RESUMEN

Exposure to stress induces a cluster of physiological and behavioral changes in an effort to maintain the homeostasis of the organism. Long-term exposure to stress, however, has detrimental effects on several cell functions such as the impairment of antioxidant defenses leading to oxidative damage. Oxidative stress is a central feature of many diseases. The lungs are particularly susceptible to lesions by free radicals and pulmonary antioxidant defenses are extensively distributed and include both enzymatic and non-enzymatic systems. The aim of the present study was to determine lipid peroxidation and total radical-trapping potential (TRAP) changes in lungs of rats submitted to different models of chronic stress. Adult male Wistar rats weighing 180-230 g were submitted to different stressors (variable stress, N = 7) or repeated restraint stress for 15 (N = 10) or 40 days (N = 6) and compared to control groups (N = 10 each). Lipid peroxidation levels were assessed by thiobarbituric acid reactive substances (TBARS), and TRAP was measured by the decrease in luminescence using the 2-2'-azo-bis(2-amidinopropane)-luminol system. Chronic variable stress induced a 51% increase in oxidative stress in lungs (control group: 0.037 +/- 0.002; variable stress: 0.056 +/- 0.007, P < 0.01). No difference in TBARS was observed after chronic restraint stress, but a significant 57% increase in TRAP was presented by the group repeatedly restrained for 15 days (control group: 2.48 +/- 0.42; stressed: 3.65 +/- 0.16, P < 0.05). We conclude that different stressors induce different effects on the oxidative status of the organism.

Asunto(s)

Peroxidación de Lípido , Pulmón/metabolismo , Estrés Oxidativo , Estrés Fisiológico/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo , Animales , Modelos Animales de Enfermedad , Radicales Libres/metabolismo , Masculino , Ratas , Ratas Wistar , Restricción Física

RESUMEN

Exposure to stress induces a cluster of physiological and behavioral changes in an effort to maintain the homeostasis of the organism. Long-term exposure to stress, however, has detrimental effects on several cell functions such as the impairment of antioxidant defenses leading to oxidative damage. Oxidative stress is a central feature of many diseases. The lungs are particularly susceptible to lesions by free radicals and pulmonary antioxidant defenses are extensively distributed and include both enzymatic and non-enzymatic systems. The aim of the present study was to determine lipid peroxidation and total radical-trapping potential (TRAP) changes in lungs of rats submitted to different models of chronic stress. Adult male Wistar rats weighing 180-230 g were submitted to different stressors (variable stress, N = 7) or repeated restraint stress for 15 (N = 10) or 40 days (N = 6) and compared to control groups (N = 10 each). Lipid peroxidation levels were assessed by thiobarbituric acid reactive substances (TBARS), and TRAP was measured by the decrease in luminescence using the 2-2'-azo-bis(2-amidinopropane)-luminol system. Chronic variable stress induced a 51 percent increase in oxidative stress in lungs (control group: 0.037 ± 0.002; variable stress: 0.056 ± 0.007, P < 0.01). No difference in TBARS was observed after chronic restraint stress, but a significant 57 percent increase in TRAP was presented by the group repeatedly restrained for 15 days (control group: 2.48 ± 0.42; stressed: 3.65 ± 0.16, P < 0.05). We conclude that different stressors induce different effects on the oxidative status of the organism.

Asunto(s)

Animales , Masculino , Ratas , Peroxidación de Lípido , Pulmón , Estrés Oxidativo , Estrés Fisiológico , Sustancias Reactivas al Ácido Tiobarbitúrico , Modelos Animales de Enfermedad , Radicales Libres , Ratas Wistar , Restricción Física

RESUMEN

Rats were made hypertensive by the administration of the nitric oxide synthase inhibitor nitro-L-arginine (LNA, 2.74 mmol/L) in drinking water for 7 d. Hearts from hemodynamically assessed animals were analyzed for lipid peroxidation (LPO), gamma-glutamylcysteine-synthetase (gamma-GCS), glutathione disulfide reductase (GR), glutathione peroxidase (GSHPx), catalase (CAT), superoxide dismutase (SOD), and total radical trapping potential (TRAP) activities. LNA treatment increased the mean arterial blood pressure by 46% and the heart rate by 22% without changing plasma renin activity. LNA treatment resulted in a 30% increase in LPO. gamma-GCS was reduced by 48% and GR by 36% in the cardiac tissue of hypertensive rats as compared to controls. The activity of nonselenium GSHPx was reduced by 27%, and selenium-dependent GSHPx activity in the heart was not affected by LNA treatment. In hypertensive rats, SOD activity was increased by 16%, and CAT was decreased by 46%. TRAP was lower (27%) in the myocardium of hypertensive rats than in that of controls. These data suggest that LNA-induced hypertension is associated with increased myocardial oxidative stress.

