1. In basal conditions, plasma arterial prostaglandin (PG) E2 was significantly increased in borderline hypertensive patients (BH) (28.5 ± 6.7 pg/ml) in comparison with sustained essential hypertensive patients (EH) (11.6 ± 3.2 pg/ml) and in comparison with control normotensive subjects (NTS) (5.8 ± 1.4 pg/ml).
2. Plasma arterial PGE2 was positively significantly correlated with cardiac index and negatively significantly correlated with total peripheral resistance in basal conditions.
3. Indomethacin induced more pronounced haemodynamic changes in borderline than in sustained hypertensive patients, with a significant increase in arterial blood pressure and total peripheral resistance and a significant decrease in stroke volume and cardiac index.
4. Indomethacin significantly decreased arterial PGE2 in borderline hypertensive patients. The decrease was less important in sustained hypertensive patients.
5. In the overall population, a significant positive correlation between arterial PGE2 concentration and cardiac index was observed before and after indomethacin treatment.
6. The study suggests an important role of PGE2 in the regulation of cardiac output (positive inotropic effect) and blood pressure of essential hypertensive patients.