Testing in hypertension

Mendlowitz, Milton; Naftchi, Nosrat E.; Gitlow, Stanley E.; Wolf, Robert L.

doi:10.1016/0002-8703(68)90206-8

Cited by 4 publications

(1 citation statement)

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“…A discrepancy between the excretion of endogenous normetanephrine and the levels of 3 H-normetanephrine found in the urine after intravenous injection of 3 H-NE may exist not only in DOCA-salt hypertension but under selected conditions also in human hypertension (22,23). The difficulty with studying the fate of 3 H-NE in this fashion is that its tissue distribution will be proportional to blood flow (24) so that a more rapid disappearance of 3 H-NE from plasma may be due in large part to clearance and destruction in kidney and liver as well as uptake in organs such as heart (24).…”

Section: Discussionmentioning

confidence: 99%

Catecholamine Metabolism in Hypertensive Rats

Louis

Krauss

Kopin

et al. 1970

Circulation Research

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The possible role of catecholamines in two forms of experimental hypertension in rats was investigated further. Inbred, spontaneously hypertensive (SH) Wistar rats had unchanged endogenous levels of norepinephrine (NE) in the three tissues studied, and a significantly (P<0.05) decreased rate of NE synthesis ( 14 C-tyrosine technique) in heart and brainstem but not in gut, in comparison to normotensive Wistar rats. Also, the levels of free fatty acids (FFA) and major urinary catecholamine metabolites in plasma revealed no evidence of increased catecholamine turnover or release. Sprague-Davvley rats rendered hypertensive by treatment with desoxycorticosterone acetate and 1% salt had decreased cardiac NE concentration and increased cardiac NE turnover (•''H-NE technique) and cardiomegaly, confirming the work of others. However, urinary normetanephrine and plasma FFA did not differ from those in normal rats. These and other results fail to support but do not completely exclude a primary role for catecholamines in either type of hypertension. MethodsExperiments were carried out on male SH rats and normotensive rats weighing 140 to 200 g and aged 11 to 14 weeks (8). Each hypertensive rat was carefully matched for age and weight with a normotensive control rat. Systolic blood pressure was measured weekly and on the day before each experiment in the unanesthetized state using a tail plethysmographic technique (9). The question of a suitable control for a genetic strain of rats is of fundamental importance (8). We use normotensive Wistar rats of the same strain, bred brother to sister and housed in the same animal house under the same conditions as the hypertensive rats. Both groups of rats are then treated identically, have similar growth rates, and accept skin grafts.In studies on the synthesis of NE from radioactive tyrosine, rats were given 0.5 ml 0.9% NaCl solution containing 20 fie of L-tyrosine-14 C (u.l., New England Nuclear Corporation, 370 mc/mmole) into a tail vein and were killed by decapitation at various times after injection. Blood samples were collected in heparin and centrifuged, and aliquots of plasma were analyzed for endogenous and labeled tyrosine. The heart, brainstem, and proximal ileum were removed rapidly, cooled on dry ice, homogenized in cold 0.4N perchloric acid, centrifuged, and analyzed for 14 C-labeled and endogenous NE.

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Section: Discussionmentioning

confidence: 99%