Asunto(s)

Antioxidantes/metabolismo , Inhibidores Enzimáticos/farmacología , Hipertensión/inducido químicamente , Hipertensión/metabolismo , Miocardio/metabolismo , Óxido Nítrico Sintasa/antagonistas & inhibidores , Nitroarginina/farmacología , Estrés Oxidativo/fisiología , Animales , Catalasa/metabolismo , Glutamato-Cisteína Ligasa/metabolismo , Glutatión/metabolismo , Glutatión Peroxidasa/metabolismo , Glutatión Reductasa/metabolismo , Corazón/efectos de los fármacos , Hipertensión/enzimología , Masculino , Miocardio/enzimología , Ratas , Ratas Wistar , Renina/sangre , Superóxido Dismutasa/metabolismo

RESUMEN

The effect of Clinostomum detruncatum metacercaria infection on the activities of the antioxidant enzymes superoxide dismutase and catalase in muscle of the freshwater fish Rhamdia quelen was analyzed. Tert-butyl hydroperoxide-initiated chemiluminescence, a measure of lipid peroxidation, was also investigated. Enzyme activities were similar in infected and uninfected fishes. However, the chemiluminescence was almost 2-fold higher in muscle of infected fishes than in muscle of uninfected ones. These results indicate that parasite infection induces oxidative stress and a higher level of membrane damage in the fish muscle due to an imbalance between pro-oxidants and non-enzymatic antioxidants. Our results suggest that fish response to parasite infection could involve, as in other vertebrates, reactive oxygen intermediates.

Asunto(s)

Bagres , Enfermedades de los Peces/parasitología , Peroxidación de Lípido , Músculo Esquelético/parasitología , Trematodos/patogenicidad , Infecciones por Trematodos/veterinaria , Animales , Brasil , Catalasa/análisis , Enfermedades de los Peces/patología , Mediciones Luminiscentes , Músculo Esquelético/enzimología , Músculo Esquelético/patología , Estrés Oxidativo , Conteo por Cintilación/veterinaria , Superóxido Dismutasa/análisis , Infecciones por Trematodos/parasitología , Infecciones por Trematodos/patología , terc-Butilhidroperóxido/química

RESUMEN

The purpose of the present study was to investigate the effects of experimental diabetes on the oxidant and antioxidant status of latissimus dorsi (LD) muscles of male Wistar rats (220 +/- 5 g, N = 11). Short-term (5 days) diabetes was induced by a single injection of streptozotocin (STZ, 50 mg/kg, iv; glycemia >300 mg/dl). LD muscle of STZ-diabetic rats presented higher levels of thiobarbituric acid reactive substances (TBARS) and chemiluminescence (0.36 +/- 0.02 nmol/mg protein and 14706 +/- 1581 cps/mg protein) than LD muscle of normal rats (0.23 +/- 0.04 nmol/mg protein and 7389 +/- 1355 cps/mg protein). Diabetes induced a 92 percent increase in catalase and a 27 percent increase in glutathione S-transferase activities in LD muscle. Glutathione peroxidase activity was reduced (58 percent) in STZ-diabetic rats and superoxide dismutase activity was similar in LD muscle of both groups. A positive correlation was obtained between catalase activity and the oxidative stress of LD, as evaluated in terms of TBARS (r = 0.78) and by chemiluminescence (r = 0.89). Catalase activity also correlated inversely with glutathione peroxidase activity (r = 0.79). These data suggest that an increased oxidative stress in LD muscle of diabetic rats may be related to skeletal muscle myopathy

Asunto(s)

Diabetes Mellitus Experimental , Músculo Esquelético/fisiología , Estrés Oxidativo/fisiología , Estudios de Casos y Controles , Modelos Lineales , Mediciones Luminiscentes , Ratas Wistar , Sustancias Reactivas al Ácido Tiobarbitúrico

