Coronary Balloon Injury Research Articles

Chinese medicine Fufang Zhenzhu Tiaozhi capsule ameliorates coronary atherosclerosis in diabetes mellitus-related coronary heart disease minipigs

BackgroundDiabetes mellitus-related coronary heart disease (DM-CHD) is the most common cause of death in diabetic patients. Various studies have shown that Chinese medicine Fufang-Zhenzhu-Tiaozhi capsule (FTZ) has therapeutic effects on cardiovascular diseases. More research is required to determine the mechanism of FTZ protection against coronary atherosclerosis. ObjectiveTo investigate the unique mechanism of FTZ in treatment of DM-CHD minipigs with coronary atherosclerosis. MethodsHigh-fat/high-sucrose/high-cholesterol diet combined with streptozotocin and coronary balloon injury were used to induce DM-CHD minipig model, which was then randomly divided into: DM-CHD model, DM-CHD treated with FTZ or positive drug (Metformin + Atorvastatin, M+A). After twenty-two weeks, ultrasonography, electrocardiography, and image detection were employed to detect cardiac functions and assess coronary artery stenosis and plaque. Human umbilical vein endothelial cells (HUVECs) were treated high glucose or/and FTZ. Pigs tissues and treated-cells were collected for further testing. ResultsIn DM-CHD minipigs, FTZ treatment significantly reduced disordered glycolipid metabolism similar as M+A administration. FTZ and M+A also alleviated coronary stenosis and myocardial injury. In addition, IκB and NF-κB phosphorylation levels, as well as the protein levels of IL-1β, Bax, cleave-Caspase 3, Bcl-2, and α-SMA were dramatically increased in the DM-CHD coronary artery, whereas CD31 and VE-cadherin expressions were decreased. Similar to M+A, FTZ reversed these protein levels in the DM-CHD coronary artery. Furthermore, FTZ ameliorated the damage and high migration activity of HUVECs induced by high glucose. ConclusionsFTZ improves coronary atherosclerosis through modulating inflammation, alleviating apoptosis, and inhibiting EndMT of coronary artery to protects against DM-CHD.

KCa3.1 contributes to atherosclerotic lesion development induced by low, oscillatory flow

Increased expression of KCa3.1 has been found in vascular smooth muscle (VSM), macrophages and T cells in atherosclerotic lesions from humans and mice. Proliferating VSM cells increase expression of KCa3.1, such that it becomes a dominant K+ channel and contributes to VSM cell migration. Previously, we showed that the KCa3.1 inhibitor, TRAM‐34, could inhibit coronary neointimal development following coronary balloon injury in swine. In the current study, we tested the role of KCa3.1 in atherosclerotic lesion development using two mouse models of atherosclerosis. First, partial carotid ligation (PCL), which produces a low, oscillatory (i.e. atheroprone) flow pattern in the left carotid artery was performed on 6–8 week old male Apoe−/− mice. Mice were subsequently placed on a Western diet (WD; TD.88137, Teklad) for 4 weeks and received daily s.c. injections of TRAM‐34 (120 mg/kg) or equal volumes of vehicle (peanut oil). To directly test the role of KCa3.1 we used CRISPR/Cas9 to generate KCa3.1−/−Apoe−/− (DKO) mice. Subsequently, we examined lesion development in the brachiocephalic artery (BCA) of DKO vs. Apoe−/− male mice on a WD for 3 months. In PCL mice, TRAM‐34 treatment reduced lesion size ~50% (p<0.05). In addition, lesions from TRAM‐34 treated mice contained significantly less collagen (6 ± 1% v. 15 ± 2%; p<0.05), fibronectin (14±3% v. 32±3%; p<0.05) and smooth muscle content (19±2% v. 29±3%; p<0.05). Similarly, in BCAs of DKO mice, both lesion size (0.036 vs. 0.118 mm2, p<0.05) and relative stenosis (13.9% vs. 43.0%, p<0.05) were reduced 70% compared to Apoe−/− mice with no effect on medial or lumen area. Neither TRAM‐34 nor KCa3.1 silencing had any effect on total cholesterol or body weight. These data provide the first genetic validation defining a major role of KCa3.1 in lesion development and determining smooth muscle and matrix content of atherosclerotic lesions.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A new rapamycin-abluminally coated chitosan/heparin stent system accelerates early re-endothelialisation and improves anti-coagulant properties in porcine coronary artery models.

