Sensibilidade e Especificidade da Albumina Modificada pela Isquemia em Ratos Wistar / Sensitivity and Specificity of Ischemia Modified Albumin in Wistar Rats

O infarto agudo do miocárdio (IAM) é uma situação clínica determinada por processo isquêmicoagudo, que resulta em necrose miocárdica. Os marcadores cardíacos em caso de isquemia reversível, atualmente,apresentam sensibilidade limitada.Objetivo: Verificar a sensibilidade da albumina modificada isquêmica (AMI), como marcador cardíaco. Métodos: Estudo experimental, realizado no Laboratório de Experimentação Animal da Universidade Regional Integrada (URI), Erechim, RS, no período de 2011 a 2013. Após a indução isquêmica do miocárdio em ratos da linhagem Wistar-Tecpar, com idade aproximada entre 60-90 dias, através da administração de isoproterenol hidrocloridrato, o conteúdo da AMI foi avaliado em diferentes tempos. Resultados: Os valores da AMI mantiveram-se diminuídos durante as três horas iniciais, após a indução isquêmica pelo isoproterenol hidrocloridrato. Conclusão: Neste estudo, a albumina modificada pela isquemia foi considerada um marcador sensível,principalmente nas três horas iniciais da isquemia...

Background: Acute myocardial infarction (AMI) is a condition determined by an acute ischemic process resulting in myocardial necrosis. Cardiac markers in reversible ischemia currently have limited sensitivity. Objective: To check the sensitivity of ischemia modified albumin (IMA) as a cardiac marker.Methods: Experimental study held at the Animal Experimentation Laboratory of Universidade Regional Integrada (URI), Erechim, RS, from 2011 to 2013. After myocardial ischemic induction in Wistar-Tecpar rats aged about 60-90 days through administration of isoproterenol hydrochloride, the IMA content was evaluated at different times. Results: The IMA values remained reduced during the three first hours after ischemic induction by isoproterenol hydrochloride.Conclusion: In this study, ischemia modified albumin was considered a sensitive marker, particularly in the first three hours of ischemia...

Características clínicas y electrofisiológicas de pacientes fulgurados con radiofrecuencia por taquicardia por reentrada nodal típica / Clinical and electrophysiological characteristics of patients with atrioventricular nodal reentry tachycardia who underwent slow pathway ablation

AV nodal reentry tachycardia (AVNRT) is the most common cause of paroxysmal supraventricular tachycardia. Radiofrequency ablation is today the treatment of choice. Aim: To report our experience in patients who underwent slow pathway ablation. Patients and methods: Fifty six consecutive patients (68% female, mean age 43 years old) that underwent slow pathway ablation are reported. Results: Sixty four percent of patients had failed drug therapy. During electrophysiological study, AVNRT was induced in 55 patients. Isoproterenol was required for induction in 36%. Programmed atrial stimulation revealed dual AV nodal pathway in only 64% of the patients; 29% had AVNRT with single nodal curve and 7% only prolongation of AH interval. The slow pathway was ablated in 55 patients. One patient refused ablation because of risk of AV block. All patients had immediate success post ablation. Sixty four percent of patients persisted with partial evidence of dual curve manifested by sudden AH prolongation and single echoes. Conclusions: Isoproterenol is essential for ruling out AVNRT, since 29% of the patients had baseline single nodal curve and in only 64% was tachycardia induced without isoproterenol. Persistence of residual dual physiology does not rule out the success of ablation (Rev Méd Chile 2003; 131: 1237-42).

Metabolic markers following beta-adrenoceptor agonist infusion in footshock-stressed rats

Stress hormones can alter metabolic functions in adipose tissue and liver, as well as the sensitivity of rat white adipocytes and rat atrial responses to ß-adrenergic agonists. In this study, we examined the effects of three daily footshock stress sessions on the plasma corticosterone, glucose, glycerol and triacylglycerol levels of fed, conscious male rats, and on the plasma glucose, glycerol and triacylglycerol levels of the same rats following iv infusions of ß-adrenergic agonists (isoproterenol: 0.4 nmol kg-1 min-1, noradrenaline: 5.0 æg kg-1 day-1, and BRL 37344 ([+ or -]-[4-(2-[(2-[3-chlorophenyl]-2-hydroxyethyl)amino]propyl)phenoxy]acetic acid), a selective ß3-adrenoceptor agonist: 0.4 nmol kg-1 min-1). Plasma corticosterone levels increased significantly after each stress session, while triacylglycerol levels increased after the first session and glucose increased after the second and third sessions. Glycerol levels were unaltered after stress. These results suggest that repeated footshock stress may induce a metabolic shift from triacylglycerol biosynthesis to glucose release by hepatic tissue, with glycerol serving as one of the substrates in both pathways. Stressed rats were more sensitive to infusion of noradrenaline plus prazosin and to infusion of isoproterenol, with elevated plasma glucose, glycerol and triacylglycerol levels. The higher sensitivity of stressed rats to isoproterenol and noradrenaline was probably related to the permissive effect of plasma corticosterone. Only BRL 37344 increased plasma glycerol levels in stressed rats, probably because ß3-adrenoceptors are not involved in hepatic triacylglycerol synthesis, thus allowing glycerol to accumulate in plasma