RESUMEN

The purpose of the present study was to investigate the effects of experimental diabetes on the oxidant and antioxidant status of latissimus dorsi (LD) muscles of male Wistar rats (220 +/- 5 g, N = 11). Short-term (5 days) diabetes was induced by a single injection of streptozotocin (STZ, 50 mg/kg, iv; glycemia >300 mg/dl). LD muscle of STZ-diabetic rats presented higher levels of thiobarbituric acid reactive substances (TBARS) and chemiluminescence (0.36 +/- 0.02 nmol/mg protein and 14706 +/- 1581 cps/mg protein) than LD muscle of normal rats (0.23 +/- 0.04 nmol/mg protein and 7389 +/- 1355 cps/mg protein). Diabetes induced a 92% increase in catalase and a 27% increase in glutathione S-transferase activities in LD muscle. Glutathione peroxidase activity was reduced (58%) in STZ-diabetic rats and superoxide dismutase activity was similar in LD muscle of both groups. A positive correlation was obtained between catalase activity and the oxidative stress of LD, as evaluated in terms of TBARS (r = 0.78) and by chemiluminescence (r = 0.89). Catalase activity also correlated inversely with glutathione peroxidase activity (r = 0.79). These data suggest that an increased oxidative stress in LD muscle of diabetic rats may be related to skeletal muscle myopathy.

Asunto(s)

Diabetes Mellitus Experimental/metabolismo , Músculo Esquelético/metabolismo , Estrés Oxidativo/fisiología , Animales , Modelos Lineales , Mediciones Luminiscentes , Masculino , Ratas , Ratas Wistar , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo

RESUMEN

Reactive oxygen species are formed in physiological and pathological conditions in mammalian tissues. Because of their high reactivity, they may interact with biomolecules, inducing oxidative injury. Increases in lipid peroxidation can result in oxidative damage to cellular membranes. Protection against oxidative damage is provided by enzymatic and non-enzymatic antioxidant defenses. Antioxidant enzyme activities and lipid peroxidation, as an index of oxidative stress injury, were evaluated in different seasons over one year in the heart and liver of rats, maintained on a 12 h light and dark cycle. Glutathione peroxidase and catalase activities, in both tissues, were maximal in the summer season. Lipid peroxidation in the heart was maximal in the spring as compared to the other seasons and it did not vary in the liver during the year. These findings suggest that any study of antioxidants or oxidative stress must take into account such seasonal variations for a more precise analysis of changes due to any pathological condition.

Asunto(s)

Catalasa/metabolismo , Glutatión Peroxidasa/metabolismo , Hígado/metabolismo , Miocardio/metabolismo , Estrés Oxidativo , Estaciones del Año , Animales , Peroxidación de Lípido , Masculino , Ratas , Ratas Wistar

RESUMEN

Macrophages/foam cells have a pivotal role in atherogenesis although little is known about the way lipid imbalance, a hallmark of atherosclerosis, leads to lipid accumulation in these cells. Modified low-density lipoproteins are associated with macrophage lipid dysfunction in atherosclerosis, but a possible role for altered lipogenesis leading to lipid accumulation remains to be elucidated. Since endothelium-derived nitric oxide (NO) and prostaglandins (PGs) are physiological autacoids whose production may be impaired in atherosclerosis, the effects of these mediators on de novo lipid synthesis in 24-h cultured rat peritoneal macrophages is investigated. In resident (unstimulated) cells, 1 microM PGE2 and the stable analog of PGI2 carbaprostacyclin (cPGI2, 1 microM) deviated the overall [1-14C]acetate from incorporation into cholesterol, free fatty acids and triacylglycerols favoring the formation of phospholipids. In inflammatory (thioglycollate-elicited) macrophages, these eicosanoids likewise reduced 14C-incorporations into all the lipid fractions tested. Also, cPGI2 and PGE2 reduced [4-14C]cholesterol uptake from inflammatory cells but did not interfere in 14C-cholesterol export. The PGE2-derivative PGA2 (10-20 microM) reduced 14C-incorporations into all the lipids in resident cells while it enhanced phospholipid synthesis by up to 129% at the expense of reduced incorporations into the other test lipids. The NO donor S-nitroso-N-acetylpenicillamine (SNAP, 1-10 microM), when added to macrophages in the presence of superoxide dismutase (SOD, to avoid the reaction of superoxide with NO), significantly reduced lipogenesis especially in inflammatory cells. These findings suggest that endothelium-derived NO and PGs may be associated with macrophage lipid accumulation by modulating lipogenesis and cholesterol uptake within these cells.