Drug-eluting stents (DES) in percutaneous coronary intervention are more effective in preventing in-stent restenosis compared with bare metal stents (BMS); however, DES may cause late stent thrombosis, which has limited its use. In this study, the functional properties of a newly developed DES (RAP/CS/HEP), in which rapamycin was abluminally-loaded onto a chitosan/heparin coating stent (CS/HEP), were investigated in large animal artery injury models. The effectiveness of BMS, RAP (the traditional version of rapamycin DES), CS/HEP and RAP/CS/HEP stents in preventing coagulation and promoting re-endothelialisation was examined and compared in the porcine coronary artery models with arteriovenous shunt, high load thrombus and coronary balloon injury at day 7 and 28, respectively, after stent implantation. The re-endothelialisation on these stents was further evaluated in terms of endothelial gene expression using quantitative RT-PCR. In the porcine coronary artery injury models, both RAP and RAP/CS/HEP stents were potent in reducing neointimal thickness, thus enlarging lumen area efficiently in the stented artery region compared with BMS and CS/HEP. RAP/CS/HEP stents facilitated re-endothelialisation and inhibited thrombosis more efficiently than BMS and RAP. Consistent with this, the expression of endothelial genes, such as CD31, CD34, eNOS and VEGF, was significantly elevated with RAP/CS/HEP stents compared with RAP and BMS stents. Abluminal coating of rapamycin onto the endothelialisation-accelerated CS/HEP stent and may prove to be an efficient treatment for tackling the late stent thrombosis associated with the traditionally circumferential RAP stent. This new RAP/CS/HEP stent system exhibits considerably improved therapeutic activity.

Effects of local delivery of Tetradecylthioacetic acid within the injured coronary vessel wall

Objectives. Inflammation is involved in cell proliferation and collagen deposition causing vessel wall remodeling and restenosis after plain balloon angioplasty. Local drug delivery of bioactive agents that reduce the incidence of adverse wall remodeling is of considerable interest concerning treatment strategies for coronary vessel disease and could alter the need of repeated revascularization. Design. In this study, 34 domestic pigs undergoing coronary balloon injury were randomly assigned to Tetradecylthioacetic acid (TTA) or placebo delivered locally. After four weeks, vessel wall collagen density, inflammatory markers and lipid fractions were assessed as well as cell proliferation. Results. Collagen particle count was lower after TTA compared to placebo, 177 ± 11 n/area versus 225 ± 13 n/area (p = 0.007). Interleukin-2 (IL-2) concentration was reduced, 1.6 ± 0.02 pg/ml versus 2.6 ± 0.5 pg/ml, (p = 0.01). The anti-inflammatory index was increased after TTA, 46.28 ± 12.1 versus 34.66 ± 4.5, (p = 0.025). There were no differences between TTA and placebo with regard to cell proliferation. Conclusions. Local delivery of TTA reduced the local inflammatory response and collagen accumulation. Local balloon delivery of TTA into the vessel wall may represent an alternative antiproliferative strategy for preventing restenosis, in particular for vessels with obstructive disease not available for stent implantation.

Endogenous testosterone attenuates neointima formation after moderate coronary balloon injury in male swine.

Previous studies from our laboratory have demonstrated that testosterone increases coronary smooth muscle protein kinase C delta (PKC delta) both in vivo and in vitro and inhibits coronary smooth muscle proliferation by inducing G(0)/G(1) cell cycle arrest in a PKC delta-dependent manner. The purpose of the present study was to determine whether endogenous testosterone limits coronary neointima (NI) formation in a porcine model of post-angioplasty restenosis. Sexually mature, male Yucatan miniature swine were either left intact (IM), castrated (CM), or castrated with testosterone replacement (CMT; Androgel, 10 mg/day). Angioplasty was performed in both the left anterior descending and left circumflex coronary arteries with balloon catheter overinflation to induce either moderate (1.25-1.3 x diameter; 3 x 30 s) or severe (1.4x diameter; 3 x 30 s) injury, and animals were allowed to recover for either 10 or 28 days. Injured coronary sections were dissected, fixed, stained (Verheoff-Van Gieson, Ki67, PKC delta, p27), and analysed. Vessels without internal elastic laminal rupture were excluded. Following moderate injury, intimal area, intima-to-media ratio (I/M), and I/M normalized to rupture index (RI) were increased in CM compared with IM and CMT. RI, medial area, and intimal/medial thickness (IMT) were not different between groups. NI formation was inversely related to serum testosterone concentration. Conversely, following severe injury, there were no significant differences between the groups. Testosterone inhibited proliferation and stimulated PKC delta and p27(kip1) expression during NI formation (10 days post-injury). These findings demonstrate that endogenous testosterone limits coronary NI formation in male swine and provides support for a protective role for testosterone in coronary vasculoproliferative diseases, such as restenosis and atherosclerosis.

