Prostaglandin I2 reduces activation of human arterial smooth muscle cells in-vivo.

Patients suffering from peripheral vascular disease have been "ultima ratio"-treated with PGI2 at a rate of 5 ng/kg/min for 6 hours a day and 5 consecutive days i.v. 20 of them underwent surgery thereafter as therapy was not sufficient. A histological examination and quantification of vascular tissue revealed that the number of activated smooth muscle cells was significantly lower in treated patients vascular segments than in untreated ones in all the different age groups. A comparable suppression was found in the intima and the media as well. It is thus concluded, that PGI2 inhibits smooth muscle cell proliferation most probably by inhibiting PDGF-release from the platelets and stimulation of smooth muscle cell cAMP. To achieve a more beneficial PGI2-effect at the vascular level, a prolonged PGI2-therapy looks rather promising.