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This Article Full Text Full Text (PDF) All Versions of this Article: 106/6/1943    most recent 90516.2008v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Shimizu, F. Articles by Takamata, A. PubMed PubMed Citation Articles by Shimizu, F. Articles by Takamata, A.

Involvement of central angiotensin II type 1 receptors in LPS-induced systemic vasopressin release and blood pressure regulation in rats

¹Department of Anesthesiology, Kyoto Prefectural University of Medicine, Kyoto; and ²Department of Environmental Health, Nara Women's University, Nara, Japan

Submitted 10 April 2008 ; accepted in final form 7 April 2009

The purpose of this study was to evaluate the involvement of central angiotensin II (ANG II) and ANG II type 1 (AT₁) receptors in systemic release of arginine vasopressin (AVP) and blood pressure regulation during endotoxemia. LPS (150 µg/kg) was injected intravenously 30 min after intracerebroventricular (icv) losartan (50 µg), an AT₁ receptor antagonist, or subcutaneous (sc) captopril (50 mg/kg), an angiotensin-converting enzyme inhibitor. Rats with icv and sc saline injections served as control. LPS administration increased plasma AVP concentration from 2.1 ± 0.2 to 15.2 ± 2.5 pg/ml (60 min after LPS injection) without significant changes in plasma osmolality or hematocrit. LPS-induced AVP secretion was significantly attenuated by pretreatment with icv losartan (2.3 ± 0.5 to 3.7 ± 0.5 pg/ml) but was not attenuated after peripheral captopril treatment (2.2 ± 0.6 to 17.6 ± 4.2 pg/ml). LPS administration significantly decreased systolic blood pressure (SBP) by 22.7 ± 5.4 mmHg after intravenous LPS injection in icv losartan-treated rats, while SBP remained unchanged in vehicle-treated or sc captopril-treated rats by intravenous LPS. These results indicate that central AT₁ receptors, not responsive to peripheral ANG II, play an important role in systemic AVP secretion and maintenance of blood pressure during endotoxemia.

endotoxemia; lipopolysaccharide; losartan; arginine vasopressin; captopril