Strain differences in baroceptor reflex in adult Wistar Kyoto rats

OBJECTIVES: A subset of normotensive Sprague-Dawley rats show lower baroreflex sensitivity; however, no previous study investigated whether there are differences in baroreflex sensitivity within this subset. Our study compared baroreflex sensitivity among conscious rats of this specific subtype. METHODS: Male Wistar Kyoto (WKY) rats (16 weeks old) were studied. Cannulas were inserted into the abdominal aortic artery through the right femoral artery to measure mean arterial pressure (MAP) and heart rate (HR). Baroreflex gain was calculated as the ratio between change in HR and MAP variation (ÄHR/ÄMAP) in response to a depressor dose of sodium nitroprusside (SNP, 50 µg/kg, i.v.) and a pressor dose of phenylephrine (PE, 8 µg/kg, i.v.). Rats were divided into four groups: 1) low bradycardic baroreflex (LB), baroreflex gain (BG) between -1 and -2 bpm/mmHg tested with PE; 2) high bradycardic baroreflex (HB), BG < -2 bpm/mmHg tested with PE; 3) low tachycardic baroreflex (LT), BG between -1 and -2 bpm/mmHg tested with SNP and; 4) high tachycardic baroreflex (HT), BG < -2 bpm/mmHg tested with SNP. Significant differences were considered for p < 0.05. RESULTS: Approximately 37 percent of the rats showed a reduced bradycardic peak, bradycardic reflex and decreased bradycardic gain of baroreflex while roughly 23 percent had a decreased basal HR, tachycardic peak, tachycardic reflex and reduced sympathetic baroreflex gain. No significant alterations were noted with regard to basal MAP. CONCLUSION: There is variability regarding baroreflex sensitivity among WKY rats from the same laboratory.

A hipotermia como estratégia protetora de encefalopatia hipóxico-isquêmica em recém-nascidos com asfixia perinatal / Hypothermy as a protective strategy in asphyxiated newborns after hypoxic-ischemic encephalopathy

INTRODUÇÃO: a encefalopatia hipóxico isquêmica neonatal é uma doença devastadora para o cérebro do recém-nascido. Nas últimas duas décadas, as pesquisas experimentais trouxeram grande avanço nos conhecimentos fisiopatológicos. Para a integridade neuronal, é necessária energia suficiente para a célula manter o equilíbrio iônico. A hipotermia tem sido estudada como um método com alto grau de neuroproteção na hipóxia-isquemia (HI). OBJETIVO: verificar a potencialidade terapêutica da hipotermia como tratamento da encefalopatia hipóxico-isquêmica em recém-nascidos. MÉTODO: foram consultadas as bases de dados do Medline, Lilacs, Scielo e JCR-ISI. As consultas incluíram artigos registrados entre 1993 e 2008 no idioma Português, Inglês e Espanhol. DISCUSSÃO: encefalopatia hipóxico- isquêmica neonatal é complicação imediata à asfixia grave e pode causar graus variados de dano cerebral. As características do dano hipóxico isquêmico indicam que existe um período intermediário, em que é possível intervir interrompendo a cadeia de eventos que levam a destruição celular definitiva. Com a finalidade de proteger o cérebro dos insultos isquêmicos, utilizam-se drogas e diferentes procedimentos, tais como manitol, removedores de radicais livres, antagonistas de receptores opiáceos, supressores de metabolismo e hipotermia para minimizar as lesões. CONCLUSÃO: o resfriamento cerebral é a conduta terapêutica promissora em reduzir danos cerebrais em recém-nascidos.

INTRODUCTION: The nutritional needs and particularly, the energetic metabolism in childhood is a controversy in the literature. OBJECTIVE: To characterize the energetic spent at rest in children with sepsis. METHOD: The database of Medline and SciELO was consulted. We used as search strategy the words: newborn and energy spent or sepsis in all fields. RESULTS: In the case of sepsis , the child presents immaturity of the enzymatic system, which limits the production of some aminoacids, such as cystein (cistationase enzyme deficit in preterm), taurine, gutamine and nucleotides as coline e inositol. This fact turns those nutrients conditionally essential for children. CONCLUSION: Many concepts for adults are used in childohood, which is not correct and may cause several consequences to the health of children.