- Email: [email protected]
3.4 Retinoic acid suppresses intimal hyperplasia and prevents vessel remodeling following arterial injury in the rat
23rd
World Congress of the ISCVS
3.3 Analysis of Microcirculatory Changes After Femorodistal Arterial Reconstructions G. KERESZTURY, S. SCHULTE and S. HORSCH, Cologne, Germany The aim of our prospective study was to register microcirculatory changes of the foot after femorodistal arterial reconstructions. Thirteen patients were included with P.A.O.D. grade II-IV, who were treated with primary femorodistal bypasses between 1 June 1996 and 1 October 1996. We performed the following measurements 1 week before and after surgery. (1) Transcutaneuos oxygen tension (TcP02) on the dorsum of the foot and thoracic wall and calculation of gradient (ATcPO,); (2) Laser Doppler floxmetry on the dorsum of the toe (L-Flux); (3) Vital capillary microscopy-videodensitometry of the toe (cap. dens.); (4) Vital capillary microscopy-red blood cell velocity (RFV) of the toe. Results:
ATcP02
L-Flux
Before After
35.4 13.7
18.1 20.8
cap. dens.
RFV
15.2 16.9
0.23 0.17
(1) The oxygen tension in the nutritive and shunt capillaries increased significantly; (2) There is a light increase of the circulation in the nutritive and shunt capillaries measured by L-Flux; (3) The density of the nutritive capillaries did not change after 1 week postoperatively; (4) The blood flow velocity in the nutritive capillaries remained unchanged. Our results show, that in the first 6 days after successful femorodistal bypasses there is a circulatory improvement in the shunt capillaries without any improvement in the nutritive capillaries.
3.4 Retinoic Acid Suppresses Intimal Hyperplasia and Prevents Vessel Remodeling Following Arterial Injury in the Rat ].R UMANA, I.D. DeROSE, ]R, 1.0. MADIGAN, J.H. PRYSTOWSKY, WS. BLANER, D. STERN, R. NOWYGROD, M.C.OZ and G.]. TODD, New York, New York, USA Retinoids are derivatives of vitamin A capable of binding to nuclear receptors and mediating the transcription of over 150 genes involved in cellular differentiation and proliferation. Retinoic acid receptors have been demonstrated in smooth muscle cells (SMC) which can bind retinoids and inhibit proliferation in vitro. The present study examined the effect of all-tram retinoic acid (ATRA) and 13-cis retinoic acid (13-CRA) on intimal hyperplasia in the rat. Forty-two male Sprague-Dawley rats underwent standard balloon catheter
12
injury of the common carotid artery and were divided into the following groups: peanut oil, ATRA (24mg/kg, lOmg/kg, 5 mg/kg), 13-CRA (24 mg/kg, 10 mg/kg, 5 mg/kg). Morphometric analysis was performed on the arterial segments 21 days following injury. Serum retinoid levels were measured on all animals at the time of arterial injury to document drug delivery. Peak serum retinoid levels were achieved 2-3 h following dosing and the oral bioavailability of 13-CRA was 2-3 times greater than that of ATRA. Intimal medial area ratios (IWM) showed a 44% reduction (P = 0.0054) after treatment with 24 mg/kg ATRA and a 25% reduction (P = 0.058) after treatment with lOmg/kg ATRA. 13-CRA resulted in a 47% reduction (P = 0.0035) of IWM among animals receiving 24mg/kg and a 36% reduction (P = 0.0236) among those receiving lOmg/kg. No change in IH/M was detected after a dose of 5mg/kg of either retinoid. When neointimal mass was quantified by intimal internal elastic lamina area ratio (IWIEL) a dose-response suppression was again detected among animals given increasing doses of ATRA (P = 0.0399) and 13-CRA (P = 0.0142). External elastic laminal and luminal areas where significantly increased among animals receiving 10 mg/kg of either retinoid. Doses of 24 mg/kg and 5 mg/kg of either ATRA or 13-CRA showed no effect on vessel remodeling. In summary, retinoids appear to have two separate, yet interactive functions, in this arterial injury model. At high doses, retinoids suppress cellular proliferation resulting in a decrease in intimal mass and luminal stenosis. At lower doses, this antiproliferative effect is not as great, but an effect on remodeling exists which may be related to adventitial fibroblast or medial SMC differentiation.
