Fall in blood pressure produced from discrete regions of the ventral surface of the medulla by glycine and lesions

Abstract

SUMMARY1. In cats anaesthetized with pentobarbitone sodium, atropinized by i.v. atropine methyl nitrate and artificially ventilated, experiments were carried out (a) to localize the site where glycine acts on the ventral surface of the medulla when, on topical application through paired Perspex rings caudal to the trapezoid bodies, it produces a fall in arterial blood pressure, (b) to compare the effects of uni-and bilateral application, and (c) to study the blood pressure effects produced by electrolytic lesions of the glycinesensitive areas.2. Blood pressure fell only a little on unilateral application of glycine through one of the Perspex rings, but a pronounced fall occurred on its bilateral application. The fall was too large to be explained by two minimal responses added together. Thus the application of glycine to one side potentiated the depressor effect of glycine applied to the other side.3. By moving the paired Perspex rings rostrally or caudally to different positions on the medulla and determining for each position the effectiveness of glycine, the glycine-sensitive areas were found to be restricted to a 1.5 mm wide strip situated 1-2 5 mm caudal to the trapezoid bodies. By making electrolytic lesions within the limits of this strip the glycinesensitive areas were found to be not wider than 1-5 mm in the mediolateral direction and to be situated about 4 mm lateral to the mid line. Histologically, such lesions involved the cells of the parvicellular part of the lateral reticular nucleus. 4. Placing an electrode, with a diameter of 1 mm, under light pressure on the glycine-sensitive area produced a short-lasting steep rise in blood

Inhibition of Vasopressin Release to Carotid Occlusion by Γ‐aminobutyric Acid and Glycine

“…But applied to region A, they caused no such inhibition; in each of the five experiments the carotid occlusion carried out during this application produced strong release of vasopressin. (Guertzenstein, 1973;Guertzenstein & Silver, 1974). In the present experiments both amino acids were found not only to lower arterial blood pressure when applied to region A, but also greatly to attenuate the pressor response to carotid occlusion when applied in high concentrations (GABA 50 and 100 mg/ml; glycine 25 and 50 mg/ml).…”

Vasopressin Release by Nicotine: The Site of Action

“…Recently, it has been shown that a number of drugs which, on intraventricular injection affect blood pressure, heart rate, respiration or blood glucose, act in this way (Feldberg & Guertzenstein, 1972;Guertzenstein, 1973;Bousquet & Guertzenstein, 1973;Edery & Guertzenstein, 1974;Feldberg & Gupta, 1974;Guertzenstein & Silver, 1974;Dey, Feldberg & Wendlandt, 1975).…”

Brain Angiotensin-II-derived Reactive Oxygen Species: Implications for High Blood Pressure

“…The importance of the RVLM for maintaining blood pressure in anesthetized animals had first been documented 130 years ago [21]. However, only after the pioneer studies performed by Guertzenstein and colleagues [22] suggesting that supraspinal sympathetic vasomotor drive originates from the RVLM that truly brought researcher's attention to this brainstem area [22,23].…”