Functional properties of a novel mutant of staphylokinase with platelet-targeted fibrinolysis and antiplatelet aggregation activities

The present study was performed to characterize the functional properties of RGD-SAK, a novel mutant of staphylokinase (SAK). Biochemical analysis indicated that RGD-SAK maintained the similar structure and the fibrinolytic function of SAK. Measurement of platelet binding activity in vitro demonstrated that RGD-SAK had a much higher affinity with platelets than SAK. In vitro platelet-rich clot lysis assay demonstrated that the engineered mutant outperformed the non-manipulated SAK. The time required for 50% platelet-rich clot lysis was reduced significantly across different concentrations of RGD-SAK comparing with SAK. Meanwhile, RGD-SAK was found to inhibit ADP-induced platelet aggregation in a concentration-dependent manner while SAK had negligible effect on platelet aggregation. In concordance, further study in a porcine coronary balloon injury model demonstrated the efficacy of RGD-SAK for the lysis of platelet-rich coronary blood clots and for the prevention of reocclusion after thrombolysis. These results suggested that RGD-SAK may serve as a potential thrombolytic agent with platelet-targeted fibrinolysis and antiplatelet aggregation activities.

IKCa1 is an immediate early response gene mediating coronary smooth muscle phenotypic modulation

We previously demonstrated functional upregulation of intermediate-conductance Ca2+-activated K+ channel (IKCa1) with the development of early coronary atherosclerosis in vivo and as a prerequisite for platelet-derived growth factor BB (PDGF-BB) induced porcine coronary smooth muscle cell (CSMC) dedifferentiation and migration in vitro. Our objective was to examine the temporal regulation of IKCa1 and smooth muscle marker gene expression in porcine CSMC exposed to coronary balloon injury (CBI) in vivo or PDGF-BB in vitro. Two hours following CBI, laser capture microdissection of media from injured vessels demonstrated higher IKCa1, c-jun, and c-fos, but unaltered amounts of SMMHC mRNA compared to control media. PDGF-BB increased enrichment of H4 acetylation and c-jun to the AP-1 binding site of the IKCa1 promoter ~4-fold, an effect blocked by TRAM-34, a specific IKCa1 channel blocker. PDGF-BB increased IKCa1 and decreased myocardin mRNA at 30 minutes, but did not decrease smooth muscle myosin heavy chain (SMMHC) or smoothelin expression until 10 hours. In conclusion, these data indicate that AP-1 dependent upregulation of IKCa1 is an immediate and requisite factor initiating smooth muscle specific gene suppression, i.e. CSMC phenotypic modulation, during coronary injury. Supported by: NIH HL52490

Effects of SolCD39, a Novel Inhibitor of Platelet Aggregation, on Platelet Deposition and Aggregation after PTCA in a Porcine Model