3.5 Phospholipase A2 Stimulation in Endothelial C.B. SAISUDHAKER and B.E. SUMPIO, New Haven, Connecticut, USA
Cells EC
We have previously demonstrated that cyclic strain induces the production of prostacyclin in endothelial cell (EC). Arachidonic acid (AA), derived from the hydrolysis of membrane phospholipids by phospholipases A,, C and D, is hydrolyzed by cyclooxygenase to prostaglandins, prostacyclin and thromboxanes. Since PLA, is the major source of AA, we hypothesized that cyclic strain activates PLA, in EC. Methods: Bovine aortic EC, grown in flexible deformable culture plates, were subjected to 150mm Hg vacuum (10% average strain) at 60 cycles/min (0.5sec elongation, 0.5sec relaxation) for varying periods up to 500 sec. AA release was assayed using a 3H arachidonate labeled Escherichiu co/i suspension. Results were analyzed by ANOVA and Bonferroni’s modified t-test. cPLAz phosphorylation was analyzed by 32P1 prelabeling of the cells followed by immunoprecipitation with cPLA2 antibody. Results: The top figure shows that cyclic strain results in an increase in AA release attaining peak -ia . values, 143 c 10% of control, (n = 5, P M < 0.0005) at 250sec and decreasing to baseline at 500 sec. Western blots demoncB strated the Dresence of cPLA, in EC. The + “h bottom fighre demonstrates- that cPLA2 8 0- aoo4ooaco phosphorylation is time dependent with peakjntensity at 250 sec. Thus, cyclic strain stimulates AA release in EC and phosphor?3lfmsa ylates cPLAz in a parallel time frame.
CARDIOVASCULAR SURGERY SEPTEMBER 1997
World Congress of the ISCVS
3.3 Analysis of Microcirculatory Changes After Femorodistal Arterial Reconstructions G. KERESZTURY, S. SCHULTE and S. HORSCH, Cologne, Germany The aim of our prospective study was to register microcirculatory changes of the foot after femorodistal arterial reconstructions. Thirteen patients were included with P.A.O.D. grade II-IV, who were treated with primary femorodistal bypasses between 1 June 1996 and 1 October 1996. We performed the following measurements 1 week before and after surgery. (1) Transcutaneuos oxygen tension (TcP02) on the dorsum of the foot and thoracic wall and calculation of gradient (ATcPO,); (2) Laser Doppler floxmetry on the dorsum of the toe (L-Flux); (3) Vital capillary microscopy-videodensitometry of the toe (cap. dens.); (4) Vital capillary microscopy-red blood cell velocity (RFV) of the toe. Results:
ATcP02
L-Flux
Before After
35.4 13.7
18.1 20.8
cap. dens.
RFV
15.2 16.9
0.23 0.17
(1) The oxygen tension in the nutritive and shunt capillaries increased significantly; (2) There is a light increase of the circulation in the nutritive and shunt capillaries measured by L-Flux; (3) The density of the nutritive capillaries did not change after 1 week postoperatively; (4) The blood flow velocity in the nutritive capillaries remained unchanged. Our results show, that in the first 6 days after successful femorodistal bypasses there is a circulatory improvement in the shunt capillaries without any improvement in the nutritive capillaries.
