Alterations in circulating and cardiac tissue concentrations of brain natriuretic peptide in spontaneously hypertensive rats.
OBJECTIVE
This study was designed to investigate the modification of plasma and cardiac tissue brain natriuretic peptide concentrations in spontaneously hypertensive rats and Wistar-Kyoto rats in relation to those of atrial natriuretic peptide during the development of hypertension.


METHODS
Blood pressure, tissue weight, and plasma and cardiac tissue atrial natriuretic peptide and brain natriuretic peptide concentrations were measured in conscious 5, 10, and 18 week old, spontaneously hypertensive, and in corresponding normotensive rats. Pharmacokinetics of atrial natriuretic peptide and brain natriuretic peptide were also examined.


RESULTS
Plasma concentrations of both atrial natriuretic peptide and brain natriuretic peptide in hypertensive rats increased significantly with development of hypertension. The pattern was not in parallel, so that the brain natriuretic peptide/atrial natriuretic peptide ratio was high in spontaneously hypertensive rats. Concentrations of brain natriuretic peptide in the cardiac ventricle were already higher in hypertensive rats than in controls as early as 5 weeks of age, whereas atrial natriuretic peptide concentrations in the ventricle, predominantly in the left ventricles, and the highest brain natriuretic peptide/atrial natriuretic peptide ratio was in the left ventricles from 18 week old spontaneously hypertensive rats. Pharmacokinetics showed that the plasma half lives of atrial natriuretic peptide and brain natriuretic peptide were not different between the two strains.


CONCLUSIONS
Although raised blood pressure stimulates both atrial natriuretic peptide and brain natriuretic peptide, production of brain natriuretic peptide in the ventricles is already increased in the prehypertensive stage, and in older hypertensive rats, it is more responsive to progression of hypertension than atrial natriuretic peptide. It is suggested that regulation of production and secretion of the two natriuretic peptides is not temporally coordinated during development of hypertension in this model.
Yokota
N
N
First Department of Internal Medicine, Miyazaki Medical College, Japan.
Yamamoto
Y
Y
Kitamura
K
K
Kangawa
K
K
Minamino
N
N
Matsuo
H
H
Eto
T
T
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics; D006207:Half-Life; D006973:Hypertension / Q000097:blood / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D009419:Nerve Tissue Proteins; D020097:Natriuretic Peptide, Brain; D009320:Atrial Natriuretic Factor