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Longitudinal analysis of AT‐1 angiotensin receptor binding in the rostral and caudal ventrolateral medulla and nucleus of the solitary tract in the rat brainstem
Author(s) -
Bourassa Erick A.,
Speth Robert C.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1169.13
Subject(s) - rostral ventrolateral medulla , solitary tract , medulla , brainstem , medulla oblongata , endocrinology , medicine , chemistry , angiotensin ii , nucleus , solitary nucleus , central nervous system , anatomy , biology , blood pressure , neuroscience
The solitary tract nucleus (NTS), caudal ventrolateral medulla (CVLM) and rostral ventrolateral medulla (RVLM) are brainstem structures that have been identified as central sites at which blood pressure is controlled. Each are reported to be responsive to angiotensin II (Ang II) and to contain type 1 Ang II receptors (AT1R). This study used quantitative densitometric saturation autoradiography to determine the density of AT1R in the RVLM and CVLM of the female rat. Results showed that specific binding of 125I‐Sarcosine1, Isoleucine8 Ang II in the NTS had high density (1207 ± 99.8 fmol/g wet weight) and high affinity (KD of 328 ± 12.3 pM). Specific binding was much lower in the CVLM and RVLM. The CVLM (−14.24 to −13.76 mm relative to Bregma) contained 379 ± 63.9 fmol/g wet weight. The KD (178 ± 27.2 pM) was significantly lower than NTS (p<0.01). The density of AT1R in the RVLM (−13.64 to −12.08 mm relative to Bregma) was 275 ± 38.1 fmol/g wet weight with KD=164 ± 20.4 pM (p<0.01 versus NTS). These results indicate that there is a low density, but high affinity population of AT1Rs in the CVLM and RVLM that are the likely mediators of the effects of locally acting and exogenously applied Ang II on blood pressure in rats. This study was supported by the Peptide Radioiodination Service Center, University of Mississippi.