Plasma growth factor activity and cardiac wall thickness

The aim of this study was to investigate the growth factor activity in plasma (GFAP) in hypertension, and the correlation of GFAP to blood pressure levels, cardiac structural changes and platelet activation at rest and during exercise.

Fifteen untreated hypertensive subjects and 15 normotensive controls were recruited from a blood pressure screening programme.

GFAP before and after 30 min of strenuous exercise was analysed as the ability of patient or control plasma to stimulate incorporation of 3H-thymidine in cultured human smooth muscle cells. M-mode echocardiography was performed and platelet activity was measured by the excretion of the urinary metabolite of thromboxane A2.

There were no significant differences in GFAP or platelet activation at rest or after exercise between the 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). PWT(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 between blood pressure and GFAP.

The data suggest that GFAP could play a role in the early development of cardiac hypertrophy in hypertension, but that this effect does not seem to be directly linked to blood pressure levels alone.