Endothelin does not contribute to the vasospasm after balloon angioplasty in vitro

The present study was undertaken in 43 rabbits to determine whether endothelin or potassium are mediating substances for vasospasm originating from the vessel wall after balloon angioplasty. Thirteen aortic segments were dilated and the luminal surfaces perfused. These perfusates were investigated for their vasomotor action per se and analyzed for their concentrations of potassium and endothelin-like immunoreactivity (ET-LI). The perfusates from angioplasty segments caused a contraction of 2.4 +/- 0.8 mN, while the perfusates from control segments only resulted in a contraction of 0.4 +/- 0.2 mN, (P = 0.004). There was no difference in the concentrations of potassium or ET-LI in the perfusates. Thirty aortic segments were used to measure the concentration of ET-LI in extractions of untreated, control, and angioplasty specimens. There was no statistically significant difference between the groups. Scanning electron microscopy demonstrated the angioplasty segments to be denuded of their endothelium. In conclusion, perfusates from rabbit aortic segments treated by angioplasty in vitro have a strong vasoconstricting effect, for which neither endothelin nor potassium seems to be responsible.