Role of the rostral ventrolateral medulla in maintenance of blood pressure in rats with Goldblatt hypertension

• Published in: Hypertension (Dallas, Tex. 1979) Vol. 26; no. 6; pp. 1117 - 1120
• Main Authors: BERGAMASCHI, C, CAMPOS, R. R, SCHOR, N, LOPES, O. U
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Philadelphia, PA Lippincott 01.12.1995; Hagerstown, MD American Heart Association, Inc
• Subjects: Animals; Antihypertensive Agents - pharmacology; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Blood Pressure - drug effects; Blood Pressure - physiology; Cardiology. Vascular system; Excitatory Amino Acid Antagonists - pharmacology; Experimental diseases; Glutamic Acid - administration & dosage; Glutamic Acid - pharmacology; Glycine - administration & dosage; Glycine - pharmacology; Heart Rate; Hexamethonium - pharmacology; Hypertension, Renovascular - physiopathology; Kynurenic Acid - administration & dosage; Kynurenic Acid - pharmacology; Male; Medical sciences; Medulla Oblongata - drug effects; Medulla Oblongata - physiopathology; Microinjections; Rats; Rats, Wistar; Receptors, Glutamate - physiology
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/01.hyp.26.6.1117

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.