Plasma endothelin-1 levels in normotensive and borderline hypertensive subjects during a standard cold pressor test.

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide derived from endothelium. The presence of ET-1 in human vascular endothelium and in the plasma suggests that it may play a role in the regulation of vascular tone and blood pressure (BP) in humans. The aim of this study was to evaluate the behaviour of plasma ET-1 in 10 normotensives (average 36.3 +/- 14.8 years) and 10 borderline hypertensives (average 42.0 +/- 11.7 years) before, during and after a standard cold pressor test. We also evaluated the behaviour of heart rate and BP at the same time. Our results demonstrated that the baseline (-10 and 0 min) plasma ET-1 values were identical for the two groups (8.6 +/- 5.8 and 8 +/- 4.7 pg/ml in normotensives; 7.8 +/- 2.7 and 7 +/- 2.4 pg/ml in borderline hypertensives). A statistically significant increment was verified 10 min after exposure to cold in the borderline hypertensive group (12.1 +/- 5.1 pg/ml) compared with the normotensives group (6.8 +/- 4.5 pg/ml; P < 0.05). In conclusion, our study demonstrated that after 10 min of cold pressor stimulus an increase of circulating ET-1 levels was seen in borderline hypertensives.