Hemorrhage effects on plasma ANP, NH2-terminal pro-ANP, and pressor hormones in anesthetized and conscious rats.
We examined the effect of hemorrhage on plasma NH2-terminal pro-atrial natriuretic peptide (NT-pro-ANP) and atrial natriuretic peptide (ANP) in anesthetized and conscious rats. Blood (1.5 ml/time point) was withdrawn at 0, 10, 20, and 30 min. In anesthetized rats it caused decrease in mean arterial pressure and led to bradycardia in 2 min. Right atrial pressure decreased significantly after 12 min. However, plasma ANP did not change, and NT-pro-ANP actually increased from 481 +/- 55 to 609 +/- 73 pmol/l (P < 0.01) at 20 min and to 696 +/- 82 pmol/l (P < 0.01) at 30 min. Also plasma arginine-8-vasopressin (AVP) and epinephrine increased significantly at 30 min. No significant changes in plasma endothelin and norepinephrine were found. The increase in NT-pro-ANP after hemorrhage was not blocked by AVP V1-receptor, alpha- and beta-catecholaminergic receptor, or muscarinic-receptor antagonists. The plasma 125I-ANP disappearance curve was shifted to the right after hemorrhage in anesthetized rats, suggesting that the elimination of ANP was decreased. In conscious rats, heart rate and right atrial pressure did not change significantly after hemorrhage, and mean arterial pressure did not decrease until 22 min. NT-pro-ANP decreased from 1,467 +/- 146 to 1,072 +/- 130 pmol/l (P < 0.01) at 20 min and to 941 +/- 41 pmol/l (P < 0.01) at 30 min. Plasma ANP did not respond to hemorrhage in conscious rats. In conclusion, we found no change in plasma ANP during hemorrhage in either anesthetized or conscious rats, but we did find a significant increase in plasma NT-pro-ANP levels in anesthetized rats and a significant decrease in conscious rats. We suggest that this divergence may be due to different hemodynamic responses to hemorrhage.
Leskinen
H
H
Department of Physiology, University of Oulu, Finland.
Ruskoaho
H
H
Huttunen
P
P
Leppäluoto
J
J
Vuolteenaho
O
O
D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D009320:Atrial Natriuretic Factor / Q000097:blood* / Q000737:chemistry; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000502:physiology*; D002319:Cardiovascular System / Q000503:physiopathology; D006470:Hemorrhage / Q000097:blood* / Q000503:physiopathology; D006728:Hormones / Q000097:blood*; D008297:Male; D011498:Protein Precursors / Q000097:blood* / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D013565:Sympatholytics / Q000494:pharmacology
D065092:Antidiuretic Hormone Receptor Antagonists; D006728:Hormones; D011498:Protein Precursors; D013565:Sympatholytics; D001285:Atropine; D009320:Atrial Natriuretic Factor