Asunto(s)

Arteriosclerosis/fisiopatología , Endotelio Vascular/fisiopatología , Metabolismo de los Lípidos , Macrófagos/efectos de los fármacos , Óxido Nítrico/farmacología , Prostaglandinas/farmacología , Acetatos/metabolismo , Animales , Arterias/citología , Células Cultivadas , Colesterol/metabolismo , Ácidos Grasos/metabolismo , Lípidos/biosíntesis , Macrófagos/metabolismo , Macrófagos Peritoneales/efectos de los fármacos , Macrófagos Peritoneales/metabolismo , Penicilamina/análogos & derivados , Penicilamina/farmacología , Fosfolípidos/biosíntesis , Ratas , Superóxido Dismutasa/farmacología , Acetato de Tetradecanoilforbol/farmacología , Factores de Tiempo , Triglicéridos/metabolismo

RESUMEN

Hydrogen peroxide (H2O2) perfused into the aorta of the isolated rat heart induces a positive inotropic effect, with cardiac arrhythmia such as extrasystolic potentiation or cardiac contractures, depending on the dose. The last effect is similar to the "stone heart" observed in reperfusion injury and may be ascribed to lipoperoxidation (LPO) of the membrane lipids, to protein damage, to reduction of the ATP level, to enzymatic alterations and to cardioactive compounds liberated by LPO. These effects may result in calcium overload of the cardiac fibers and contracture ("stone heart"). Hearts from male Wistar rats (300-350g) were perfused at 31°C with Tyrode, 0.2 mM trolox C, 256 mM H2O2 or trolox C + H2O2. Cardiac contractures (baseline elevation of the myograms obtained) were observed when hearts were perfused with H2O2 (Tyrode: 5.9 + 3.2; H2O2: 60.5 + 13.9 percent of the initial value); perfusion with H2O2 increased the LPO of rat heart homogenates measured by chemiluminescence (Tyrode: 3,199 + 259; H2O2: 5,304 + 133 cps mg protein(-1) 60 min(-1), oxygen uptake (Tyrode: 0.44 + 0.1; H2O2: 3.2 + 0.8 nmol min(-1) mg protein(-1) and malonaldehyde (TBARS) foramtion (Tyrode: 0.12 + 0; H2O2: 0.37 + 0.1 nmol/ml). Previous perfusion with 0.2 mM trolox C reduced the LPO (Chemiluminescence: 4,098 + 531), oxygen uptake (0.51 + 0) and TBARS (0.13 + 0) bud did not prevent the H2O2-induced contractures (33.3 + 16 percent). ATP (Tyrode: 2.84 + 0; H2O2: 0.57 + 0) and glycogen levels (Tyrode: 0.46 + 0; H2O22: 0.26 + 0) were reduced by H2O2. Trolox did not prevent these effects (ATP: 0.84 + 0 and glycogen: 0.27 + 0). Trolox C is known to be more effective than alpha-tocopherol or gamma-tocopherol in reducing LPO though it lacks the phytol portion of vitamin E to be fixed to the cell membranes. Trolox C, unlike vitamin A, did not prevent the glycogen reduction induced by H2O2. Trolox C induced a positive chronotropic effect that resulted in higher energy consumption. The reduction of energy level seemed to be more important than LPO in the mechanism of H2O2-induced contracture.