3.4 Retinoic Acid Suppresses Intimal Hyperplasia and Prevents Vessel Remodeling Following Arterial Injury in the Rat ].R UMANA, I.D. DeROSE, ]R, 1.0. MADIGAN, J.H. PRYSTOWSKY, WS. BLANER, D. STERN, R. NOWYGROD, M.C.OZ and G.]. TODD, New York, New York, USA Retinoids are derivatives of vitamin A capable of binding to nuclear receptors and mediating the transcription of over 150 genes involved in cellular differentiation and proliferation. Retinoic acid receptors have been demonstrated in smooth muscle cells (SMC) which can bind retinoids and inhibit proliferation in vitro. The present study examined the effect of all-tram retinoic acid (ATRA) and 13-cis retinoic acid (13-CRA) on intimal hyperplasia in the rat. Forty-two male Sprague-Dawley rats underwent standard balloon catheter
12
injury of the common carotid artery and were divided into the following groups: peanut oil, ATRA (24mg/kg, lOmg/kg, 5 mg/kg), 13-CRA (24 mg/kg, 10 mg/kg, 5 mg/kg). Morphometric analysis was performed on the arterial segments 21 days following injury. Serum retinoid levels were measured on all animals at the time of arterial injury to document drug delivery. Peak serum retinoid levels were achieved 2-3 h following dosing and the oral bioavailability of 13-CRA was 2-3 times greater than that of ATRA. Intimal medial area ratios (IWM) showed a 44% reduction (P = 0.0054) after treatment with 24 mg/kg ATRA and a 25% reduction (P = 0.058) after treatment with lOmg/kg ATRA. 13-CRA resulted in a 47% reduction (P = 0.0035) of IWM among animals receiving 24mg/kg and a 36% reduction (P = 0.0236) among those receiving lOmg/kg. No change in IH/M was detected after a dose of 5mg/kg of either retinoid. When neointimal mass was quantified by intimal internal elastic lamina area ratio (IWIEL) a dose-response suppression was again detected among animals given increasing doses of ATRA (P = 0.0399) and 13-CRA (P = 0.0142). External elastic laminal and luminal areas where significantly increased among animals receiving 10 mg/kg of either retinoid. Doses of 24 mg/kg and 5 mg/kg of either ATRA or 13-CRA showed no effect on vessel remodeling. In summary, retinoids appear to have two separate, yet interactive functions, in this arterial injury model. At high doses, retinoids suppress cellular proliferation resulting in a decrease in intimal mass and luminal stenosis. At lower doses, this antiproliferative effect is not as great, but an effect on remodeling exists which may be related to adventitial fibroblast or medial SMC differentiation.
3.5 Phospholipase A2 Stimulation in Endothelial C.B. SAISUDHAKER and B.E. SUMPIO, New Haven, Connecticut, USA
Cells EC
We have previously demonstrated that cyclic strain induces the production of prostacyclin in endothelial cell (EC). Arachidonic acid (AA), derived from the hydrolysis of membrane phospholipids by phospholipases A,, C and D, is hydrolyzed by cyclooxygenase to prostaglandins, prostacyclin and thromboxanes. Since PLA, is the major source of AA, we hypothesized that cyclic strain activates PLA, in EC. Methods: Bovine aortic EC, grown in flexible deformable culture plates, were subjected to 150mm Hg vacuum (10% average strain) at 60 cycles/min (0.5sec elongation, 0.5sec relaxation) for varying periods up to 500 sec. AA release was assayed using a 3H arachidonate labeled Escherichiu co/i suspension. Results were analyzed by ANOVA and Bonferroni’s modified t-test. cPLAz phosphorylation was analyzed by 32P1 prelabeling of the cells followed by immunoprecipitation with cPLA2 antibody. Results: The top figure shows that cyclic strain results in an increase in AA release attaining peak -ia . values, 143 c 10% of control, (n = 5, P M < 0.0005) at 250sec and decreasing to baseline at 500 sec. Western blots demoncB strated the Dresence of cPLA, in EC. The + “h bottom fighre demonstrates- that cPLA2 8 0- aoo4ooaco phosphorylation is time dependent with peakjntensity at 250 sec. Thus, cyclic strain stimulates AA release in EC and phosphor?3lfmsa ylates cPLAz in a parallel time frame.
CARDIOVASCULAR SURGERY SEPTEMBER 1997