Influence of chronic treatment of rats with isoprenaline and calcium channel blockers on response of isolated right ventricle to noradrenaline.

Influence of chronic treatment of rats with and calcium channel blockers (CCBs) and isoprenaline (ISP) on responses to noradrenaline (NA) was investigated on electrically--driven isolated right ventricle preparations. The ventricles were obtained from animals treated with chronic ISP or CCBs alone and chronic nifedipine, verapamil, diltiazem or nimodipine plus chronic ISP. A decreased response to NA as evidenced by an increase in EC50 for contraction which was observed in chronic ISP- treated preparations may be due to development of desensitisation (down-regulation) of beta-adrenoceptors. In chronic CCB-treated preparations there was a significant decrease in the EC50 of NA and decreased contractile response suggesting an increase in the beta-adrenoceptors and decreased availability of calcium, respectively. In chronic CCBs + ISP treated preparations further decreases in the EC50 values were observed suggesting that the voltage gated L-type Ca2+ channels may be affected directly or indirectly by change in beta-adrenoceptor activity. By the above results a proposed mechanism of interrelationship of beta-adrenoceptors with voltage gated L-type calcium channels in cardiac muscle is supported.

Modulaçäo do estresse oxidativo em glândulas submandibulares de rato / Modulation of oxidative stress in rat submandibular glands

As espécies reativas de oxigênio geradas in vivo têm sido implicadas em vários mecanismos como apoptose, crescimento e diferenciação celular, câncer e inflamação. O estresse oxidativo é o produto do desbalanço entre os agentes pro-oxidantes e antioxidantes celulares, causando danos por meio da peroxidação lipídica, oxidação de proteínas e de DNA. Neste trabalho, avaliou-se o efeito do estresse oxidativo em glândulas submandibulares de rato e em células acinares dispersas tratadas com isoproterenol (ISO), cicloheximida (CHX), carbacol (CA) e propanolol (PROP). Observou-se aumento dos níveis de MDA em homogenados de glândulas de ratos tratados com ISO e CHX e em células acinares dispersas incubadas com ISO e CHX...

Effect of acute administration of isoproterenol on submandibular salivary gland of female rat.

The functions of salivary glands are under the regulation of both sympathetic as well as parasympathetic nerve fibers. Further, it has also been demonstrated that chronic administration of a beta-adrenergic agonist isoproterenol (IPR) results in hypertrophy and hyperplasia of submandibular gland [Schneyer C A, Am J Physiol, 203 (1962) 232]. Specific purpose of the present attempt was to look for metabolic responses of submandibular gland of oestrous female rats at very short intervals after 10 min of administration of 5, 10 and 15 micrograms of IPR to females in oestrous condition; pharmacological action and clearance time being only 8 min. The results indicated significant reduction in case of enzymic activities of phosphorylase, total ATPase and Na(+)-K+ ATPase. Cyclic AMP-specific phosphodiesterase and succinate dehydrogenase activities were suppressed only with 5 micrograms dose, but with rising dose levels the effect was not so apparent. Protein content of the gland was reduced slightly by administration of IPR. Hence, it became clear that submandibular gland responds rapidly to IPR administration. Implications of these observations are discussed.

Involvement of K+ channels in the relaxant responses to various agonists in estrogen primed rat uterus.

The present investigation was undertaken to study the effects of K+ channel openers in the relaxant responses to various agonists in estrogen primed rat uterus. Adrenaline and isoprenaline produced a dose-dependent relaxation in the estrogen primed rat uterus. The relaxant responses were found to be significantly potentiated when the preparations were exposed to PSS devoid of calcium. The responses to isoprenaline were found to be greater in the preparations depolarized with 40 mM KCl instead of 80 mM KCl. KCl failed to produce any contractile effect in the presence of D-600. Further, the addition of D-600 completely relaxed the KCl depolarized rat uterus. Pinacidil and cromakalim failed to relax 80 mM KCl depolarized rat uterus. However, they produced dose-dependent relaxation in the preparations depolarized with 40 mM KCl. The relaxant responses to pinacidil and cromakalim were competitively blocked by procaine. However, they were not altered by either propranolol or cimetidine. The relaxant responses to isoprenaline and histamine were found to be potentiated by pinacidil and cromakalim. These results indicate that in rat uterus in addition to adenylate cyclase c-AMP, potassium channels are also involved in the relaxant responses to isoprenaline and histamine.