Asunto(s)

Ratas , Animales , Masculino , Antioxidantes/farmacología , Peróxido de Hidrógeno/farmacología , Contracción Miocárdica/efectos de los fármacos , Vitamina E/farmacología , Ratas Wistar

RESUMEN

The effects of exercise training on hemodynamic and metabolic parameters as well as on responses to oxidative stress in aged individuals are controversial. The aim of the present study was to investigate changes in heart hate, mean arterial pressure, vasoreactivity, and plasma levels of insulin and glucose in male aged Wistar rats submitted to exercise training for 11 weeks (1 h/d; 5 d/wk) in a treadmill. The isolated heart was perfused by H2O2, and oxidative stress was evaluated using thiobarbituric acid reactive substances. Cardiovascular functions were recorded with a data acquisition system (CODAS, 1 kHz). Trained aged rats were bradycardic as compared with sedentary aged rats (298+/-7 versus 336+/-16 bpm) but presented similar mean arterial pressure and vasoreactivity and plasma levels of insulin and of glucose, which were quantified by radioimmunoassay and colorimetric enzymatic test. Plasma levels of insulin and of glucose ratio were increased in trained aged rats (6.9+/-0.7 versus 3.5+/-0.4 in sedentary aged rats), and the response to oxidative stress was decreased (0.4+/-0.1 versus 0.7+/-0.1 nmol/mg protein in sedentary aged rats). These results showed that exercise training produced a lower resting heart rate as well as changes in metabolic and oxidative responses. This suggests a higher myocardium protection of trained than sedentary aged rats.

Asunto(s)

Envejecimiento/fisiología , Estrés Oxidativo , Condicionamiento Físico Animal , Animales , Glucemia/análisis , Hemodinámica , Peróxido de Hidrógeno/farmacología , Insulina/sangre , Masculino , Ratas , Ratas Wistar

RESUMEN

Several investigators have demonstrated that streptozotocin (STZ) diabetes induces changes in the autonomic control of the cardiovascular system. Changes in cardiovascular function may be related to peripheral neuropathy. The aim of the present study was to analyze changes in heart rate (HR) and arterial pressure (AP) as well as baroreflex and chemoreflex sensitivity in STZ-induced diabetic male Wistar rats (STZ, 50 mg/kg, i.v., 15 days). Intra-arterial blood pressure signals were obtained for control and diabetic rats (N = 9, each group). Data were processed in a data acquisition system (CODAS, 1 kHz). Baroreflex sensitivity was evaluated by measuring heart rate changes induced by arterial pressure variation produced by phenylephrine and sodium nitroprusside injection. Increasing doses of potassium cyanide (KCN) were used to evaluate bradycardic and pressor responses evoked by chemoreflex activation. STZ induced hyperglycemia (447 +/- 49 vs 126 +/- 3 mg/dl), and a reduction in AP (99 +/- 3 vs 118 +/- 2 mmHg), resting HR (296 +/- 11 vs 355 +/- 16 bpm) and plasma insulin levels (16 +/- 1 vs 57 +/- 11 microU/ml). We also observed that the reflex bradycardia (-16.8 +/- 0.1 vs -12.5 +/- 0.1 bpm/mmHg, in the diabetic group) and tachycardia (-3.68 +/- 0.5 vs -1.75 +/- 0.3 bpm/mmHg, in the diabetic group) produced by vasopressor and depressor agents were impaired in the diabetic group. Bradycardia evoked by chemoreflex activation was attenuated in diabetic rats (control: -17 +/- 1, -86 +/- 19, -185 +/- 18, -208 +/- 17 vs diabetic: -7 +/- 1, -23 +/- 5, -95 +/- 13, -140 +/- 13 bpm), as also was the pressor response (control: 6 +/- 1, 30 +/- 7, 54 +/- 4, 59 +/- 5 vs diabetic: 6 +/- 1, 8 +/- 2, 33 +/- 4, 42 +/- 5 mmHg). In conclusion, the cardiovascular response evoked by baroreflex and chemoreflex activation are impaired in diabetic rats. The alterations of cardiovascular responses may be secondary to the autonomic dysfunction of cardiovascular control.

Asunto(s)

Barorreflejo/efectos de los fármacos , Células Quimiorreceptoras/efectos de los fármacos , Diabetes Mellitus Experimental/fisiopatología , Animales , Presión Sanguínea/efectos de los fármacos , Bradicardia/fisiopatología , Masculino , Ratas , Ratas Wistar , Estreptozocina , Taquicardia/fisiopatología

