Hemodynamic effect of human and sheep atrial extract in anesthetized rats

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Hemodynamic effect of human and sheep atrial extract in anesthetized rats

Ranjbar A.¹, Nematbakhsh M.²

¹Department of Physiology, Jahrom School of Medical Sciences, Jahrom, Iran ²Department of Physiology, School of Medicine, Isfahan University, Isfahan, Iran

The structure of atrial natriurtic peptide (ANP) and Brain natriuretic peptide (BNP) are similar and they are also similar in their actions e.g natriuresis and vasodilation. The previous studies have revealed the presence of ANP and BNP in sheep atrial extract, wherease ANP in human atrial. The aim of the present study is to investigate the comparison of hemodynamic effects of these two atrial extracts on blood pressure and hematocrit in anesthetized rat.

Human and sheep atrial extract were prepared using with saline and acid millieu method. Male rats were anesthetized by pentobarbital (60 mg/kg, i.p.). Femoral artery and jugular vein were cannulated for recording blood pressure and drug administration respectively. To measure the hematocrit, blood samples were collected from eye at the beginning and 45 minutes after extract administration.

The rat mean arterial blood pressure (MAP) was reduced by sheep atrial extracts (p<0.05), whereas human atrial extract did not have any effect on MAP significantly. The hypotensive effect of sheep atrial extract was higher than the human extract (p<0.05). Both extracts increased the rat hematocrit significantly (P<0.05).

The obtained results indicate that different in hemodynamic effect of two extracts can be due to difference in ANP and BNP clearance, cardiac output fell and negative feedback inhibition.