Natriuretic peptide responses to acute and chronic ventricular
pacing in sheep.
Rademaker, M T, C J Charles, Ea Espiner, Cm Frampton, Mg Nicholls, Am
Richards.
Department of Medicine, The Christchurch School of Medicine,
Christchurch, New Zealand
APStracts 2:0351H, 1995.
The responses of atrial natriuretic peptide (ANP) and brain
natriuretic peptide (BNP) were investigated in six conscious sheep
paced at: 120, 155, 190 and 225bpm for 1.5 hours at each rate; and at
180, 225 and 180bpm for 4 days at each rate. Increased pacing reduced
arterial pressure, cardiac output and urine and sodium excretion and
increased left atrial pressure and plasma ANP, BNP and C-type
natriuretic peptide (CNP), with delayed activation of the renin
-angiotensin system (RAS). Acute pacing increased plasma ANP and BNP
levels 8.6 and 3.6 fold respectively (both p<0.001), while
chronic pacing increased ANP and BNP 7.8 and 9 fold respectively
(both p<0.001). Thus, the ANP:BNP ratio increased during acute
pacing (p<0.001) and decreased proportionately during chronic
pacing (p<0.05). Reduction in pacing improved hemodynamic
status, reduced natriuretic peptides (BNP less than ANP), normalised
the RAS and induced diuresis and natriuresis. In conclusion, BNP is
less responsive than ANP to acute changes in intracardiac pressure,
but is proportionately more responsive to chronic hemodynamic changes
as occur in congestive heart failure.
Received 19 June 1995; accepted in final form 4 August 1995.
APS Manuscript Number H554-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.