RESUMEN

Several investigators have demonstrated that streptozotocin (STZ) diabetes induces changes in the autonomic control of the cardiovascular system. Changes in cardiovascular function may be related to peripheral neuropathy. The aim of the present study was to a changes in heart rate (HR) and arterial pressure (AP) as well as baroreflex and chemoreflex sensitivity in STZ-induced diabetic male Wistar rats (STZ, 50 mg/kg, iv, 15 days). Intra-arterial blood pressure signals were obtained for control and diabetic rats (N = 9, each group). Data were processed in a data acquisition system (CODAS, 1 kHz). Baroreflex sensitivity was evaluated by measuring heart rate changes induced by arterial pressure varíation produced by phenyiephrine and sodium nitroprusside injection. Increasing doses of potassium cyanide (KCN) were used to evaluate bradycardic and pressor responses evoked by chemoreflex activation. STZ induced hyperglycemia (447 ñ 49 vs 126 ñ 3 mg/dl), and a reduction in AP (99 + 3 vs 118 + 2mmHg), resting HR (296 ñ 11 vs 355 ñ 16 bpm) and plasma insulin levels (16 ñ 1 vs 57 + 11 muU/ml). We also observed that the reflex bradycardia (-1.68 ñ 0.1 vs -1.25 ñ 0.1 bpm/mmHg, in the diabetic group) and tachycardia (-3.68 ñ 0.5 vs -1.75 ñ 0.3 bpm/mmHg, in the diabetic group) produced by vasopressor and depressor agents were impaired in the diabetic group. Bradycardia evoked by chemoreflex activation was attenuated in diabetic rats (control: -l7 + 1,-86 + 19,-l85 ñ 18, -208 + 17 vs diabetic: -7 + 1,-23 ñ 5,-95 ñ 13, - 140 + 13 bpm), as also was the pressor response (control: 6 ñ 1,30 ñ 7,54 + 59 ñ 5 vs diabetic: 6 ñ 1,8 ñ 2,33 ñ 4,42 ñ 5 mmhg). In conclusion the cardiovascular responses evoked by baroreflex and chemoreflex activation are impaired in diabetic rats. The alterations of caradiovascular responses may be secondary to the autonomic dysfunction of cardiovascular control.

Asunto(s)

Ratas , Animales , Masculino , Barorreflejo/efectos de los fármacos , Células Quimiorreceptoras/efectos de los fármacos , Diabetes Mellitus Experimental/fisiopatología , Estreptozocina/farmacología , Presión Sanguínea/efectos de los fármacos , Bradicardia , Ratas Wistar , Taquicardia

RESUMEN

Hydrogen peroxide (H2O2) perfused into the aorta of the isolated rat heart induces a positive inotropic effect, with cardiac arrhythmia such as extrasystolic potentiation or cardiac contractures, depending on the dose. The last effect is similar to the "stone heart" observed in reperfusion injury and may be ascribed to lipoperoxidation (LPO) of the membrane lipids, to protein damage, to reduction of the ATP level, to enzymatic alterations and to cardioactive compounds liberated by LPO. These effects may result in calcium overload of the cardiac fibers and contracture ("stone heart"). Hearts from male Wistar rats (300-350 g) were perfused at 31 degrees C with Tyrode, 0.2 mM trolox C, 256 mM H2O2 or trolox C + H2O2. Cardiac contractures (baseline elevation of the myograms obtained) were observed when hearts were perfused with H2O2 (Tyrode: 5.9 +/- 3.2; H2O2: 60.5 +/- 13.9% of the initial value); perfusion with H2O2 increased the LPO of rat heart homogenates measured by chemiluminescence (Tyrode: 3,199 +/- 259; H2O2: 5,304 +/- 133 cps mg protein-1 60 min-1), oxygen uptake (Tyrode: 0.44 +/- 0.1; H2O2: 3.2 +/- 0.8 nmol min-1 mg protein-1) and malonaldehyde (TBARS) formation (Tyrode: 0.12 +/- 0; H2O2: 0.37 +/- 0.1 nmol/ml). Previous perfusion with 0.2 mM trolox C reduced the LPO (chemiluminescence: 4,098 +/- 531), oxygen uptake (0.51 +/- 0) and TBARS (0.13 +/- 0) but did not prevent the H2O2-induced contractures (33.3 +/- 16%). ATP (Tyrode: 2.84 +/- 0; H2O2: 0.57 +/- 0) and glycogen levels (Tyrode: 0.46 +/- 0; H2O2: 0.26 +/- 0) were reduced by H2O2. Trolox did not prevent these effects (ATP: 0.84 +/- 0 and glycogen: 0.27 +/- 0). Trolox C is known to be more effective than alpha-tocopherol or gamma-tocopherol in reducing LPO though it lacks the phytol portion of vitamin E to be fixed to the cell membranes. Trolox C, unlike vitamin A, did not prevent the glycogen reduction induced by H2O2. Trolox C induced a positive chronotropic effect that resulted in higher energy consumption. The reduction of energy level seemed to be more important than LPO in the mechanism of H2O2-induced contracture.

