Vasopressin and angiotensin II contribute equally to the increased afterload in rabbits with heart failure.
OBJECTIVE
Vasopressin, like angiotensin, has both vasoconstrictor and fluid retaining properties and therefore may make an important contribution to the pathogenesis of low output congestive heart failure. The study aimed to examine the relative importance of the renin-angiotensin system and vasopressin in an animal model of heart failure.


METHODS
The acute haemodynamic effects of vasopressin receptor blockade with a selective antagonist, d(CH2)5DAVP (AVPA) (30 micrograms.kg-1) and angiotensin converting enzyme inhibition with captopril (1 mg.kg-1) were compared. The effect of combined blockade (ie, vasopressin receptor antagonist + angiotensin converting enzyme inhibitor) was also examined.


METHODS
Rabbits, 2.5-3.5 kg, with doxorubicin induced cardiomyopathy and heart failure (n = 20) were used. There were 15 controls.


RESULTS
Both AVPA and captopril produced significant increases in cardiac output (11% and 13% respectively) and falls in peripheral vascular resistance (21% and 17% respectively). Inhibition of the two vasoconstrictor systems was additive and resulted in a fall in peripheral vascular resistance to levels found in normal animals.


CONCLUSIONS
Vasopressin and angiotensin II make equal contributions to the raised peripheral vascular resistance observed in this model of heart failure. Vasopressin inhibition may be useful in the treatment of heart failure either alone or as an adjunct to angiotensin converting inhibition.
Arnolda
L
L
Melbourne University Department of Medicine, Austin Hospital, Victoria Australia.
McGrath
B P
BP
Johnston
C I
CI
D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002216:Captopril / Q000494:pharmacology; D002302:Cardiac Output / Q000187:drug effects; D004195:Disease Models, Animal; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D008297:Male; D011817:Rabbits; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014667:Vasopressins / Q000037:antagonists & inhibitors / Q000502:physiology*
D014667:Vasopressins; D000804:Angiotensin II; D001127:Arginine Vasopressin; C025044:argipressin, beta-mercapto-beta,beta cyclopentamethylenepropionic acid(1)-; D002216:Captopril