Enhancement of coronary conductance by alpha-human atrial natriuretic polypeptide without effects on myocardial contractility.
The effect of synthetic human atrial 28-amino acid peptide (alpha-human atrial natriuretic polypeptide, alpha-hANP) on coronary circulation and cardiac functions was examined in open-chest dogs. Intravenous injection of alpha-hANP increased coronary and systemic conductance, and coronary and aortic blood flow with a significant fall in blood pressure. Continuous infusion of alpha-hANP into the left anterior descending coronary artery (LAD) increased LAD blood flow in a dose-dependent manner. The linear regression analysis revealed the relationship of logit (changes in mean coronary conductance (delta MCC] = 1.45 x log (coronary plasma concentration of alpha-hANP) + 7.51 (r = 0.87, n = 29). REC50 of alpha-hANP was 5.1 microM, where REC50 was the concentration to increase MCC to a half maximum MCC during reactive hyperemia after a 30-s coronary occlusion. alpha-hANP increased coronary conductance with no changes of myocardial oxygen consumption (MVO2) when blood pressure remained constant. Indices of myocardial contractility measured with a strain gauge arch, myocardial force (F), max dF/dt and LV max dp/dt, were not altered by either bolus intravenous injection or continuous intracoronary infusion of alpha-hANP. These results indicated a direct increase by alpha-hANP of coronary and systemic vascular conductance.
Shimizu
A
A
First Department of Internal Medicine, Okayama University Medical School, Japan.
Ueeda
M
M
Watanabe
H
H
Hina
K
K
Yamada
N
N
Kusachi
S
S
Saito
D
D
Haraoka
S
S
Tsuji
T
T
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000008:administration & dosage / Q000494:pharmacology*; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D007261:Infusions, Intra-Arterial; D007275:Injections, Intravenous; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D012044:Regression Analysis
D009320:Atrial Natriuretic Factor