AIM AND METHODSTo determine the relationship between the nuclear envelope nucleoside triphosphatase (EC 3. 6. 1. 15, NTPase) activity and the phenotypic modulation of vascular smooth muscle cell (VSMC), the NTPase activity was detected during restenosis after de-endothelialization in vascular wall. The activities of three enzymes involved in carbohydrate and nucleic acid metabolism were also investigated by spectrophotometry.

RESULTSThe activity of NTPase increased continuously and associated with the process of intimal thickening. Western blotting showed that expression of SMalpha-actin, as the marker of contractile phenotype of VSMC, decreased continuously. Osteopontin (OPN), the marker of synthetic phenotype of VSMC, was up-regulated during the process. These suggested that intimal injury induced phenotypic modulation of VSMC. The activities of 5'-nucleotidase, adenosine deaminase and succinate dehydrogenase increased and reached their peaks on 7 days after de-endothelialization. The changes of three enzymes were associated with proliferation in VSMC.

CONCLUSIONThe efflux of mRNA and the changes of enzyme activity involved in carbohydrate or nucleic acid metabolism may be the biochemical basis in the development and progression of restenosis.