This study evaluated CD39 in a porcine model of balloon angioplasty and in plasma of patients undergoing percutaneous intervention. CD39 (E-NTPDase1), is the endothelial ecto-ADPase inhibiting platelet function via hydrolysis of released platelet ADP. A recombinant soluble form of CD39 (solCD39) given intravenously to pigs had an elimination half life of 5--7 days, increased the bleeding time to an extent similar to aspirin, and inhibits platelet aggregation by>90%. Platelet counts and clot retraction remained normal following solCD39 administration. In a pig model of acute coronary balloon injury, solCD39 resulted in non-statistically significant decreases in platelet (7.7+/-1.4 versus 11.7+/- 3.4) and fibrin (3.5+/- 0.4 versus 4.2+/- 0.7) deposition ratios. Adding ex vivo to human platelet rich plasma (PRP) solCD39 produced nearly 100% inhibition of ADP-induced platelet aggregation. A dose-response effect of solCD39 on platelet aggregation induced by collagen or a thrombin receptor activating peptide (TRAP(SFLLRN)) was noted in PRP obtained from volunteers and patients receiving aspirin, clopidogrel or ticlopidine. SolCD39 also provided additional and complete inhibition of TRAP-induced platelet aggregation in PRP from patients who had received abciximab, aspirin and clopidogrel. SolCD39, a novel inhibitor of platelet activation and recruitment with a relatively long half-life appears to be well tolerated and is a potent inhibitor of ADP-, collagen-, or TRAP-induced platelet activation. Its potential use in percutaneous coronary intervention requires further study. ABBREVIATED ABSTRACT: E-NTPDase1/CD39 is the endothelial ecto-ADPase responsible for inhibition of platelet function. A recombinant soluble form (solCD39) had an elimination half life of 5-7 days in pigs, elevated bleeding times similar to aspirin, did not affect clot retraction, and inhibited platelet aggregation by > 90%. When combined with standard heparin therapy in a pig model of acute coronary balloon injury, solCD39 resulted in a trend toward a decrease in platelet and fibrin deposition. SolCD39 added ex vivo to human platelet rich plasma yielded nearly 100% inhibition of ADP-induced platelet aggregation and provided further inhibition when combined with standard therapy.

Effect of adventitial VEGF(165) gene transfer on vascular thickening after coronary artery balloon injury.

Experimental studies have provided evidence that neovascularization is an important feature of plaque growth, and angiogenic gene therapy may, therefore, increase plaque growth. This study examined the effect of local (peri)adventitial vascular endothelial growth factor165 (VEGF) gene transfer on vascular thickening after coronary balloon injury. Two coronary arteries of 15 pigs were subjected to balloon injury followed by either (peri)adventitial VEGF165 or beta-galactosidase (LacZ) plasmid/liposome-mediated gene transfer via needle injection catheter. At days 3, 14 and 28, histologic sections of coronary arteries were analyzed. Transferred VEGF165 gene and increased adventitial neovascularization were detected in coronary arteries after balloon injury and VEGF injection. The mean intima+media (I+M) area increased after coronary balloon injury and VEGF (1.13+/-0.17 and 2.54+/-0.52 mm(2)) or LacZ (1.37+/-0.19 and 2.96+/-0.41 mm(2)) gene transfer, with no significant difference between both groups at 3 and 28 days, respectively. No significant difference in I+M neovascularization was observed at day 28 between the treatment groups (microvessel area density 0.24+/-0.08% with VEGF and 0.26+/-0.14% with LacZ, respectively). I+M endothelial cell proliferation index ranged from 7% to 22% (VEGF) and 18% to 24% (LacZ). Catheter-mediated (peri)adventitial VEGF165 gene transfer induces adventitial neovascularization but not an increase of vascular thickening/I+M growth and vascularization in a porcine model of coronary artery injury.

Short-term local delivery of an inhibitor of Ras farnesyltransferase prevents neointima formation in vivo after porcine coronary balloon angioplasty.

Mitogenic stimuli present at the site of coronary arterial balloon injury contribute to the progression and development of a restenotic lesion, many signaling through a common pathway involving the small G protein p21(ras). Our aim was to demonstrate in biochemical studies that farnesyl protein transferase inhibitor III (FPTIII) is an inhibitor of p21(ras) processing and that when it is given locally in vivo at the site of coronary balloon injury in a porcine model, it can inhibit neointima formation. FPTIII (1 to 25 micromol/L) concentration-dependently reduced p21(ras) levels in porcine coronary artery smooth muscle cell membranes. FPTIII also prevented p42/p44 MAPK activation and DNA synthesis in response to platelet-derived growth factor in these cells at a concentration of 25 micromol/L. Application of 25 micromol/L FPTIII locally for 15 minutes to balloon-injured porcine coronary arteries in vivo prevented neointima formation assessed at 4 weeks, reduced proteoglycan deposition, and inhibited adventitial hypertrophy. Coronary arteries from FPTIII-treated pigs had no deterioration in contraction or in endothelium-dependent relaxation. The study demonstrates in the pig that short-term local delivery of inhibitors of p21(ras)-dependent mitogenic signal transduction prevents restenosis after balloon angioplasty.

