Hypertension Research Today is a free monthly online journal that collates and summarizes the latest research about Hypertension, including details on symptoms, diagnosis, diet, treatment, causes. | ||||||||
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Do incremental increases in blood pressure elicit neointimal plaques through endothelial injury?Ruiz-Feria CA, Yang Y, Nishimura H Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis TN 38163, USA. Fowl (males more than females) show maturation-dependent rises in blood pressure (BP) and formation of neointimal plaques (NPs), resembling balloon catheter injury-induced neointima, in the abdominal aorta (AbA) just above the bifurcation. The plaque comprises neointimal cells containing abundant endoplasmic reticulum and extracellular matrix. Hence, we investigated whether rapid incremental BP increases in male chicks trigger NP formation, possibly via endothelial injury in hemodynamically selective areas. In 6-wk-old chicks (n = 8) treated 4 wk with solvent (Sv; minipump) or arginine supplement (Arg; 0.3% in drinking water), BP increased from 140 +/- 5 to 159 +/- 4 (Sv) and from 138 +/- 4 to 157 +/- 3 (Arg) mmHg, whereas propranolol treatment (Prop, 8 mg.kg(-1).day(-1); minipump) prevented the rise. Arg and Prop groups had, respectively, 73% and 77% smaller (P < 0.05) NP areas and 19% and 25% less (P < 0.01) AbA medial thickness than Sv controls. In 16-wk-old cockerels, established BP remained high after Sv and Arg treatments. In the Prop group, BP decreased, but neither NP area nor medial thickness was lower than in the Sv group, whereas the Arg group showed greater NP area and medial thickness. Pulse pressure, determined by intravascular transducer, increased as the pulse wave descended the aorta. The results suggest that maturation-dependent rises in BP in chicks may trigger NP formation in the lower segment of the AbA, which was prevented by inhibition of BP increase, or via a possible increase in nitric oxide availability. BP reduction exerts no effect once BP reaches a plateau. Involvement of endothelial injury leading to NP formation and hemodynamic forces selective for the lesion-prone area remain to be determined. Published 5 November 2004 in Am J Physiol Regul Integr Comp Physiol, 287(6): R1486-93.
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