[Effects of peptides originated from the proadrenomedullin on the production of nitric oxide in rat aorta].
OBJECTIVE
To observe the effect of adrenomedullin (ADM) on the production of nitric oxide (NO) in rat aorta and the effect of Proadrenomedullin N-terminal 20 peptide (PAMP) and adrenotensin (ADT) on the ADM-induced NO production.


METHODS
Isolated aortic tissues were exposed to ADM, PAMP and ADT for 2 h. The NO production, indicated by nitrite content in the incubated media, and the nitric oxide synthase (NOS) activity in the incubated tissues were assayed.


RESULTS
Nitrite productions and NOS activities of the aortic tissues were significantly increased by ADM in a concentration-dependent manner. The nitrite production and NOS activity of the aortic tissues stimulated by ADM (10(-8) mol.L-1) incubation were (0.282 +/- 0.046) mumol per mg protein and (0.323 +/- 0.056) pmol.min-1 per mg protein, respectively, which were greater than those of the control (0.173 +/- 0.026) mumol per mg protein and (0.110 +/- 0.028) pmol.min-1 per mg protein (P < 0.01), respectively. The nitrite production and NOS activity were (0.204 +/- 0.049) mumol per mg protein and(0.178 +/- 0.023) pmol.min-1 per mg protein when the tissues were treated with ADM (10(-8) mol.L-1) and PAMP (10(-8) mol.L-1) in combination, and were (0.150 +/- 0.036) mumol per mg protein and (0.123 +/- 0.031) pmol.min-1 per mg protein when ADM (10(-8) mol.L-1) and ADT (10(-8) mol.L-1) were used in combination, which were significantly less than those in ADM (10(-8) mol.L-1) group. After incubation of the aortic tissues with the same concentrations(10(-8) mol.L-1) of ADM, PAMP and ADT in combination, the nitrite production and NOS activity were (0.162 +/- 0.029) mumol per mg protein and (0.110 +/- 0.024) pmol.min-1 per mg protein, which were also greatly reduced as compared with those of the ADM group (10(-8) mol.L-1, P < 0.01). However, neither PAMP nor ADT had effect on the production of nitrite and NOS activity in the aortic tissues.


CONCLUSIONS
ADM enhanced the NO production in rat aorta, which was antagonized by PAMP and ADT alone or in combination through influencing the NOS activity.
Dong
Xianhong
X
Department of Physiology and Pathophysiology, Peking University School of Basic Medical Science, Beijing 100083, China.
Li
Juxiang
J
Zhong
Guangzhen
G
Ren
Yongsheng
Y
Wu
Shengying
S
Tang
Chaoshu
C
D053607:Adrenomedullin / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats
D010446:Peptide Fragments; C094997:adrenotensin; D053607:Adrenomedullin; D009569:Nitric Oxide