Effect of xiongshao capsule on vascular remodeling in porcine coronary balloon injury model

To study the effect of Xiongshao Capsule (XS) on vascular remodeling in porcine coronary balloon injury model. Restenosis model was established by oversized balloon injury at mid-region of the left anterior descending coronary artery. The effect of drugs on late lumen loss and vascular remodeling was evaluated with quantitative histological method by combining results from histopathological analysis and coronary arteriography. Vascular remodeling explained (59 +/- 20)% of late lumen loss. All drugs significantly reduced late lumen loss 4 weeks after balloon injury (P < 0.05 or 0.01). Both low-dose and high-dose XS markedly reduced late lumen loss resulting from vascular remodeling, as compared with the control group (P < 0.05 and P < 0.01 respectively). Vascular remodeling played an important role in late lumen stenosis after balloon injury of coronary artery. XS could significantly inhibit pathological vascular remodeling after balloon injury, thus reduce late lumen loss and prevent restenosis.

Adventitial vasa vasorum in balloon-injured coronary arteries: visualization and quantitation by a microscopic three-dimensional computed tomography technique.

The objective of this study was to examine the quantitative response of the adventitial vasa vasorum to balloon-induced coronary injury. Recent attention has focused on the role of vasa vasorum in atherosclerotic and restenotic coronary artery disease. However, the three-dimensional anatomy of these complex vessels is largely unknown, especially after angioplasty injury. The purpose of this study was to visualize and quantitate three-dimensional spatial patterns of vasa vasorum in normal and balloon injured porcine coronary arteries. We also studied the spatial growth of vasa vasorum in regions of neointimal formation. A novel imaging technique, microscopic computed tomography, was used for these studies. Four pigs were killed 28 d after coronary balloon injury, and four pigs with uninjured coronary arteries served as normal controls. The coronary arteries were injected with a low-viscosity, radiopaque liquid polymer compound. Normal and injured coronary segments were scanned using a microscopic computed tomography technique. Three-dimensional reconstructed maximum intensity projection and voxel gradient shading images were displayed at different angles and voxel threshold values, using image analysis software. For quantitation, seven to 10 cross-sectional images (40 normal and 32 balloon injured cross-sections) were captured from each specimen at a voxel size of 21 microm. Normal vasa vasorum originated from the coronary artery lumen, principally at large branch points. Two different types of vasa were found and classified as first-order or second-order according to location and direction. In balloon-injured coronary arteries, adventitial vasa vasorum density was increased (3.16+/-0.17/mm2 vs. 1.90+/-0.06/mm2, p = 0.0001; respectively), suggesting neovascularization by 28 d after vessel injury. Also, in these injured arteries, the vasa spatial distribution was disrupted compared with normal vessels, with proportionally more second-order vasa vasorum. The diameters of first-order and second-order vasa were smaller in normal compared with balloon-treated coronary arteries (p = 0.012 first-order; p < 0.001, second-order; respectively). The density of newly formed vasa vasorum was proportional to vessel stenosis (r = 0.81, p = 0.0001). Although the total number of vasa was increased after injury, the total vascular area comprised of vasa was significantly reduced in injured vessels compared with normals (3.83+/-0.20% to 5.42+/-0.56%, p = 0.0185). Adventitial neovascularization occurs after balloon injury. The number of new vessels is proportional to vessel stenosis. These findings may hold substantial implications for the therapy of vascular disease and restenosis.

Vitamins C and E inhibit O2- production in the pig coronary artery.

We previously found in a pig coronary balloon injury model that vitamins C and E as well as probucol had beneficial effects on the vessel response to injury measured by morphometry These effects correlated with an inhibition in the ability to oxidize LDLs ex vivo, suggesting that the morphological response was due to the antioxidant effect of the treatments. In the present study, the production of O2- by vessels 14 days after balloon injury was determined and correlated with circulating and tissue levels of vitamins C and E. Twenty-five domestic pigs were divided into four groups: control (n=7), vitamin C (500 mg/d, group C, n=6), vitamin E (1000 IU/d, group E, n=6), and vitamins C and E (500 mg/d and 1000 IU/d, group C+E, n=6). Vitamins were administered 7 days before oversized balloon injury of the left anterior descending coronary artery (LAD) and continued for 14 days after injury. Vitamin C and E concentrations were determined in plasma and lymphocytes as an index for tissue levels. Vessels were harvested after animals were killed, and O2- production was measured by lucigenin chemiluminescence. O2- production by the injured LAD was 2.5-fold greater than O2- production by the uninjured LAD or right coronary artery (RCA). The increase in O2- was caused primarily by cells present in the media and neointima. All vitamin-treated groups showed significantly decreased O2- production in both the RCA and LAD (approximately 45% inhibition) relative to vessels in the control, untreated group. There was a significant correlation between LAD O2- production and lymphocyte vitamin E levels. The present study is the first to show increased O2- production in injured vessels and to demonstrate that antioxidant vitamins reduce O2- production. These results suggest that beneficial effects of antioxidant vitamins in coronary artery disease are related, in part, to alterations in vessel redox state.

