El diagnóstico electrovectocardiográfico de zona inactivable miocárdica / Electrovectocardiographic diagnosis of myocardial inactivable zone

Se subraya la importancia clínica de la exploración vectocardiográfica (alejada y espacial) del fenómeno eléctrico del miocardio, lo que constituye una integración muy útil de la exploración electrocardiográfica (cercana y analítica). Se discuten los cambios morfológicos y cronológicos más característicos debidos a una zona miocárdica inactivable, en función del proceso de despolarización ventricular. Se ilustran algunas manifestaciones electrovectocardiográficas típicas de dicha entidad patológica, subrayando el valor semiológico de los elementos complementarios que la vectocardiografía es capaz de aportar a la electrocardiografía. Ambas integran una exploración racional de la actividad eléctrica del miocardio, la que representa la base firme de las decisiones pronósticas y de la conducta terapeútica en presencia de un cuadro de infarto.

Concentraçöes catiônicas no miocárdio e músculo esquelético de ratos normo e hipertensos (SHR), jovens e adultos / Cation concentrations in myocardium and skeletal muscle of normotensive rats (SHR), young and adults

Estudou-se em ratos normo (NWR) e hipertensos (SHR) jovens com idade de 14-16 semanas e adultos com 19-21semanas de idade as concentraçöes catiônicas de Mg2+, Ca2+, Zn2+ e tambem Na+ e K+ em miocárdio e músculo esquelético. As análises foram efetuadas em espectrofotômetro de absorçäo atômica. As variaçöes da distribuiçäo eletrolítica encontradas foram semelhantes no miocárdio e no músculo esquelético. As amostras obtidas de animais jovens NWR e SHR continham menor concentraçäo de cálcio, zinco e sódio e maior concentraçäo de magnésio e potássio, em comparaçäo com dados obtidos de animais adultos. A evoluçäo idade-dependente do quociente [K+]/[Na+] (maior em jovens; menor em adultos) é conseqüência de retençäo de Na+ e depleçäo de K+ e indica que possivelmente há um envolvimento (diminuiçäo?) da atividade Na+ - K+ ATPase no miocárdio em adultos (NWR e SHR). O quociente [Na+] x [K+] / [Ca2+] x [Mg2] é aumentado em animais hipertensos (SHR), principalmente no músculo esquelético, em conseqüência do aumento do produto [Na+] x [K+] em animais jovens e da reduçäo do produto [Ca2+] x [Mg2+] em animais adultos. A comparaçäo dos parâmetros entre animais normo (NWR) e hipertensos (SHR) revela que os SHRs adultos contêm mais líquido nos tecidos estudados; também no miocárdio e no músculo esquelético de SHRs foram encontradas maiores concentraçöes de zinco e menores concentraçöes de cálcio; as mesmas tendências foram observadas também em animais jovens, podendo-se, portanto, concluir que estas variaçöes säo geneticamente determinadas. A depleçäo da Na+ e K+ observada somente em miocárdio de SHRs adultos é considerada um sinal de adaptaçäo à hipertensäo, com hipertrofia ventricular, enquanto que a reduçäo de magnésio tecidual parece ser idade-dependente

Avaliaçäo experimental das variaçöes dos níveis de glicogênio, lípides totais, triglicérides e água no miocárdio submetido a parada anóxica hipotérmica / Experimental evaluation of the variations of glycogen, total lipids, triglycerides and water levels in the myocardium subjected to anoxic hypothermic arrest

Analisam-se as variaçöes tissulares miocárdicas de glicogênio, lípides, triglicérides e teores de água que ocorreram em dois grupos de cäes submetidos a parada cardíaca anóxica sob circulaçäo extracorpórea, respectivamente em normotermia e hipotermia sistêmica de 28-C. Houve quedas dos níveis de glicogênio nos dois grupos sem diferenças significativas entre eles. Os níveis miocárdicos de lípideos totais apresentaram-se relativamente estáveis nos cäes a 28-C e apresentaram quedas expressivas no grupo sob normotermia. Os níveis de triglicérides mantiveram-se relativamente estáveis nos primeiros 30 minutos de anóxia, apresentando a partir daí quedas expressivas. Os teores de água decresceram em ambos os grupos, particularmente nos cäes operados sob normotermia

Distribution of 5-hydroxytryptamine and histamine in tissues of WLH chicken.

