Inhibition of serum diamine oxidase discloses a constitutive putrescine release from cultured vascular smooth muscle cells

OBJECTIVE: To determine if putrescine and the higher polyamines spermidine and spermine are released from cultured vascular smooth muscle cells.MATERIAL: Vascular smooth muscle cell line A7r5.TREATMENT: Cells were treated with aminoguanidine (10 or 100 microM) for 1 to 24 h with or without fetal calf serum (10%) present in the culture medium.METHODS: Cellular and medium concentrations of polyamines were determined by liquid chromatography. Total cellular protein was determined by the Bradford procedure. Student's two-tailed t-test was used for statistical calculations.RESULTS: A constitutive release of putrescine was disclosed within 5 h if serum diamine oxidase was inhibited by 10 microM aminoguanidine. The release was linear with time for 24 h and specific for putrescine in the sense that the higher polyamines spermidine and spermine, despite similar cellular concentrations, were not released. Similar amounts of putrescine were released from the smooth muscle cells whether or not culture medium contained serum. Cells, that had been cultured in medium from which fetal calf serum had been omitted for last 48 h, contained less putrescine, spermidine and protein than those that persisted in medium that contained serum.CONCLUSION: A constitutive putrescine release from vascular smooth muscle cells is disclosed in the presence of aminoguanidine