Role of ventral medullary catecholaminergic neurons for respiratory modulation of sympathetic outflow in rats

Abstract Sympathetic activity displays rhythmic oscillations generated by brainstem inspiratory and expiratory neurons. Amplification of these rhythmic respiratory-related oscillations is observed in rats under enhanced central respiratory drive or during development of neurogenic hypertension. Herein, we evaluated the involvement of ventral medullary sympatho-excitatory catecholaminergic C1 neurons, using inhibitory Drosophila allatostatin receptors, for the enhanced expiratory-related oscillations in sympathetic activity in rats submitted to chronic intermittent hypoxia (CIH) and following activation of both peripheral (hypoxia) and central chemoreceptors (hypercapnia). Pharmacogenetic inhibition of C1 neurons bilaterally resulted in reductions of their firing frequency and amplitude of inspiratory-related sympathetic activity in rats in normocapnia, hypercapnia or after CIH. In contrast, hypercapnia or hypoxia-induced enhanced expiratory-related sympathetic oscillations were unaffected by C1 neuronal inhibition. Inhibition of C1 neurons also resulted in a significant fall in arterial pressure and heart rate that was similar in magnitude between normotensive and CIH hypertensive rats, but basal arterial pressure in CIH rats remained higher compared to controls. C1 neurons play a key role in regulating inspiratory modulation of sympathetic activity and arterial pressure in both normotensive and CIH hypertensive rats, but they are not involved in the enhanced late-expiratory-related sympathetic activity triggered by activation of peripheral or central chemoreceptors

Equilíbrio nutricional e distúrbios fisiológicos em manga 'Tommy Atkins' Nutritional balance and physiological disorders in mango 'Tommy Atkins'

Com o objetivo de avaliar o efeito do equilíbrio nutricional sobre a incidência de distúrbios fisiológicos em manga 'Tommy Atkins' cultivada no Vale do São Francisco, realizou-se um ensaio com frutos coletados no estádio de maturação fisiológica, classificados em frutos sem sintomas e com sintomas de distúrbio fisiológico. Os frutos das duas classes foram separados em casca, polpa e caroço, e levados para secagem em estufa a 65 &deg;C. Este material foi submetido a mineralização para a determinação das concentrações de N, K, Ca, Mg e B. Antes da desidratação, uma parte da polpa foi separada para as determinações do teor de sólidos solúveis totais (SST) e da acidez total titulável (ATT). Os resultados permitem concluir que, tanto as concentrações elevadas de Ca e Mg, como as baixas relações N/Ca e K/Ca, tanto na polpa quanto na casca, foram eficientes na prevenção de distúrbios fisiológicos nos frutos de mangueira; a concentração de nutrientes obtida na casca pode refletir melhor a condição da fisiopatia do que a concentração dos nutrientes na polpa dos frutos; os valores de SST e a relação SST/ATT determinada nos frutos com sintomas foram muito mais elevados do que nos frutos sem sintomas, devido a uma sobrematuração desordenada dos tecidos da polpa.<br>With the objective of evaluating the effect of the nutritional balance on the incidence of physiological disorders in mango cv. Tommy Atkins, grown in São Francisco River Valley, a trial was carried out with fruits harvested at physiological ripening stage, classified as fruits without and with physiological disorder symptoms. From all of them, skin, flesh and pit were separated and dried in a stove at 65ºC. This material was mineralized in order to determine N, K, Ca, Mg and B contents. Before dehydration, part of the flesh was taken for estimation of the total soluble solids (TSS) and total titrable acidity (TTA). The results allow to conclude that: high concentrations of Ca and Mg , as well as low ratios N/Ca and K/Ca, both in the flesh and in the skin, were efficient to prevent physiological disorders in mango fruits; the nutrient concentration in the skin may show better the condition of physiological disorders than the nutrient concentration in fruit flesh; and the TSS values and TSS/TTA ratio in fruits with symptoms were much higher than in fruits without symptoms, due to over ripening of flesh tissues

Suplementos energéticos para recria de novilhas de corte em pastagens anuais: desempenho animal Energy supplements for beef heifers rearing at annual pastures: animal performance

Foi avaliado o desempenho de novilhas de corte dos três aos doze meses de idade, mantidas em pastagem cultivada logo após o desmame (experimento 1) e no primeiro inverno pós-desmame (experimento 2), com ou sem o fornecimento de suplementos energéticos. No período de 16/02 a 21/04/2001, as novilhas permaneceram em pastagem de milheto, exclusivamente sob pastejo (PAST1), suplementadas com grão de milho moído (PAST1/M) ou com polpa cítrica peletizada e moída (PAST1/P). No período de 13/07 a 09/10/2001, as novilhas foram mantidas em pastagem de aveia preta e azevém, sem suplementação (PAST2), suplementadas com grão de milho moído (PAST2/M) ou suplementadas com casca de soja (PAST2/C). Peso vivo (PV), ganho de peso diário médio (GDM) e escore de condição corporal (ECC) foram avaliados. No experimento 1, os animais suplementados apresentaram maior PV final, GDM e ECC que os não-suplementados, não diferindo entre si. No experimento 2, as novilhas suplementadas com casca de soja apresentaram maior GDM e PV final que as não-suplementadas, enquanto as suplementadas com grão de milho ficaram em posição intermediária. O maior ECC foi obtido pelos animais de PAST2/C, seguidos de PAST2/M e, por último, de PAST2. Novilhas de corte desmamadas aos 60-90 dias devem ser suplementadas no período inicial pós-desmama, para que atinjam desenvolvimento satisfatório nesta fase do crescimento. Os subprodutos polpa cítrica e casca de soja podem substituir o grão de milho como suplementos energéticos para recria de novilhas de corte.<br>It was evaluated beef heifers performance from three until twelve months of age, when they were reared in cultivated pasture soon after their weaning (experiment 1) and in the first winter post-weaning (experiment 2), with or without the supply of energy supplements to the animals. From 02/16 to 04/21/2001, the heifers stayed in Pearl Millet pasture, exclusively under grazing (PAST1); supplemented with milled corn grain (PAST1/C) or supplemented with pellet citric pulp (PAST1/P). From 07/13 to 10/09/2001, the heifers were maintained in oat plus italian ryegrass pasture without supplementation to the animals (PAST2); supplemented with milled corn grain (PAST2/C) or supplemented with soy hull (PAST2/H). The evaluated variables of animal performance were live weight (LW), average daily gain (ADG) and body condition score (BCS). In the experiment 1, supplemented animals presented larger values of final LW, ADG and BCS in relation to the non supplemented, ones the supplemented treatments not differing to each other. In experiment 2, the soy hull supplemented heifers showed greater ADG and final LW than non supplemented heifers, with the corn grain supplemented group in an intermediary position. The highest BCS was obtained by the animals of PAST2/H, followed by PAST2/C and, at last, of PAST2. Beef heifers weaned at 60-90 days should be supplemented in the initial post-weaning period, enabling them to reach satisfactory development in this phase of growth. The by-products citric pulp and soy hull can substitute the corn grain as energy supplements for rearing of beef heifers