EFEIFOS DO SULFATE DE MAGNESIO NA HEMODINAMICA CARDIOVASCULAR DE CAES ANESTESIADOS COM PENTOBARBITAL SODICO

Background and Objectives - A controversy exists in the literature regarding the effects of the acute administration of magnesium on the cardiovascular system of animals and humans. The purpose of this study was to evaluate the effects of hypermagnesemia on the cardiovascular hemodynamics of dogs. Methods - Sixteen mongrel dogs were anesthetized with pentobarbitone 30 mg.kg-1 and submitted to volume expansion with Ringer's solution (0.4 ml.kg-1.min-1 and mechanical ventilation with room air. In this model, the hemodynamic repercussions of the following drugs and doses were studied. pentobarbitone 5 mg.kg-1 Group 1, control - and the association of pentobarbitone and magnesium sulphate (MS), at the dose of 140 mg.kg-1 injected in 15 minutes, followed by an infusion of 80 mg.kg-1.h-1 - Group 2. The parameters studied were: heart rate, blood pressure, inferior vena cava pressure, cardiac index, systolic index and peripheral resistance index, evaluated at 5 different moments: 15(M1), 30(M2), 60(M3) and 75(M4) minutes after the first suppplementary dose of pentobarbitone and 15 minutes (M5) after the second supplementary dose. In Group 2, the moments M3, M4, M5 corresponded to 15, 30 and 60 minutes after the priming dose of magnesium sulphate. Results - Group 1 animals exhibited tachycardia since the beginning of the experiment. There was a decrease in the cardiac index, in the systolic index and an increase in the inferior vena cava pressure. Group 2 animals also exhibited tachycardia, but heart rate decreased after MS infusion. The blood pressure and the peripheral resistance index decreased. The systolic index increased and the cardiac index decreased only at the end of the experiment. Conclusions: The antiadrenergic effects of MS could have been responsible for the decrease in heart rate. The vasodilating effects of the magnesium induced the decrease in the peripheral resistance index. The systolic index increased, showing that myocardial depression did not occur.

EFEITOS DO SULFATE DE MAGNESIO NA HEMODINAMICA E FUNCAO RENAL DE CAES ANESTESIADOS CORN PENTOBARBITAL SODICO

Background and objectives - The use of magnesium sulphate for the prevention of seizures in pre-eclampsia may induce hypermagnesemia. Clinical and experimental studies are not in agreement about the effects of magnesium on the renal hemodynamics and function. We therefore studied the effects of hypermagnesemia on the renal hemodynamics and function of dogs anesthetized with pentobarbitone. Methods - Sixteen mongrel dogs were anesthetized with pentobarbitone 30 mg.kg-1 and submitted to extracellular ) and mechanical ventilation with room air. The dogs were volume expansion with Ringer's solution (0.4 ml.kg.min allocated into two groups of 8 animals, for the study of renal hemodynamics and function following the administration of 5 mg.kg-1 of pentobarbitone (Group 1 - control or of pentobarbitone associated with magnesium sulphate in the dose (Group 2). The parameters studied were: PAH of 140 mg.kg, administered in 15 minutes, followed by 80 mg.kg-1.h-1 clearance, creatinine clearance, osmolar clearance, free water clearance, renal blood flow, renal vascular resistance, filtration fraction, urinary volume, plasmatic and urinary osmolarity, urinary and fractionary excretion of sodium and potassium, measured at five moments: 15 (M1), 30 (M2), 60 (M3) and 75 (M4) minutes after the first supplementary dose of pentobarbitone and 15 minutes (M5) after the second supplementary dose in Group 1. In Group 2, the moments M3, M4, M5 were 15, 30 and 60 minutes after the priming dose of magnesium sulphate and during the maintenance dose. Results - In Group I no significant changes were observed in renal hemodynamic parameters and creatinine clearance. The extracellular volume expansion increased urinary volume and decreased urinary osmolarity as a consequence of sodium, potassium and free water clearance. The fractionary excretion of sodium was maintained. The plasmatic osmolarity increased. In Group 2, renal hemodynamic parameters and creatinine clearance were also maintained. There was an increase in renal sodium clearance, as detected by the increase in the fractionary excretion of sodium. Conclusions - Magnesium sulphate did not produce significant changes in renal hemodynamics and facilitated the renal excretion of sodium in dogs anesthetized with pentobarbitone.

Hydrothermal rare earth elements mineralization in the Barra do Itapirapua carbonatite, southern Brazil: behaviour of selected trace elements and stable isotopes (C, O)

The Bura do Itapira pua carbonatite is located in southern Brazil and belongs to the Cretaceous Ponta Grossa alkaline-carbonatitic province related to the opening of the South Atlantic. The carbonatite complex is emplaced in Proterozoic granites and is mainly composed of plutonic magnesio- to ferrocarbonatite, with smaller amounts of subvolcanic magnesiocarbonatite. Hydrothermal alteration of the carbonatite has led to the formation of quartz, apatite, fluorite, rue earth fluorocarbonates, barite and sulfides in variable proportions. Trace element data, delta(13)C and delta(18)O are presented here, with the aim of better understanding the geochemical nature of hydrothermal alteration related to rare earth elements (REE) mineralization. The non-overprinted plutonic carbonatite shows the lowest REE contents, and its primitive carbon and oxygen stable isotopic composition places it in the field of primary igneous carbonatites. Two types of hydrothermally overprinted plutonic carbonatites can be distinguished based on secondary minerals and geochemical composition. Type I contains mainly quartz, rare earth fluorocarbonates and apatite as hydrothermal secondary minerals, and has steep chondrite normalized REE patterns, with Sigma(REE+Y) of up to 3 wt.% (i.e., two orders of magnitude higher than in fresh plutonic samples). In contrast, the Type II overprint contains apatite, fluorite and barite as dominant hydrothermal minerals, and is characterized by heavy REE enrichment relative to the fresh samples, with flat chondrite normalized REE patterns. Carbon and oxygen stable isotope ratios of Types I and II are elevated (delta(18)O + 8 to + 12 parts per thousand; delta(13)C - 6 to - 2 parts per thousand) relative to the fresh samples. Hydrothermally overprinted carbonatites exposed to weathering show even higher delta(18)O values (delta(18)O 13 to 25 parts per thousand) but no additional REE enrichment. The subvolcanic carbonatite has anomalously high delta(13)C of up to + 1 parts per thousand, which suggests crustal contamination through interaction with carbonate-bearing metasediments. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Efeito da dieta com deficiência de magnésio sobre a manutenção da osseointegração de implantes de titânio: análise radiográfica, densitométrica e de torque reverso

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito da deficiência de magnésio na dieta sobre a densidade e o metabolismo ósseo ao redor de implantes com osseointegração estabelecida: estudos em ratos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Calagem, gessagem no preparo do solo e semeadura do algodoeiro com modos de adubação diferenciados, para a região de Selvíria/MS

Pós-graduação em Agronomia - FEIS

Petrologia aplicada da formação Corumbataí (região de Rio Claro - SP) e produtos cerâmicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Acúmulo de nutrientes e relação Ca:Mg no cultivo da cebola, no submédio São Francisco

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Enxertia, potássio e magnésio na nutrição, desenvolvimento e produção de pepino

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da deficiência de magnésio sobre o metabolismo do tecido ósseo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo da adição de dopantes a base de carbono nas propriedades anelásticas de MgB2

Pós-graduação em Ciência e Tecnologia de Materiais - FC