PERTUSSIS-TOXIN-SENSITIVE G-PROTEINS IN REGENERATED ENDOTHELIAL-CELLSOF PORCINE CORONARY-ARTERY

Endothelium-dependent, pertussis toxin-sensitive relaxations are impai red selectively after regeneration of endothelial cells following ball oon denudation of the porcine coronary artery. The present study was d esigned to examine the hypothesis that there is a difference in G prot eins modified by pertussis toxin between regenerated and intact endoth elial cells. Yorkshire pigs, fed a high-cholesterol diet, underwent ba lloon denudation of the endothelium of the left anterior descending co ronary arteries (LAD). Four weeks after the denudation the animals wer e killed to detect G proteins by ADP ribosylation catalyzed with pertu ssis toxin and [P-32]NAD, separated on a urea gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In membrane fractions of e ndothelial cells obtained from previously denuded LAD, G alpha(i-1)/G alpha(i-3) (41 kDa) and G alpha(i-2) (40 kDa) proteins were labeled. T he two bands revealed on the gel were the same as those obtained from intact left circumflex coronary arteries (LCX). However, the intensity of the bands was less prominent in the LAD than the LCX. These result s suggest that either a decreased amount or a reduced functionality of G(i) proteins in the regenerated endothelial cells may account for th e impairment in the pertussis toxin-sensitive relaxations after balloo n injury of coronary arteries in the pigs.