Effects of intracerebroventricular infusion of angiotensin II and related peptides on water and sodium ingestion and excretion

The objetive of the present study was to investigate the effects of an angiotensin II (AII) analogue, Des-Asp1-AII and of two competitive blockers, [Leu8]-AII and [octanoyl-Leu8]-AII, infused intracerebroventriculary on the ingestion of water and of a 3% NaCl solution, as well as on diuresis and natriuresis in normal rats and in adrenalectomized and deoxycorticosterone (DOCA)-treated rats. Both AII and Des-Asp1-AII increased water and 3% NaCl intake and increased urine and Na+ excretion, the effect of AII being more intense. Except for 3% NaCl, the responses of all other parameters were totally or partially reduced by previous treatment with [Leu8]-AII or [octanoyl-Leu8]-AII. Subcytaneous DOCA injection caused water ingestion. Previous treatment with DOCA increased the response to AII for the ingestion of 3% NaCl and inhibited sodium excretion. The results obtained for adrenalectomized rats treated with DOCA, AII and analogous agonists did not differ from those observed in normal rats. These data suggest a possible synergism between the cerebral and renal renin-angiotensin systems in the regulation of the physiological parameters studied

Effect of atropine injection into the medial septal area on food-associated drinking

The effect of atropine injection into the medial septal area (MSA) or medial preoptic area (MPOA) on carbachol-induced drinking was evaluated in conscious unrestrained rats during a food-associated drinking test reinforced by 14 h of food deprivation. Atropine did not alter food intake when injected into either area, nor did it affect drinking after its injection into the MPOA. However, atropine markedly reduced water intake after its injection into the MSA. These results suggest that the central cholinergic system in the MSA can participate in the regulation of food-associated drinking

Homeostase e organizaçäo: relaçäo entre os conceitos e introduçäo do tempo / Homeostasis and organization: relationship between concepts and introduction of time

Este artigo, de caráter introdutório, discute e revê algumas idéias a respeito do conceito de homeostase. Fatos e modelos temporais säo introduzidos para mostrar que existem mudanças de estado nos biossistemas que näo säo preditas pela homeostase. Conceitos de termodinâmica e de organizaçäo säo apresentados, fornecendo novas bases para se entender o estado de um biossistema