Renal and hormonal responses to atrial natriuretic peptide and turtle atrial extract in the freshwater turtle, <i>Amyda japonica</i>

Abstract

Abstract The effects of synthetic atrial natriuretic peptide and turtle atrial extract on cardiovascular and renal functions were examined in the freshwater turtle, Amyda japonica . Both the atrium and ventricle of the turtle heart contained an immunoreactive atrial natriuretic peptide. Synthetic rat atrial natriuretic peptide (atriopeptin III) and turtle atrial extract caused a dose‐dependent decrease in mean arterial blood pressure. In turtles that received either atriopeptin III or turtle atrial extract, no significant changes in renal function were observed. However, furosemide was effective in altering renal function. Levels of aldosterone in plasma decreased after 2 hours and increased after 24 hours following injection of atriopeptin III, although the plasma renin concentration did not change. We suggest that the heart of the freshwater turtle may contain an immunoreactive atrial natriuretic peptide and that the atrial natriuretic peptide is more important in the regulation of blood pressure than in the regulation of renal function.