DEPARTMENT OF PHYSIOLOGY, JAHROM SCHOOL OF MEDICAL SCIENCES, OSTAD MOTAHHARI STREET, JAHROM IRAN
Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Background-Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) belong to a family of hormones that have structural similarities and some biological actions in common, such as natriuresis and vasodilatation. Previous studies have revealed the presence of ANP and BNP in the sheep atrial extract and ANP in the human atrium. The aim of the present study was to compare the hemodynamic effects of the two atrial extracts on blood pressure and hematocrit in anesthetized rats.
Methods- Human and sheep atrial extracts were prepared using saline and acid milieu method.
The femoral arteries and jugular veins were cannulated for recording blood pressure and drug administration, respectively. To measure the hematocrit, we collected blood samples from the rats' eyes at the beginning and once again after 45 minutes of extract administration.
Result- The rats' mean arterial blood pressure (MAP) was reduced by the sheep atrial extract (p<0.05), whereas the human atrial extract did not have any significant effect on MAP. The hypotensive effect of the sheep atrial extract was higher than that of the human extract (p<0.05). Both extracts increased the rats' hematocrit significantly (P<0.05).
Discussion- The obtained results suggest that the difference between the hemodynamic effects of the two extracts could be due to the differences between the ANP and BNP clearance, cardiac output fall and the negative feedback inhibition.