The influence of acute blood volume changes on plasma renin activity in man

The effect of an acute 10% blood volume reduction on plasma renin activity (PRA) was examined in seven patients with minor heart diseases during haemodynamic investigation and in five healthy subjects after 3 days furosemide administration. PRA was not significantly changed. Blood pressure remained constant, atrial pressures decreased. The effect on PRA of an acute 10% blood volume expansion with albumin infusion was studied in thirteen patients with liver or heart diseases. A slight reduction of PRA after albumin did not exceed the expected decrease due to plasma dilution. Blood pressure was unchanged, atrial pressures increased. Renal blood flow increased after albumin in all of the five patients investigated. The effect of PRA of an acute 10% blood volume expansion with whole blood flow increased after albumin in all of the five patients investigated. The effect on PRA of an acute 10% blood volume expansion with whole blood was then investigated in five healthy subjects, pretreated with furosemide for 3 days. A significant decrease in PRA was found. Blood pressure remained constant. It is concluded that an acute blood loss of 10% and an acute blood volume expansion of 10% with albumin have little influence on PRA in supine man, whereas an acute blood volume expansion of 10% with whole blood induces a significant PRA suppression.