CARDIOVASCULAR EFFECTS OF CENTRAL CLONIDINE IN CONSCIOUS RATS AFTER HYPOTHALAMIC-LESIONS

The central injection of clonidine (an alpha-2-adrenoceptor agonist) in conscious normotensive rats produces hypertensive responses and bradycardia. The present study was performed to investigate the effect of electrolytic lesions in the anteroventral third ventricle (AV3V) region or in the lateral hypothalamus (LH) on the pressor and bradycardic responses induced by central clonidine in rats. Mean arterial pressure and heart rate were recorded in sham or AV3V-lesioned rats with cerebral stainless steel cannulae implanted into the lateral cerebral ventricle (ICV) or LH. and in sham or bilateral LH-lesioned rats with cannulae-implanted ICV. The injection of clonidine (40 nmol) ICV or into the LH of sham rats produced a pressor response (37 +/- 2-48 +/- 3 mmHg) and bradycardia (-45 +/- 10--93 +/- 6 bpm). After AV3V-lesion (3 and 12 days) or LH-lesion (3 days) the pressor response was abolished and a small hypotensive response was induced by the injection of clonidine (-1 +/- 3--16 +/- 3 mmHg). The bradycardia (-27 +/- 6--57 +/- 11 bpm) was reduced, but not abolished by the lesions. These results show that the AV3V region and LH are important cerebral structures that participate in the excitatory pathways involved in the pressor response to central clonidine in rats. They also suggest that, in the absence of these pressor pathways, the hypotensive responses to central clonidine may appear in conscious rats.

Effects of central alpha-adrenergic agonists on hormone-induced 3% NaCl and water intake

Male rats received intracerebroventricular (ICV) renin (600 ng) or daily subcutaneous injections of deoxycorticosterone (5 mg) to induce 3% NaCl and water intake. Noradrenaline (NOR; 40-160 nmol) and clonidine (CLO; 5-20 nmol) injected ICV. induced 70 to 100% inhibition of the intakes. Phenylephrine (PHE; 40-160 nmol) injected ICV induced 60 to 95% inhibition of the intakes. NOR and PHE induced a stronger inhibition on the 3% NaCl intake induced by renin than on the intake induced by deoxycorticosterone (DOC), and CLO did the opposite. CLO was always more effective than PHE to induce inhibition of the intakes. The results suggest that NOR inhibits hormone (angiotensin II, aldosterone)-induced NaCl intake by acting mainly on alpha(2)-adrenergic receptors.

Post-fire succession of small mammals in the Cerrado of central Brazil

In the Cerrado savannas from Brazil fire events are common and strongly influence the vegetation structure and, consequently, the associated small mammals. In this paper, we investigate changes in the structure of small mammal communities related to sites of different post-fire ages. Mammals were captured in similar Cerrado sites that differed in time since the last burn ( 1 to 26 yr). We sampled six sites in the wet season of 1997 ( phase 1) and, three years later, six sites in the wet and dry seasons ( phase 2). Six rodent species and four marsupials were captured. Community composition changed drastically as a function of time since fire. The diversity and abundance of small mammals reached maximum values in the early successional stages. The rodent Calomys tener was present only in early seral stages. The rodent Bolomys lasiurus was more frequent in mid-successional stages and decreased in later seral stages, and the rodent Oryzomys subflavus occupied all successional stages. The marsupial Gracilinanus agilis was dominant in the area that did not burn for at least 23 yr. Changes in composition of the community of small mammals were more accelerated in early successional stages, when there are more drastic vegetational changes. The ability of small mammals to cope with Cerrado fires and the great dissimilarity among post-burning seral stages suggest that a mosaic of areas representing different post-fire seral stages could increase the regional diversity of this group.

The neuranatomical basis of central control of cardiorespiratory interactions in vertebrates

It seems that a dual location for vagal preganglionic neurones (VPNs) has important functional correlates in all vertebrates. This may be particularly the case with the central control exerted over the heart by cardiac VPNs (CVPNs). About 30 % of VPNs but up to 70 % of CVPNs are in the nucleus ambiguus (NA) of mammals. There is a similar proportional representation of VPNs between the major vagal nuclei in amphibians and turtles but in fish and crocodilians; the proportion of VPNs in the NA is closer to 10% and in some lizards and birds it is about 5%. However, the CVPNs are distributed unequally between these nuclei so that 45 % of the CVPNs are located in the NA of the dogfish, and about 30% in the NA of Xenopus and the duck. This topographical separation of CVPNs seems to be of importance in the central control of the heart. Cells in one location may show respiration-related activity (e.g those in the dorsal vagal nucleus (DVN) of dogfish and in the NA of mammals) while cells in the other locations do not. Their different activities and separate functions will be determined by their different afferent inputs from the periphery or from elsewhere in the CNS, which in turn will relate to their central topography. Thus, CVPNs in the NA of mammals receive inhibitory inputs from neighbouring inspiratory neurones, causing respiratory sinus arrythmia (RSA), and the CVPNs in the DVN of the dogfish may generate cardiorespiratory synchrony (CRS).

A GEOGRAPHICAL REPRESENTATION IN Coats of arms of LATIN AMERICA

This article seeks to reflect on geographic representation in the coats of arms of countries in Latin America, showing how the physical, aspects of the landscape, the elements of the economy and the republican symbols were used by local elites to compose an imaginary nation in the nineteenth century. This process of "naturalization of territory" was used as an important feature in the national discourse, because this time, in most cases, the Latin American nations were composed of multi-ethnic states, with strong differences of class and a large illiterate population plus a very tenuous territory from the point of view of national integration. Thus, the elements related to geographic image through the use of coats of arms, conveyed strong messages to citizens, showing how these heraldic symbols can become an important source of research to unravel the process of building the imaginary nation.

Anuario Estadístico de América Latina y el Caribe 2005 = Statistical Yearbook of Latin America and the Caribbean 2005

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Anuario Estadístico de América Latina y el Caribe 2007 = Statistical Yearbook of Latin America and the Caribbean 2007

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Anuario Estadístico de América Latina y el Caribe 2008 = Statistical Yearbook of Latin America and the Caribbean 2008

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Anuario Estadístico de América Latina y el Caribe 2009 = Statistical Yearbook of Latin America and the Caribbean 2009

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Anuario Estadístico de América Latina y el Caribe 2010 = Statistical Yearbook of Latin America and the Caribbean 2010

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Anuario Estadístico de América Latina y el Caribe 2011 = Statistical Yearbook of Latin America and the Caribbean 2011

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Anuario Estadístico de América Latina y el Caribe 2012 = Statistical Yearbook of Latin America and the Caribbean 2012

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