Effect of conbined administration of counterregulatory hormones during insulin-induced hypoglycemia in rats: lipolysis mediated by a Beta-adrenergic mechanism contributes to hyperglycemia

The synergistic effect of combined injection of glucagon (G), cortisol (C) and phenylephrine + isoproterenol (E) during hypoglycemia in male adult Wistar rats was investigated. For this purpose we injected insulin (1 mg/kg), individually or combined (G+C, G+E, C+E and C+G+E). All drugs were injected ip and all rats were killed 60 min after insulin injection. The rise in glycemia with C+G+E was greater (delta = 107 mg/dl) than the sum of the responses to injection of C, G and E individually, or in double combination plus any single hormone injection. This synergistic effect was reproduced by G + C + isoproterenol (Iso) but not by G + C + phenylephrine (delta = 0 mg/dl). The results also showed a clear relationship between hyperglycemia and lipolysis. Thus, lipolysis mediated by a ß-adrenergic mechanism played a significant role in promoting hyperglycemia when Iso was combined with G and C

Estudo morfométrico do crescimento de glândulas submandibulares de ratos tratados com isoproterenol. II. Modificaçöes no comportamento dos ductos granulosos / Morphometric study of the rat submandibular glands enlargement induced by isoproterenol. II. Changes in the convoluted granular tubule compartment

Estudou-se através de métodos estereológicos ao microscópio óptico, as modificaçöes que ocorrem no compartimento dos ductos granulosos de glândulas submandibulares de ratos induzidos ao crescimento por injeçöes de cloridrato de isoproterenol por 14 dias. A análise dos resultados obtidos mostrou que as dimensöes morfométricas absolutas do sistema de ductos granulosos, praticamente näo se modificaram durante todo o período de crescimento glandular induzido pelo isoproterenol, assim o seu volume total, o volume celular médio, o número total de células e o comprimento total, mantiveram-se ao redor, respectivamente, de 39mmü, 972µmü, 34x10(6) células e 86m. As únicas dimensöes morfométricas que exibiram modificaçöes estatisticamente significativas foram a sua densidade de volume na glândula e o seu diâmetro externo, ambas no intervalo de 0 a 3 dias de tratamento, quando decresceram, respectivamente, de 48 por cento e 21 por cento. Desse modo, os resultados mostraram que as células serosas dos ductos granulosos, ao contrário das células acinosas, näo exibem o efeito sialadenotrófico quando submetido a tratamento crônico com isoproterenol

Estudos estereológico do crescimento de glândulas submandibulares de ratos induzido pelo isoproterenol. I. Modificaçöes no comportamento acinar / Stereological study of the rat submandibular glands growth induced by isoproterenol. I. Changes in the acinar compartment

O objetivo desta pesquisa foi de verificar, através de quantificaçöes esteriológicas ao microscópio óptico, a participaçäo dos processos hiperplásicos e hipertrófico no crescimento do comportamento dos ácinos de glândulas submandibulares de ratos machos, induzido por injeçöes diárias de cloridrato de isoproterenol por 14 dias. A análise dos resultados obtidos mostrou que: a) a massa glandular aumentou 135,8 por cento entre 0 a 14 dias, sendo que entre 0 a 3 dias foi observada a maior velocidade de crescimento; b) a densidade de volume, ou seja, o percentual de volume glandular ocupada pelos ácinos aumentou nos períodos de 0 a 3 e 5 a 7 dias, respectivamente, de 1,33 e 1,10 vezes; c) o volume absoluto desse comportamento passou de 131,9 milímetros cúbicos aos 0 dias para 522,5 milímetros cúbicos aos 14 dias de tratamento, o que representou um aumento de 296,1 por cento; d) o volume celular médio exibiu um soberbo crescimento de 585,4 por cento após 14 dias de tratamento, sendo que entre 0 a 3 e 5 a 7 dias, os aumentos foram, respectivamente, 286,3 por cento e 45 por cento; e) o número absoluto ora apresentados, mostraram que o crescimento do volume total do comportamento acinar de glândulas submandibulares de ratos induzidos pelo isoproterenol, ocorre essencialmente por um mecanismo hipertrófico

