PLASMA GROWTH-FACTOR ACTIVITY AND CARDIAC WALL THICKNESS

Objectives. The aim of this study was to investigate the growth factor activity in plasma (GFAP) in hypertension, and the correlation of GFA P to blood pressure levels, cardiac structural changes and platelet ac tivation at rest and during exercise. Subjects. Fifteen untreated hype rtensive subjects and 15 normotensive controls were recruited from a b lood pressure screening programme. Interventions. GFAP before and afte r 30 min of strenuous exercise was analysed as the ability of patient or control plasma to stimulate incorporation of H-3-thymidine in cultu red human smooth muscle cells. M-mode echocardiography was performed a nd platelet activity was measured by the excretion of the urinary meta bolite of thromboxane A2. Results. There were no significant differenc es in GFAP or platelet activation at rest or after exercise between th e groups. The fractions of labelled cells were 52.6% vs. 56.6% (HT vs. NT) at rest. Septum and posterior wall end-diastolic thicknesses (PWT [D]) were significantly increased in the HT group (10.4+/-0.3 vs. 9.2/-0.3 mm and 11.4+/-0.5 vs. 10.0+/-0.4 mm, respectively, P < 0.05). PW T(D) was significantly correlated to GFAP (r = 0.40, P = 0.04) and to blood pressure (r = 0.53, P < 0.005) but there was no correlation betw een blood pressure and GFAP. Conclusion. The data suggest that GFAP co uld play a role in the early development of cardiac hypertrophy in hyp ertension, but that this effect does not seem to be directly linked to blood pressure levels alone.