Plasma endothelin concentration: Relation with vascular resistance and comparison before and after balloon dilatation procedures

Endothelin (ET) is a potent vasoconstrictor peptide with an as yet uncertain physiological role in cardiovascular disease. We measured blood plasma ET concentrations using a recently developed radioimmunoassay and analysed the relations between ET concentration, systemic arterial pressure and systemic vascular resistance. In addition, ET levels before and after percutaneous balloon valvuloplasty and angioplasty were measured. Fifty-one patients were studied: (1) 13 patients with small left-to-right shunting or Kawasaki heart disease (age ranged from 4 to 144 months); (2) 10 patients who had undergone ballon valvuloplasty or angioplasty (age ranged from 1 to 233 months) and (3) 28 healthy infants and children (age ranged from 3 to 152 months). Systemic vascular resistance was calculated by the formula (mean aortic pressure — mean right atrial pressure) X 80/cardiac output (dyne·sec·cm−5). Plasma ET concentrations in healthy children less than 2 years were significantly higher than those over 2 years (2.48±0.62 vs 1.31±0.53 pg/ml). In eight patients in groups 1 and 2, plasma ET concentration in the pulmonary artery (2.00±0.43 pg/ml) was significantly lower than that in the femoral vein (2.39±0.69 pg/ml) and aorta (2.23±0.59 pg/ml), suggesting ET secretion derived from endothelial cells in peripheral pulmonary vessels. There was a significant positive correlation between ET concentrations in the femoral vein and systemic vascular resistance (r=0.55,p<0.05). After balloon dilatation ET concentration rose from 2.15±0.82pg/ml to 2.61±1.38 pg/ml. These results suggest that ET may be a stress-induced hormone which is secreted by the transient hypotension following percutaneous balloon dilatation and which regulates peripheral vascular tonus.