Quantitative evaluation of local drug delivery using the InfusaSleeve catheter

Background Restenosis is the most common long-term complication after angioplasty. Local delivery of pharmacologic agents at the site of angioplasty holds promise as a means of achieving higher concentrations of drug in the arterial wall than can be obtained by systemic infusion. In this study, a novel local drug delivery catheter system, the InfusaSleeve™ catheter, was evaluated in a porcine coronary balloon injury model. The purpose of the study was to evaluate the efficacy of solute transfer to the arterial wall and the influence of varying supporting angioplasty balloon pressure. Methods and Results: Ten pigs (total of 22 arterial segments) underwent overstretch balloon injury (artery/balloon ratio 1:1.29) with a standard angioplasty balloon. In 7 animals (16 arterial segments) horseradish peroxidase (HRP; 10 mg/ml) was administered locally after injury, by tracking the local infusion catheter as a sheath over the angioplasty balloon to the intended site of arterial drug delivery. Supporting angioplasty balloons were inflated to one of the three different pressures. In 3 pigs HRP (10 mg/ml) was administered intravenously. No significant arterial injury caused by the local delivery device was evident on histological examination (disruption of the internal lamina elastica, arterial media, or thrombosis). Radial concentrations of the HRP reaction product in the first 150 μm of the arterial wall were quantified against known standards by measurement of light transmission through tissue sections. Mean HRP concentrations were not significantly different from those obtained by intravenous infusion using a supporting pressure of 1 atm or a supporting pressure of 3 atm of the underlying angioplasty balloon. However, a supporting pressure of 6 atm resulted in a 6-fold greater mean HRP concentration in the arterial wall than that which could be achieved by systemic administration of an equal volume of tracer (P < 0.001). Conclusion Thus solute can be delivered throughout the coronary media by the InfusaSleeve, with the magnitude of wall uptake related to support pressure. Local delivery at 6 atm support pressure produced substantially greater uptake than did systemic delivery. Cathet. Cardiovasc. Diagn. 42:102–108, 1997. © 1997 Wiley-Liss, Inc.

Quantitative evaluation of local drug delivery using the InfusaSleeve catheter.

Restenosis is the most common long-term complication after angioplasty. Local delivery of pharmacologic agents at the site of angioplasty holds promise as a means of achieving higher concentrations of drug in the arterial wall than can be obtained by systemic infusion. In this study, a novel local drug delivery catheter system, the InfusaSleeve catheter, was evaluated in a porcine coronary balloon injury model. The purpose of the study was to evaluate the efficacy of solute transfer to the arterial wall and the influence of varying supporting angioplasty balloon pressure. Ten pigs (total of 22 arterial segments) underwent overstretch balloon injury (artery/balloon ratio 1:1.29) with a standard angioplasty balloon. In 7 animals (16 arterial segments) horseradish peroxidase (HRP; 10 mg/ml) was administered locally after injury, by tracking the local infusion catheter as a sheath over the angioplasty balloon to the intended site of arterial drug delivery. Supporting angioplasty balloons were inflated to one of the three different pressures. In 3 pigs HRP (10 mg/ml) was administered intravenously. No significant arterial injury caused by the local delivery device was evident on histological examination (disruption of the internal lamina elastica, arterial media, or thrombosis). Radial concentrations of the HRP reaction product in the first 150 microns of the arterial wall were quantified against known standards by measurement of light transmission through tissue sections. Mean HRP concentrations were not significantly different from those obtained by intravenous infusion using a supporting pressure of 1 atm or a supporting pressure of 3 atm of the underlying angioplasty balloon. However, a supporting pressure of 6 atm resulted in a 6-fold greater mean HRP concentration in the arterial wall than that which could be achieved by systemic administration of an equal volume of tracer (P < 0.001). Thus solute can be delivered throughout the coronary media by the InfusaSleeve, with the magnitude of wall uptake related to support pressure. Local delivery at 6 atm support pressure produced substantially greater uptake than did systemic delivery.