5-Hydroxytryptamine and histamine were estimated in lungs, liver, spleen and adrenals of chicken. A substantial amount of both the amines was found in all the organs. The highest level of both the amines was found in adrenals followed by spleen, lungs and liver. The level of 5-hydroxytryptamine was, however, higher than histamine in all the tissues except adrenals.

Abnormal cardiovascular and electrocardiographic profiles and cardiac glycogen content in rabbits injected with scorpion venom.

Cardiovascular and ECG abnormalities were studied following injection of venom of Buthus tamulus, a common scorpion found in South India. Venom was administered in doses of 2 and 4 mg/kg body weight. Subsequent estimation of glycogen content of different chambers of the heart, showed a significant reduction in tissue glycogen levels in both atria and ventricles in animals treated with a venom dose of 2 mg/kg. However, a significant reduction occurred only in atria with a higher venom dose of 4 mg/kg.

Studies in tissue glycogen in acute stress.

The glycogen was estimated in liver, cardiac and skeletal muscles during the recovery period after electro-shock. The supercompensation in the level of glycogen was observed in cardiac and skeletal muscles at 1 1/2 and 5 hrs respectively during the recovery period, after electro-shock. The liver glycogen level was lower than the control value after electro-shock at least upto 5 hrs of recovery period. Further, the glycogen level was observed to be minimum when the ventricular glycogen showed its supercompensation at 1 1/2 hr of recovery period. The glycogen level of those three tissues returned to control level after 24 hrs of electro-shock.

Effect of foot-electroshock stress on cholinergic activity, tissue glycogen and blood sugar in albino rats.

The immediate or 24 hr delayed effects of 1-day (1-DS) or (7-DS) foot-electroshock stress in albino rats were studied on cardiac acetylcholine (ACh), blood and cardiac cholinesterase (ChE) activities, cardiac, hepatic and muscle glycogen contents and blood sugar concentrations. The effects of physostigmine (PHY), atropine, 6-hydroxydopamine (6-HD), vagotomy and adrenalectomy on 1-DS induced changes were also studied. 1-DS produced an increase in cardiac ACh content which lasted for 24 hr but repeated stress showed phenomenon of adaptation. There seems to be activation of autonomic cholinergic system in stress. 1-DS and 7-DS produced a short-lived inhibition of blood ChE activity and 7-DS also of cardiac ChE activity. Inhibition of ChE activity was probably related to release of adrenaline from adrenal medulla. 1-DS produced hepatic and muscle glycogenolysis with slight hypoglycaemia but without any effect on cardiac glycogen. Following repeated stress there was a phenomenon of adaptation. The hepatic and muscle glycogenolysis produced by stress is due to the release of adrenaline from adrenal medulla. Normally functioning cardiac cholinergic system seems to have a protective effect on heart against stress, in the absence of which cardiac glycogenolysis is induced by stress.

Effects of seasonal variations, acute hypothermia and physostigmine on cardiac acetylcholine, tissue glycogen and blood sugar concentrations in frogs.

The effects of seasonal variations and the effects of acute hypothermia (8.0 degrees) and/or physostigmine (PHY) in different seasons have been studied on the tissue glycogen, cardiac acetylcholine (ACh) and blood sugar contents in frogs. Seasonal variations had no significant effect on cardiac cholinergic activity. However, cardiac ACh concentration was significantly reduced by hypothermia in all seasons. The extents of increase in cardiac ACh in PHY pretreated hypothermic frogs indicate that hypothermia depresses cardiac cholinergic acitity much more in summers than in rainy and winter seasons. The tissue glycogen contents and blood sugar concentrations were significantly lower in winter season than those in summer and rainy seasons. Hypothermia produced marked tissue glycogenolysis and hyperglycaemia during summer and rainy seasons and not during winters. In general PHY had no effect on tissue glycogen contents in any season, but it produced hyperglycaemia during rainy and winter seasons. PHY pretreatment increased cardiac, hepatic and muscle glycogen contents and produced hyperglycaemia in hypothermic winter frogs, and it increased ventricular and muscle glycogen contents during summer and hepatic glycogen during rainy seasons, there being no significant effects on blood sugar.

Hypothermia and acetylcholine content of dog heart.

The acetylcholine level of dog heart has been determined under hypothermia. It was increased at 28 degrees C, and decrease at 20 degrees C. Further, it was observed that the heart rate and blood pressure decreased with gradual reduction in the body temperature of the dog and ventricular fibrillation occurred in 50% of the animals at 20 degrees C. It is proposed that cholinergic agents may have a role as antifibrillatory agents in hypothermia.