Effects of intrathecal administration of adrenergic agonists on the frequency of copulatory pelvic thrusting of the male rat

The effects of the intrathecal perispinal administration of adregergic agonists on the characteristic of frequency, duration, and vigor of pelvic thrusting displayed by male rats during copulation was assessed by an accelerometric technique. A different dose of one drug (noradrenaline, clonidine or isoproterenol) and saline as control was administered at the lumbosacral level of the spinal cord to sexually active male rats in tests of sexual behavior performed at weekly intervals. The intrathecal administration of noradrenaline (alpha-adrenoceptor agonist) increased the frequency of pelvic thrusting in mount and intromission responses, whereas both the alpha2-adrenoceptor agonist clinidine (25 µg) and the ß-adrenoceptor agonist isoproterenol ( 40 µg) reduced the frequency of pelvic thrusting in these responses as compared to values obtained under the intrathecal administration of saline. On the other hand, the duration of the thrusting trains and the potency or vigor of pelvic thrusting in mounts and intromissions did not differ from values obtained under saline treatment. These findings indicate a possible participation of noradrenaline in the modulation of the spinal mechanisms involved in the generation of rhytmic pelvic thrustint performed by the male rat during copulation

Effect of aspirin on isoproterenol induced changes in lipid metabolism in rats.

The effect of aspirin on isoproterenol induced changes in lipid metabolism in rats was studied. Aspirin (1.2 mg/100 g/day) was administered orally for a period of 60 days along with/without isoproterenol (20 mg/100g sc twice at a time interval of 24 h for 2 days). Isoproterenol treated rats showed an increase in the levels of heart cholesterol, triglycerides and free fatty acids. The activity of cholesterol ester synthetase CES was increased significantly with concomitant increase in heart lipid peroxide levels in isoproterenol treatment. Aspirin treatment could restore the enzyme activity to near normal and also reduce the level of lipid peroxides. The lipid changes were minimum in rats treated with aspirin and isoproterenol.

Brain serotoninergic stimulation mreduces the water intake induced by systemic and central beta-adrenergic administration

This study was undertaken to determine if the stimulation of central serotoninergic receptors affects the thirst-inducing action of systemically or intracerebroventricularly (icv) injected isoproterenol. Male Wistar rats weighing 220-300 g were used in groups of 10-14 animals each. Normally hydrated rats implanted with a delay cannula into the third ventricle were injected icv with the 5HT1C/5HT2 agonist MK212 (50 nmol/2 ul) prior to administration of isoproterenol sc (330 ug/kg body weight) or icv (10 and 25 and 50 ug/2 ul). Icv injections of MK212 reduced the water intake induced by isoproterenol injected systemically (56%) and by the two lowest doses of isoproterenol injected icv (76 and 86%, respectively). The results suggest that the central serotoninergic system modulates the central beta-adrenergic system involved in water intake. Taken together with previous results mshowing that the activation of 5HT1C/5HT2 receptorspromotes a rfeduction of the dipsogenic response avoked by water deprivation or by icv injection of angiotensin II or carbachol, the present data suggest that the central serotoninergic system plays a ubiquitous role in thje modulation of water intake behavior

Diferenciación de los soplos sitólicos expulsivos y regurgitantes con isoproterenol inhalado / The differentiation between ejection and regurgitant murmurs by means of inhalation of isoproterenol

Un problema clínico frecuente es la diferenciación entre los soplos sistólicos expulsivos y regurgitantes. La inhalación de nitrito de amilo para este propósito es útil pues aumenta la intensidad de los primeros y disminuye la de los segundos. Debido a la dificultad de conseguir este farmáco, se ensayó el sioproterenol inhalado en diecisiete pacientes con soplos expulsivos y en dieciocho con soplos regurgitantes. El isoproternol se administró a las dosis de 480 a 640 mcg, según la edad y corpulencia. Las modificaciones de los soplos y de la frecuencia cardiaca se expresaron como porciento del cambio con respecto a las valores basales. La frecuencia cardíaca aumentó en ambos grupos. La amplitud de los soplos expulsivos aumentó de inmediato, llegando a un máximo a los 45", en tanto que la de los regurgitantes disminuyó de inmediato y al máximo a los 15". Se concluye que el isoproterenol inhalado, con efecto parecidos a los del nitrito de amilo, puede substituír a éste en la diferenciación clínica y fonocardiográfica de los soplos expulsivos y regurgitantes