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DIMINISHED SYMPATHETIC ACTIVITY IN TRANSGENIC RATS WITH LOW BRAIN ANGIOTENSINOGEN
Author(s) -
da Silva Ana Quenia Gomes,
CampagnoleSantos Maria J,
Santos Robson A S,
Baltatu Ovidiu,
Bader Michael,
Fontes Marco A P
Publication year - 2006
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.20.4.a755-b
Subject(s) - transgene , medicine , endocrinology , genetically modified mouse , sympathetic activity , chemistry , neuroscience , biology , gene , biochemistry , blood pressure , heart rate
The brain renin angiotensin system (RAS) is known to modulate the sympathetic output to the cardiovascular system by reacting with specific areas in the central nervous system. Recently, a transgenic rat model with low brain angiotensinogen levels TGR(ASrAOGEN) has been developed. In order to further confirm the involvement of brain RAS in the maintenance of sympathetic tonus and blood pressure, we tested the cardiovascular and sympathetic reactivity in presence of ganglionic blocker in this rat model. TGR(ASrAOGEN) (n=5) and Sprague‐Dawley rats (SD; n=6) were anesthetized (Urethane (1.2 g/Kg, IP) and prepared for cardiovascular parameters and renal sympathetic nerve activity (RSNA) recording. Intravenous injections of hexamethonium (2.5 mg/Kg, IV) in SD control rats caused a pronounced decrease in mean arterial pressure (−49±4 mmHg), heart rate (−42±6 bpm) and RSNA (−74±3 %). Strikingly, when compared with SD rats, intravenous injection of hexamethonium in TGR(ASrAOGEN) caused an attenuated fall in baseline mean arterial pressure (−27±6 mmHg; P <0.01) and heart rate (−17±5 bpm; P <0.05). Particularly, the fall in baseline RSNA was also greatly attenuated in TGR(ASrAOGEN) (−42±10 %; P <0.01). Our findings indicate that the TGR(ASrAOGEN) present a reduced vasomotor, cardiac and renal sympathetic tonus, implicating central angiotensin peptides in the maintenance of the sympathetic output. Financial Support: CNPq, Pronex and Fapemig.