Effects of trapidil on ATPase, lipid peroxidation, and correlation with ultrastructure in experimental spinal cord injury

The present study was performed to investigate the effect of trapidil on ischemic damage of cells after spinal cord injury. The injury was produced by extradural clip compression of the exposed spinal cord in rats according to Rivlin and Tator. The ten rats in group 1 were used to determine normal findings without any surgery or medication. On the 15 rats in group 2, only six-level laminectomy was performed to determine the influence of the total laminectomy on the biochemical factors measured and the, light and ultrastructural findings. The 15 rats each in groups 3 and 4 were used as trauma and trapidil (40 mg/kg) treatment groups, respectively. The injury actually produced a significant decrease in Na+-K+/Mg+2 ATPase activity of the injured segments as early as 10 min after trauma. Trapidil attenuated Na+-K+/Mg+2 ATPase inactivation in the traumatized rats for 120 min after treatment (P<0.05) and significantly reduced the malone dialdehyde content below that in the traumatized group at all determined times (P<0.05). Light and electron microscopic findings supported the biochemical results.

Paracrine effect of human vascular endothelial cells on human vascular smooth muscle cell proliferation: transmembrane co-culture method

To investigate the role endothelial cells have on underlying smooth muscle cell proliferation, human aortic vascular smooth muscle cells were co-cultured with human aortic endothelial cells at different cell densities, using a transmembrane co-culture method. Subconfluent endothelial cells subseeded at low (0.5 x 10(4) cells/well) and medium densities (2.0 x 10(4) cells/well) stimulated smooth muscle cell proliferation by 43 +/- 14% (P < 0.01) and 39 +/- 8% (P < 0.02), respectively. However, this stimulatory effect on smooth muscle cell proliferation was not evident in confluent endothelial cells subseeded at high cell density (8.0 x 10(4) cells/well). Treatment of smooth muscle cells with trapidil, at 10(-6) M, for anti-platelet derived growth factor (PDGF) effect or with endothelin-1 receptor blocker FR 139317, at 10(-6) M failed to inhibit this stimulatory effect. These results imply that subconfluent human endothelial cells are able to exert a stimulatory effect on human smooth muscle cell proliferation, and that this endothelial paracrine growth effect may not be mediated by endothelin or PDGF.

[Biotransformation of the trapidil (rocornal) derivative AR 12463 in the rat]

After p.o. administration of 5-piperidino-7-[N-pentyl-N-(beta- hydroxyethyl)]amino-s-triazolo[1,5-a]pyrimidine (1; AR 12463) more than 15 metabolites were isolated from urine and feces of male Wistar rats. Only small amounts of unchanged 1 were observed. The structure of 12 metabolites was elucidated or proposed on the basis of UV-, 13C NMR- and mass spectra. Main metabolites are 5-piperidin-4'-olyl-7-[N-pentyl-N-(beta- hydroxyethyl)]amino-s-triazolo[1,5-a]pyrimidine and 5-piperidin-4'-olyl-7-[N-pent-4-olyl-N-(beta-hydroxyet hyl)]amino-s- triazolo[1,5-a]pyrimidine. The other metabolites are mainly hydroxy- or ketopentyl derivatives and piperidinoles or piperidinones, respectively. Conjugates of most of the metabolites were identified, but the ratio phase-I/II metabolites was about 3:1. In contrast to trapidil, 5-methyl-7-diethylamino-s- triazolo[1,5-a]pyrimidine, no hydroxy derivatives of the bicyclic system were observed. The major part of unchanged 1 and metabolites is excreted via kidneys.

[The bioavailability of trapidil from suppositories (author's transl)]

In a study with five healthy persons designed to compare the bioavailability of Trapidil from Rosupol U suppositories with that from Witepsol H 15 suppositories, the availability of Trapidil from the Rosupol U suppositories was inferior in four of the five test subjects. The difference in the amounts of released drug observed in vivo was smaller than that found in vitro.

[HPLC of trapidil (Rocornal) and metabolites (author's transl)]

Trapidil (1; Rocornal) and 10 metabolites can be separated by a gradient technique on reversed phases (RP-8 instant columns) using the eluents methanol/water and acetonitrile/phosphate buffer (pH = 5.4); ultraviolet detection. Furthermore, HPLC techniques for purity testing and for determining 1 in serum are described.