RESUMO
It is known that atrial natriuretic peptide [ANP] plays a major role in the homeostasis of body fluids. There are evidence that ANP may link the heart, kidney, adrenal, blood vessels and brain in a complex system involved in the regulation of body fluids and electrolytes as well as blood pressure. The study was carried out on 90 male albino rats divided into 6 groups, each of 15 rats. The first group was kept for 15 days on normal diet [controls], the 2nd, 3rd groups were kept on different sodium intake, 50, 150 and 350 nmol/kg of diet respectively. The 5th group was injected daily with 0.01 micro l/kg body weight ANP and the last group was injected daily with 0.02 micro l/kg body weight cafedrine HC1, theodrenaline HC1 for 7 days. At the end of the experiments the animals were sacrificed, blood samples were obtained and plasma separated and kept frozen for analysis. The results show that plasma ANP, renin, aldosterone and angiotensin II were significantly decreased in the 3rd, and 4th groups while in the 2nd group there was no statistically significant change when compared with controls. After injection of cafedrine, HC1, theodrenaline HC1, plasma ANP was significantly decreased while plasma renin, aldosterone and angiotensin II were significantly increased. After injection of ANP, significant decrease in renin and aldosterone was observed but angiotensin II showed significant decrease. Plasma sodium and potassium concentrations were significantly increased in all cases compared to controls. The results were discussed according to current literatures