anesthetized with sodium pentobarbital and heparinized. The tail artery was dissected and cannulated for drug infusion and mean perfusion pressure measurements. Endothelium and vascular smooth muscle relaxation were tested with acetylcholine (5 µg/100 µL) and sodium nitroprusside (0.1 µg/100 µL), respectively, in arteries precontracted with 0.1 µM PHE. Concentration-response curves to PHE (0.001-300 µg/100 µL) were constructed before and after perfusion for 1 h with 100 µÌ lead acetate. In the presence of endothelium (E+), lead acetate increased maximal response (Emax) (control: 364.4 ± 36, Pb2+: 480.0 ± 27 mmHg; P < 0.05) and the sensitivity (pD2; control: 1.98 ± 0.07, 2.38 ± 0.14 log mM) to PHE. In the absence of endothelium (E-) lead had no effect but increased baseline perfusion pressure (E+: 79.5 ± 2.4, E-: 118 ± 2.2 mmHg; P < 0.05). To investigate the underlying mechanisms, this protocol was repeated after treatment with 100 µM L-NAME, 10 µM indomethacin and 1 µM tempol in the presence of lead. Lead actions on Emax and pD2 were abolished in the presence of indomethacin, and partially abolished with L-NAME and tempol. Results suggest that acute lead administration affects the endothelium, releasing cyclooxygenase-derived vasoconstrictors and involving reactive oxygen species.

Acute lead-induced vasoconstriction in the vascular beds of isolated perfused rat tails is endothelium-dependent.

Chronic lead exposure induces hypertension in humans and animals, affecting endothelial function. However, studies concerning acute cardiovascular effects are lacking. We investigated the effects of acute administration of a high concentration of lead acetate (100 microMu) on the pressor response to phenylephrine (PHE) in the tail vascular bed of male Wistar rats. Animals were anesthetized with sodium pentobarbital and heparinized. The tail artery was dissected and cannulated for drug infusion and mean perfusion pressure measurements. Endothelium and vascular smooth muscle relaxation were tested with acetylcholine (5 microg/100 microL) and sodium nitroprusside (0.1 microg/100 microL), respectively, in arteries precontracted with 0.1 microM PHE. Concentration-response curves to PHE (0.001-300 microg/100 microL) were constructed before and after perfusion for 1 h with 100 microMu lead acetate. In the presence of endothelium (E(+)), lead acetate increased maximal response (E(max)) (control: 364.4 +/- 36, Pb2(+): 480.0 +/- 27 mmHg; P < 0.05) and the sensitivity (pD(2); control: 1.98 +/- 0.07, 2.38 +/- 0.14 log mM) to PHE. In the absence of endothelium (E(-)) lead had no effect but increased baseline perfusion pressure (E(+): 79.5 +/- 2.4, E-: 118 +/- 2.2 mmHg; P < 0.05). To investigate the underlying mechanisms, this protocol was repeated after treatment with 100 microM L-NAME, 10 microM indomethacin and 1 microM tempol in the presence of lead. Lead actions on E(max) and pD(2) were abolished in the presence of indomethacin, and partially abolished with L-NAME and tempol. Results suggest that acute lead administration affects the endothelium, releasing cyclooxygenase-derived vasoconstrictors and involving reactive oxygen species.

Efeito clínico do uso do parecoxib em modelo de sinovite induzida em pôneis / Clinical effect of parecoxib in induced synovitis in horses

Um modelo experimental de sinovite em pôneis foi usado para avaliar o efeito do parecoxib, um antiinflamatório não-esteroidal (AINE) seletivo injetável. Cinco dias após indução da sinovite, três pôneis foram tratados com 0,55mg/kg/dia (IV) de parecoxib e três receberam solução salina 0,9 por cento (IV) por cinco dias. A avaliação de parâmetros clínicos dos animais e físico-químicos do líquido sinovial foi realizada antes da indução de sinovite, antes e 12, 24, 48, 72, 96 e 120 horas após o início do tratamento. A injeção intra-articular com adjuvante completo de Freund induziu sinovite de intensidade moderada a grave. Os pôneis tratados com parecoxib apresentaram diminuição do grau de claudicação; manutenção da flexão articular, do comprimento do passo, da temperatura retal e da freqüência cardíaca; e atenuação do grau de efusão articular. Embora o parecoxib, na dose utilizada, não tenha apresentado efeito sobre os parâmetros do líquido sinovial das articulações com sinovite, sua ação antipirética, antiinflamatória e principalmente analgésica foi observada.

