OBJECTIVETo compare the action mechanisms of human and porcine derived erythrocyte-derived depressing factor (h-EDDF and p-EDDF) as well as the effects on blood pressure.

METHODSThe experiments were carried out in spontaneously hypertensive rats (SHR, n = 5) and two kidney-one click renal hypertensive rats (2K-1C, n = 7). The acute and chronic effects of h-EDDF and p-EDDF on blood pressure were observed, blood pressure test using tail plethysmography under unanaesthetic state. Both EDDF were administrated via jugular vein and/or oral respectively. The isolated thoracic aorta ring perfusion assay was used to examine the effect of EDDF on the asodilation. Primary cultured VSMCs were prepared from the thoracic aorta media of 2K-1C and normal Wistar rats. The effect of EDDF on proliferation of VSMCs were determined by MTT assay. The cell cycle of VSMCs was evaluated by flow cytometric.

RESULTSBoth h-EDDF and p-EDDF could significantly decrease blood pressure of Wistar rats through intravenous administration and/or orally (P < 0.01 and P < 0.05 respectively). The contractile response of aorta in 2K-1C rats to PE was significantly enhanced compared with that of the control (P < 0.01) and both EDDF (10(-3) g/ml) remarkably induced a vasodilation with endothelium-dependent manner in SHR and 2K-1C rats (P < 0.05). h-EDDF and p-EDDF could significantly inhibit the proliferation of VSMCs from 2K-1C and control rats. After 24 hours of exposure to EDDFs the cell number of G0/G1 phase obviously increased and cell number in S phase was decreased (P < 0.01, respectively).

CONCLUSIONSIt seems that the effects of h-EDDF and p-EDDF on blood pressure and vasodilation as well as inhibition of VSMCs proliferation and regulation of cell cycle have no significant difference.