Asunto(s)

Antioxidantes/farmacología , Cromanos/farmacología , Peróxido de Hidrógeno/farmacología , Contracción Miocárdica/efectos de los fármacos , Animales , Masculino , Ratas , Ratas Wistar

RESUMEN

A very sensitive method for estimating the concentration of crotamine in a solution was developed. This method was based on the based on the time required for the appearance of permanent hyperextension of the rear legs of mice as a function of the dose administered. This method can be used to determine toxin doses as low as 0.32 mg/kg(-1). Its high specificity for crotamine means that it can be used to measure toxin concentrations in the presence of other proteins and polypeptides.

Asunto(s)

Animales , Ratas , Crotalus , Venenos de Crotálidos/química , Fenómenos Químicos , Reproducibilidad de los Resultados , Venenos de Crotálidos/farmacología

RESUMEN

The aging process is related to several changes in cardiovascular, metabolic and autonomic functions. However, descriptions of changes in arterial pressure (AP), baroreflex sensitivity and associated variations of serum glucose and insulin are controversial. The aim of this paper was to study AP, baroreflex sensitivity and changes in plasma levels of glucose and insulin of young (10 weeks, 239 +/- 4.3 g) and aged (18-24 months, 412 +/- 8.5 g) male Wistar rats. AP pulses were videotaped and processed on a microcomputer, using an analog-to-digital converter (beat-to-beat analysis). Baroreflex sensitivity was evaluated measuring heart rate changes induced by mean arterial pressure (MAP) variations produced by phenylephrine and sodium nitroprusside injections (N = 10 in each group). Plasma glucose (N = 10 in each group) and plasma insulin (N = 6 in each group) were quantified by a colorimetric enzymatic test and radioimmunoassay, respectively. There were no differences in systolic, diastolic or mean AP (110 +/- 5 vs 107 +/- 3 mmHg) between aged and young rats. The tachycardic response to the reduction of AP was impaired in aged compared to young rats (-1.95 +/- 0.29 vs -3.26 +/- 0.49 bpm/mmHg), while the bradycardic response to increases in AP was similar (-1.02 +/- 0.22 vs -1.5 +/- 0.26 bpm/mmHg). Basal levels of glucose (83 +/- 6 vs 62 +/- 4 mg/dl) and insulin (8.3 +/- 2 vs 4 +/- 0.5 microU/ml) were different. Thus, the reflex tachycardia evoked by a fall in AP is depressed in old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Asunto(s)

Envejecimiento/fisiología , Barorreflejo/fisiología , Presión Sanguínea/fisiología , Factores de Edad , Animales , Glucemia/análisis , Insulina/sangre , Masculino , Ratas , Ratas Wistar

RESUMEN

The aging process is related to several changes in cardiovascular, metabolic and autonomic functions. However, descriptions of changes in arterial pressure (AP), baroreflex sensitivity and associated variations of serum glucose and insulin are controversial. The aim of this paper was to study AP, sensitivity and changes in plasma levels of glucose and insulin of young (10 weeks, 239 ñ 4.3 g) and aged (18-24 months, 412 ñ 8.5 g) male Wistar rats AP pulses were videotaped and processed on a microcomputer, using an analog-to-digital converter (beat-to-beat analysis). Baroreflex sensitivity was evaluated measuring heart rate changes induced by mean arterial pressure (MAP) variations produced by phenylephrine and socium nitroprosside injection (N = 10 in each group). Plasma glucose (N = 10 in each group) and plasma insulin (N = 6 in each group) were quantified by a colorimetric enzymatic test and radioimmunoassay,respectively. Ther were no differences in systolic, diastolic or mean AP (110 ñ 5 vs 107 ñ 3 mmHg) between aged and young rats. The tachycardic reponse to the reduction of AP was impaired in aged compared to young rats (-1.95 ñ 0.29 vs -3.26 ñ 0.49 bpm/mmHg), while the bradycardic response to increases in AP was similar (-1.02 ñ 0.22 vs -1.5 ñ 0.26 bpm/mmHg). Basal levels of glucose (83 ñ 6 vs 62 ñ 4mg/dl) and insulin (8.3 ñ 2 vs 4 ñ 0.5 µU/ml) were different. Thus, the reflex tachycardia evoked by a fall in AP is depressed in old rats. The observed higher basal insulin and glucose levels in aged rats may contribute to the imapairment of the baroreflex control