An experimental synovitis model was used in ponies to evaluate the effect of parecoxib, a selective non steroidal anti-inflammatory drug (NSAID). Five days after synovitis induction, three ponies received parecoxib (IV) 0.55mg/kg/day and three ponies received sterile 0.9 percent saline solution (IV) for five days. Clinical parameters and synovial fluid were evaluated before synovitis induction, prior treatment and 12, 24, 48, 96, and 120 hours after the first treatment. The intra-articular injection of Freund's complete adjuvant induced a moderate to severe synovitis. The parecoxib treated ponies showed lameness reduction; maintenance of stride length, articular flexion, temperature, and heart rate; and attenuation of articular effusion. Although the used dosage of parecoxib had no effect on evaluated synovial fluid parameters, antipyretic, anti-inflammatory, and especially analgesic effects were observed.

Post-resistance exercise hypotension in spontaneously hypertensive rats is mediated by nitric oxide.

1. Postexercise hypotension (PEH) plays an important role in the non-pharmacological treatment of hypertension. It is characterized by a decrease in blood pressure (BP) after a single bout of exercise in relation to pre-exercise levels. 2. The present study investigated the effect of a single session of resistance exercise, as well as the effect of nitric oxide (NO) and the autonomic nervous system (ANS), in PEH in spontaneously hypertensive rats (SHR). 3. Catheters were inserted into the left carotid artery and left jugular vein of male SHR (n = 37) for the purpose of measuring BP or heart rate (HR) and drug or vehicle administration, respectively. Haemodynamic measurements were made before and after acute resistance exercise. The roles of NO and the ANS were investigated by using N(G)-nitro-L-arginine methyl ester (L-NAME; 15 mg/kg, i.v.) and hexamethonium (20 mg/kg, i.v.) after a session of acute resistance exercise. 4. Acute resistance exercise promoted a pronounced reduction in systolic and diastolic BP (-37 +/- 1 and -8 +/- 1 mmHg, respectively; P < 0.05), which was suppressed after treatment with L-NAME. The reduction in systolic BP caused by exercise (-37 +/- 1 mmHg) was not altered by the administration of hexamethonium (-38 +/- 2 mmHg; P > 0.05). After exercise, the decrease in diastolic BP was greater with hexamethonium (-26 +/- 1 mmHg; P < 0.05) compared with the decrease caused by exercise alone. 5. The results suggest that acute resistance exercise has an important hypotensive effect on SHR and that NO plays a crucial role in this response.

[Street cleaners: occupational accidents in the city of Ribeirão Preto, State of São Paulo, Brazil]. / Varredores de rua: acidentes de trabalho ocorridos na cidade de Ribeirão Preto, estado de São Paulo, Brasil.

The work of street sweepers is to sweep waste materials thrown at public streets. It is considered insalubrious due to the close contact that exposes workers to agents present in the urban waste. As street orderlies perform their duties in an open environment, they are submitted to different types of problems. The purpose of this study is to investigate the registered occupational accidents occurred among street orderlies in the city of Ribeirão Preto, State of São Paulo, during 1993 and 1994. Authors aimed at verifying: the number of works that suffered accidents and the notified occupational accidents; data related to the identification of those accidents at the employer company and specific data regarding the occupational accidents. Therefore, authors analyzed the occupational health reports recorded at the National Institute of Social Security at the Regional Bureau of Health (RBH) and at the employer company. Results were shown to the employers and to the RBH. Authors organized meetings to discuss with them the occupational problems they found.