title: Role of the rostral ventrolateral medulla in maintenance of blood pressure in rats with Goldblatt hypertension.
abstract: The aim of the present study was to examine the participation of the rostral ventrolateral medulla (RVLM) in the maintenance of hypertension in rats submitted to the renovascular Goldblatt (two-kidney, one clip) procedure. We inhibited or stimulated this area with the use of drugs such as glycine, L-glutamate, or kynurenic acid. (1) Bilateral microinjection of glycine (100 nmol, 200 nL, n = 13) into the RVLM of hypertensive rats produced a decrease in mean arterial blood pressure (MAP) from 177.2 +/- 29.3 to 102.3 +/- 20.9 mm Hg (P < .05), which was similar to the decrease produced by intravenous administration of hexamethonium. The inhibition of RVLM with glycine in normotensive rats produced a decrease in MAP from 106 +/- 17.1 to 59.7 +/- 7.3 mm Hg (P < .05, n = 9). (2) An impressive increase in MAP from 153.3 +/- 16.3 to 228 +/- 34.9 mm Hg (P < .05) occurred in hypertensive rats after microinjection of L-glutamate (50 nmol, 200 nL, n = 6) into the RVLM. The same procedure caused a significant but less intense increase in MAP from 105 +/- 13.8 to 148.3 +/- 24.9 mm Hg in normotensive rats (P < .05, n = 6). (3) A decrease in MAP from 151.6 +/- 25.3 to 96.8 +/- 22.5 mm Hg occurred in hypertensive rats after microinjection of the broad-spectrum glutamate antagonist kynurenic acid (4 nmol, 200 nL, n = 6) into the RVLM, whereas the same procedure did not change MAP in normotensive animals (n = 6). Heart rate was not significantly affected in any group.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000008:administration & dosage / Q000494:pharmacology; D005998:Glycine / Q000008:administration & dosage / Q000494:pharmacology; D006339:Heart Rate; D018738:Hexamethonium / Q000494:pharmacology; D006978:Hypertension, Renovascular / Q000503:physiopathology*; D007736:Kynurenic Acid / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000503:physiopathology*; D008845:Microinjections; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000502:physiology
chemical_list: D000959:Antihypertensive Agents; D018691:Excitatory Amino Acid Antagonists; D017470:Receptors, Glutamate; D018738:Hexamethonium; D018698:Glutamic Acid; D007736:Kynurenic Acid; D005998:Glycine