Asunto(s)

Animales , Masculino , Ratas , Envejecimiento/fisiología , Barorreflejo/fisiología , Presión Arterial/fisiología , Factores de Edad , Glucemia/análisis , Insulina/sangre , Ratas Wistar

RESUMEN

The thyroid function was studied by means of a comparison between rats that drank daily less than 2 mEq of a NaCl solution (control) and rats that spontaneously drank daily above 4 mEq of this solution (0.25 M), which is considered aversive to rats. It was found that, in these rats, the protein-bound iodine (PBI-127) and the radioactive iodine uptake (I-131) were less than in the control rats, in spite of similar thyroid weight. It seems, therefore, that the rats that drank high levels of the aversive salt solution have hypothyroidism. This finding shows another link between the thyroid gland and NaCl intake. These data have implications in the design and interpretation of experiments in which NaCl intake is studied.

Asunto(s)

Ingestión de Líquidos/fisiología , Hipotiroidismo/fisiopatología , Cloruro de Sodio/administración & dosificación , Glándula Tiroides/fisiopatología , Equilibrio Hidroelectrolítico/fisiología , Animales , Femenino , Ratas , Hormonas Tiroideas/fisiología

RESUMEN

A technique to anesthetize turtles with ether is presented, in which a plastic cannula is passed through the glottis into the trachea. This procedure avoids apnea and allows ether vapours obtained from a chamber to be introduced, by the animal respiratory movements or by means of a pump, into the animal lungs. The anesthesia is rapidly obtained and lasts from 45-90 minutes. The time of recovery from anesthesia ranged from 60-90 minutes. With this technique no deaths were observed and the same animal could be anesthetized repeatedly.

Asunto(s)

Anestesia Endotraqueal/veterinaria , Anestesia por Inhalación/veterinaria , Éter , Tortugas , Animales , Conducta Animal/efectos de los fármacos

RESUMEN

By using the two-bottle, self-selection method it was found that an excess of thyroid hormone administration to rats increased water and sodium intake. Thyroidectomy changed the initial preference from water to sodium chloride. Oral treatment of the thyroidectomized rats with thyroid hormones brought salt ingestion back to normal levels and greatly augmented the water intake. Two-week treatment was followed by an increase in salt intake, which was characterized by large oscillations resembling the corresponding effects of adrenalectomy and treatment with deoxycorticosterone.

Asunto(s)

Conducta de Ingestión de Líquido/efectos de los fármacos , Cloruro de Sodio , Glándula Tiroides/fisiología , Tiroxina/farmacología , Triyodotironina/farmacología , Animales , Femenino , Ratas , Valores de Referencia , Tiroidectomía

RESUMEN

Se presenta un reporte preliminar de los primeros 20 pacientes en los cuales se utilizó la contrapulsación aórtica como método de asistencia circulatoria. Se revisan los 10 casos en los cuales se utilizó el balón de contrapulsación intraórtico en enfermos que fueron sometidos a revascularización miocárdica de urgencia. De estos 10, 8 eran portadores de angina inestable refractaria a tratamiento médico y 2 fueron operados luego de complicaciones de angioplastia coronaria transluminal percutánea. Hubo 3 muertes (30%) entre los 10 pacientes: 1 por ruptura del balón con embolismo gaseoso fatal, y por falla de ventrículo izquierdo postoperatoria con evidencia de un IM preoperatorio y 1 por un síndrome de dificultad respiratoria de adulto en el postoperatorio tardío. Se presentan los principios de acción de la contrapulsación aórtica y se revisa la literatura sobre el manejo de la angina inestable

Asunto(s)

Humanos , Masculino , Femenino , Angina Inestable/terapia , Venezuela