Amino acids modulate the hypotensive effect of angiotensin-(1-7) at the caudal ventrolateral medulla in rats.
The present experiment was designed to investigate the possible involvement of glutamate and taurine in the depressor response produced by angiotensin (Ang)-(1-7) at the caudal ventrolateral medulla (CVLM) in rats anesthetized with urethane and alpha-chloralose. Microinjection of Ang-(1-7) into the CVLM elicited a depressor response which was partially blocked by nonselective glutamate receptors antagonist kynurenic acid, whereas selective Ang-(1-7) antagonist Ang779 produced a pressor response which was significantly attenuated by taurine receptors antagonist 6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide. Release of glutamate and taurine in the CVLM was evaluated with microdialysis, and the contents of these amino acids were measured with high performance liquid chromatography-fluorescent detection. The depressor response to Ang-(1-7) was accompanied by an increased release of glutamate and a decrease of taurine at the CVLM, whereas the pressor response to Ang779 was associated with a decreased release of glutamate and an increase of taurine. These results suggest that Ang-(1-7) and its antagonist Ang779 modulate the release of glutamate and taurine at the CVLM, which in turn contributes at least in part to the blood pressure response to Ang-(1-7) and Ang779.
Wang
Jin
J
Department of Physiology and Pathophysiology, Shanghai Medical College of Fudan University (The former Shanghai Medical University), Shanghai 200032, China.
Peng
Ying-Jie
YJ
Zhu
Da-Nian
DN
D000803:Angiotensin I / Q000008:administration & dosage*; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects*; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage; D018698:Glutamic Acid / Q000378:metabolism; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism*; D008845:Microinjections; D010446:Peptide Fragments / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000378:metabolism; D013654:Taurine / Q000378:metabolism
D000959:Antihypertensive Agents; D018691:Excitatory Amino Acid Antagonists; D010446:Peptide Fragments; D017470:Receptors, Glutamate; D013654:Taurine; D018698:Glutamic Acid; D000803:Angiotensin I; C118790:angiotensin I (1-7)