Myocardial actions of the vasodilator peptide adrenomedullin (ADM) in the intact animal are unknown. Negative and positive inotropic actions have been reported in ex vivo experiments. Myocardial and load-altering actions of ADM in dogs before and after development of heart failure were studied. With controlled heart rate (atrial pacing) and after β-blockade, ADM was administered to five normal dogs in doses of 20 ng·kg-1·min-1 iv, 100 ng·kg-1·min-1 iv, and 200 ng·kg-1·min-1 into the left ventricle (LV). LV peak systolic pressure and end-systolic volume decreased with each dose of ADM. End-systolic pressure decreased with the two higher doses. At the highest dose, arterial elastance and the time constant of LV isovolumic relaxation (τ) decreased, and LV end-systolic elastance (E(es)) increased. LV end-diastolic pressure and volume were unchanged. In five additional normal dogs receiving only the highest dose of ADM (200 ng·kg-1·min-1 intra-LV), to control for increased heart rate and sympathetic activation observed with the cumulative infusion, ADM produced arterial vasodilation but no change in E(es) or τ. In four dogs with pacing-induced heart failure, ADM (200 ng·kg-1·min-1 intra-LV) was without effect on τ, E(es), and systolic or diastolic pressure and volume. In vivo, ADM appears to be a selective arterial dilator without inotropic or lusitropic effects. The vasodilatory actions are attenuated in heart failure.
|Original language||English (US)|
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|Issue number||3 48-3|
|State||Published - 2000|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)