V1 receptor activation induced by hemorrhage and sympathoinhibition in the mesentery and hindquarters of spontaneously hypertensive rats.
Hiroshima J Med Sci
; 54(4): 93-9, 2005 Dec.
Article
em En
| MEDLINE
| ID: mdl-16398053
ABSTRACT
The aim of this study was to determine the effects of vasopressin V1 receptor antagonism on regional hemodynamics in spontaneously hypertensive rats (SHR/Izm). Changes in blood flow in the superior mesenteric artery or terminal aorta were measured in rats with a chronically implanted electromagnetic flowmeter. The combination of a non-hypotensive hemorrhage (0.3 ml/100 g weight) and ganglionic blockade with hexamethonium bromide (C6; 25 mg/kg weight) had no effect on mesenteric resistance. On the other hand, subsequent intravenous administration of a peptide vasopressin V1 receptor antagonist (V1A; 10 microg/kg[d(CH2)5(1)-O Methyl-Tyr(2)-Arg8]-vasopressin) significantly reduced mesenteric resistance in SHR/Izm but had no effect on hindquarter resistance. Furthermore, the infusion of C6 (after pretreatment with hemorrhage plus V1A) induced a marked reduction of blood pressure and a significant decrease in superior mesenteric resistance only in SHR/Izm. Thus, we showed an altered reactivity to V1A in the superior mesenteric and/or hindquarter vascular regions of SHR/Izm, suggesting that maintenance of elevated resistance in the mesenteric vascular bed mainly relates to a potential vasopressin-mediated vasoconstriction and that a new sympathetic vasoconstrictor tone is generated within the superior mesenteric vascular bed to compensate for hypotensive intervention (minor hemorrhage plus V1A) in conscious SHR/Izm.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Simpatolíticos
/
Receptores de Vasopressinas
/
Antagonistas dos Receptores de Hormônios Antidiuréticos
/
Hemorragia
Limite:
Animals
Idioma:
En
Revista:
Hiroshima J Med Sci
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Japão