| Part 1EFFECTS OF PRESSURE DISTENTION ONFUNCTION AND POST-GRAFTING STENOSIS OFRABBITS EXTERNAL JUGULAR VEINObjective To study the effects of different distention pressures on function of contraction/ relaxation of rabbits' external jugular vein and on the formation of post-grafting stenosis, and explore its possible mechanism.Methods Forty—five New Zealand rabbits were randomly divided into three groups: group A, group B and group C, 15 rabbits in eachgroup. The external jugular veins were distended under pressure of 20mmHg (group A), 80mmHg (groupB) and 150mmHg (groupC) respectively. Part of vein in each group were cut off and suspended for isometric tension recording. Contraction/relaxation to NA and Papaverine were observed, and the expression of C-fos and C-myc genes were measured by RT-PCR. The vein segments were grafted into common carotid artery with cuff technique, grafting veins were sampled after 4 weeks, and the intimal thickness , the ratio of thickness of intima/media and expression of C-fos and C-myc genes were examined. Results1. The contraction to NA: the — logED50 in group C (4.84±1.21) was significantly lower than that in group A (5.78±0.86) (P<0.05) and group B (5.76±0.95) ( P< 0.05) ; the maximum contractility in group C (10.12± 1.98) g was significantly lower than that in group A (13.62±1.68) g (P<0.01)and group B (12.98±1.89) g (P<0.01) .2. The relaxation to narceine: the — logED50 in group A (6.75±0.82) was significantly higher than that in group B (5.86±0.68) ( P<0.01), and the — logED50 in group B was significantly higher than that in group C (5.14±0.76) ( P< 0.05 ) ; the maximum relaxation in group A (70.28±4.55)% was significantly higher than that in group B (62.78±8.92)% ( P< 0.01 ) , and the maximum contractility in group B was significantly higher than that in group C (50.89±6.69)% (P< 0.01) .3. The gene expression of isolated veins: Before graft, C-fos and C-myc genes cannot be detected in veins in all the groups.4. The instent of stenosis of grafted veins: The intima thickness in group C (53.24±8.21) um was significantly higher than that in groupA (45.88±7.66) urn (P<0.05) and group B (46.29±9.15) \xm (P< 0.05 ) , There were no significant differences between group A and B; The ratio of intima/media in group C (2.12±0.38) was significantly higher than that in group A (1.82±0.38) (P<0.05) and group B (1.78±0.29) (P<0.05) . There were no significant differences between group A and B.5. The gene expression of grafted veins: 4 weeks later, the relative coefficients of C-fos and C-myc genes in group C (0.88±0.11)/ (0.92±0.09) were significantly higher than group A (0.64±0.08)/ (0.79±0.06) and group B (0.68±0.07) / (0.81±0.07) (P<0.01) .There were no significant differences between group A and B. Conclusions1. Low distention pressure can better preserve the function of contraction/relaxation of blood vessel.2. Low distention pressure can alleviate the intima proliferation of grafted vein vessel.3. Different distention pressures can influence the expression of C-fos and C-myc genes in grafted vein vessel.4. Distention pressure maybe directly or indirectly promote the pression of C-fos and C-myc genes, which affects the intima proliferation.Part 2THE EFFECT OFANTISENEOLIGODXYNUCLEOTIDES OF C-FOSAND C-MYC GENES ON RABBITS VENOUSPOST-GRAFTING STENOSISObjective To explore the effects of C-fos and C-myc antisense oligodxynucleotides (ASODN) on the rabbits venous post-grafting stenosis.Methods Sixty New Zealand rabbits are randomly divided into four groups: control group^ experimental group A>B and C. Part of jugular veins were cut off and disposed with lipofectin only in control group, transfected with ASODN targeting C-fos and C-myc genes in experimental group A> B and combined the two ASODNs in group C respectively, then the segments of jugular vein were transplanted into common carotid artery in the same side. The grafted veins were taken off after 4 weeks. The changes of mRNA of C-fos and C-myc and the expression of C-fos, C-myc and PCNA proteins were measured by RT PCR and immunohistochemistry; and the intimal thickness ^ the ratio of thickness of intima/media were examined. Results1. The genes expression of grafted veins: Compared with control group, the expression of mRNA of C-fos gene was decreased significantly (P<0.01) in the three experimental groups with the relative coefficients (0.67±0.11)> ( 0.47±0.09 ) ^ ( 0.58±0.08 ) >( 0.46±0.07) respectively; the expression in group A was lower than that in group B ( P<0.01) ; the expression of mRNA of C-myc gene was decreased significantlyC P<0.01 )in the three experimental groups with the relative coefficients (0.82±0.12), (0.71±0.13), (0.57±0.11K( 0.54±0.08) respectively; the expression in group A was higher than that in group B ( P<0.01) .2. The proteins expression of grafted veins: The expression of C-fos^ C-myc and PCNA proteins were positive in all the four groups. LI of PCNA protein was (61.23±8.64) %, (45.81±5.33) %, (47.12±7.02) %> ( 35.54±6.21 ) % respectively, group A,B,C were lower than that in control group(P< 0.01), and group C was lower that in group A,B(P < 0.01).3. The instent of stenosis of grafted veins: After 4 weeks, the thickness of intima of veins were (46.01±8.44) p, (40.28±5.68) |im, (39.97±4.77) p, (33.24±4.21) urn respectively in the four groups with group A^ B> C lower than that in control group (P<0.01) and group C lower than that in group A, B (P<0.01). The ratio of intima/media were (1.71 ±0.29^ (1.48±0.3 3), (1.47±0.37), (1.12±0.19) respectively with group A, B ,C lower than that in control group ( P <0.05, P<0.01) and group C lower than that in group A,B (P<0.01) . Conclusions1. The ASODNs of C-fos and C-myc can inhibit the expression of C-fos and C-myc genes, and can alleviate stenosis of grafted vein vessel.2. Combining C-fos and C-myc ASODNs can prevent stenosis of grafted veins better.3. C-fos and C-myc maybe promote each other and co-ordinate in the process of stenosis.
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