Combination of vitamins C and E alters the response to coronary balloon injury in the pig.

Restenosis is the major limitation of the long-term success of percutaneous transluminal coronary angioplasty. The process of restenosis involves repair of vascular injury and remodeling of vessel architecture. Therapeutic interventions that improve vascular function may therefore be beneficial in the treatment of restenosis. Antioxidants such as probucol and vitamins C and E have proved effective in improving endothelial function in hypercholesterolemia, inhibiting lipid accumulation in animal models of atherosclerosis, and decreasing cardiovascular mortality in humans. Forty-two female domestic swine were divided into four study groups: control (n = 12); vitamin C (500 mg/d, group C, n = 9); vitamin E (1000 U/d, group E, n = 10); and vitamins C and E (500 mg/d + 1000 U/d, group C+E, n = 11) before oversized balloon injury of the left anterior descending and circumflex coronary arteries. Vitamins were administered 7 days before balloon injury and continued until the swine were killed 14 days after injury. Significant differences in morphometric parameters were present only in group C+E, with increases in vessel and lumen area in the segment with maximal injury. Although there was no decrease in intima area or in maximal intima thickness, the ratio of intima area to vessel area was significantly reduced, consistent with a positive effect in group C+E. Graphic analysis of the relationship between initial vessel injury (using internal elastic lamina fracture length/lumen perimeter) and vessel response to injury (using intima area/vessel area) for all segments showed improved indices for group C+E (P < .005). The beneficial effect of vitamins correlated with changes in lipid redox state. Low-density lipoprotein (LDL) thiobarbituric acid-reactive substances showed an approximately 70% decrease in all treatment groups, and the lag phase for LDL-conjugated diene formation was significantly increased, with group C+E > group E > group C. The combination of vitamins C and E improved vascular response to injury because of an apparent beneficial effect on vascular remodeling. The fact that the combination of vitamins C+E was better than vitamin E or vitamin C alone is consistent with the ability of vitamin C to improve the antioxidant effect of vitamin E, suggesting that the improved vessel response was due to a change in redox state. This study suggests an important role for oxygen radicals in the vascular response to injury and suggests that vascular remodeling and intimal proliferation are important to the restenotic process.

Role of protein kinase C-mediated pathway in the pathogenesis of coronary artery spasm in a swine model.

The intracellular mechanism of coronary artery spasm is still unknown. The pathway mediated by protein kinase C (PKC) is an important intracellular process of various cellular responses, including vascular smooth muscle contraction. Thus, we examined the role of the PKC-mediated pathway in the pathogenesis of coronary artery spasm in our in vivo swine model. Seven Göttingen miniature pigs underwent coronary balloon injury and x-ray irradiation to induce atherosclerotic lesion. After 6 to 18 months, intracoronary serotonin (3 micrograms/kg) or histamine (3 micrograms/kg) repeatedly induced coronary artery spasm at the atherosclerotic site. At the spastic site, intracoronary administration of phorbol-12,13-dibutyrate (PDBu) (10(-9) mol/kg), a PKC-activating phorbol ester, also induced coronary artery spasm, which was completely blocked by pretreatment with intracoronary staurosporine (10 micrograms/kg), a PKC inhibitor. Intracoronary administration of an inactive phorbol ester, phorbol-12,13-didecanoate (10(-9) mol/kg), did not induce coronary vasoconstriction. Coronary artery spasm induced by the autacoids was significantly augmented by pretreatment with intracoronary PDBu and partially inhibited by staurosporine. Intracoronary administration of Bay K 8644 (10 micrograms/kg), a dihydropyridine-sensitive L-type calcium channel agonist, also induced coronary artery spasm at the spastic site, which was significantly inhibited by pretreatment with intracoronary staurosporine or nifedipine (0.1 mg/kg). These results suggest (1) the PKC-mediated pathway is importantly involved in the pathogenesis of coronary artery spasm, (2) activation of the PKC-mediated pathway partially accounts for serotonin- and histamine-induced coronary artery spasm, and (3) at the spastic site, calcium influx through dihydropyridine-sensitive L-type calcium channel and/or calcium sensitivity of the contractile proteins may be augmented by the PKC-mediated pathway.