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 presser 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 roup (6.8+/-4.5 pg/ml; P<0.05). In conclusion, our study demonstrated that after 10 min of cold presser stimulus an increase of circulating ET-1 levels was seen in borderline hypertensives.