2
.
6
. Drugs Bradykinin acetate, and 5-HT creatine sulfate, in-
domethacin and prostaglandin F2a were obtained from Sigma Chemical Co St Louis, MO; ketanserin bitar-
trate from Janssen Pharmaceutica, Beerse, Belgium; and NTG from Abbott Laboratories, IL. Bradykinin,
5-HT, NTG and prostaglandin F2a were dissolved in distilled water, indomethacin in supersatured TRIS-
base, and ketanserin in dimethyl sulfoxide DMSO, Sigma. All agonists are reported as molar concentra-
tion present in the organ chamber. For in 6i6o studies the drugs were infused diluted in 5 dextrose, and the
final molar concentration reported was estimated on basis of a 80 mlmin coronary blood flow.
2
.
7
. Statistical analysis The data were expressed as mean 9 SEM. Unless
otherwise stated, n refers to the number of arteries. As a normal distribution cannot be assumed for both
morphologic parameters and percent changes in vasore- activity,
the Kruskal – Wallis,
and Friedman
or Wilcoxon signed rank sum tests were used to compare
mean group values StatView 512™. For comparison of heart rate and blood pressure changes after drug
infusion, t-test correlated groups was used. A
P
value less than 0.05 was considered significant.
3. Results
3
.
1
. Vasoreacti6ity in 6i6o
3
.
1
.
1
. Dextrose Vasoresponses to 5 dextrose D5, a control vehi-
cle, observed in either normal or injured coronary arteries, were not significantly altered during the entire
period of this study Fig. 1.
3
.
1
.
2
. Bradykinin Following the infusion of bradykinin in noninjured
coronary arteries, a significant increase in vessel diame- ter was observed Fig. 1.
After balloon injury, vasodilatation to this agent was significantly attenuated during the first 2 weeks remain-
ing comparable to control arteries after this period Table 1.
3
.
1
.
3
. Serotonin The highest dose of 5-HT caused significant vasocon-
striction in control arteries Fig. 1. Vasoresponses to 5-HT after coronary angioplasty did not show signifi-
cant changes except at 12 weeks, when the vasoconstric- tion elicited by this agent was significantly higher
Table 1.
3
.
1
.
4
. Nitroglycerin The NO-donor NTG induced significant vasodilation
in normal coronary arteries Fig. 1. However, after coronary balloon angioplasty, vasoresponse to this en-
dothelium-independent agent was impaired until the first week. After this period, vasodilatation following
NTG was comparable to that obtained in control arter- ies Table 1.
During in vivo experiments there was a significant increase in heart rate only after BK and 5-HT. Mea-
surements of systolic and diastolic blood pressure showed a significant decrease after BK Table 2.
3
.
2
. Vasoreacti6ity in 6itro
3
.
2
.
1
. Bradykinin The values for vasorelaxation obtained to BK in
noninjured rings showed the classical dose-response curve Fig. 2.
Vasoreactivity studies performed in ballooned rings showed endothelial dysfunction in response to BK dur-
ing the whole period of follow-up Fig. 2. E
max
values obtained were also reduced during the same time-points
Table 3.
3
.
2
.
2
. Serotonin As observed for BK, the vasoresponses to the en-
dothelium-dependent 5-HT in control rings showed the classical dose-response curve Fig. 2.
The endothelium-dependent relaxation to 5-HT was reduced in the injured rings up to 12 weeks after the
coronary intervention when compared to control rings. E
max
values for this drug remained reduced after bal- loon angioplasty Table 3.
3
.
2
.
3
. Nitroglycerin This endothelium-independent agent also promoted
the classical dose-response curve in noninjured rings, and E
max
values for this agent did not differ from those observed for control rings Table 3.
Table 3 Assessment of maximal relaxation E
max
produced by BK, serotonin, and NTG in coronary rings after the intervention
a
Group n
NTG 5-HT
BK 122.6 9 7.2
99.5 9 4.2 14
Control 72.1 9 7.4
116.9 9 6.7 4
35.3 9 6.9 50.6 9 1.6
1 day 11.9 9 1.7
146.3 9 11.9 33.9 9 7.4
1 week 5
7 128.4 9 11.2
2 weeks 31.1 9 6.9
53.7 9 13.6 52.4 9 9.9
33.5 9 10.3 4 weeks
144.8 9 17.5 4
4 45.67 9 10.6
108.2.5 9 3.1 8 weeks
23.1 9 5.2 103.1 9 3.7
15.4 9 3.3 48.1 9 8.6
6 12 weeks
a
Values are percent changes after maximal PGF2a-induced con- traction plotted in the Kaleidograph software mean 9 SEM and n
refers to number of arteries. Higher E
max
value , P = 0.0001 Kruskal–Wallis test for E
max
comparisons of each drug between time-points.
Fig. 3. Cross-sections of porcine coronary arteries. A, B, and C are control specimens showing integrity of vessel layers and complete endothelial coverage. D, E, and F are 2-week specimens showing intimal thickening and partial endothelial coverage. G, H, and I are 4-week specimens
showing complete endothelial regeneration. J, K, and L are 12-week specimens showing important intimal proliferation at the site of IEL rupture. A, D, G, and J are CME × 40; B, E, H, and K are DBA × 40; C, F, I, and L are DBA magnifications × 400.
3
.
3
. Morphology Oversized coronary balloon angioplasty caused deep
vascular injury characterized by an extensive endothe- lial denudation, disruption of the internal elastic lamina
IEL, and thrombus formation. After 2 weeks large luminal areas remained without endothelium, thrombi
were still present, and areas of intimal thickening were observed, specially at the site of IEL rupture Fig. 3.
Histomorphometric analysis showed reduced presence of endothelium-positive staining by DBA at 1 day, and
at 1 and 2 weeks after balloon angioplasty when com- pared to control, noninjured segments 1 day 28.4 9
9.9; 1 week 44.8 9 5.8; 2 weeks, 53.3 9 4.7; 4 weeks 93.4 9 5.4; 8 weeks 92.8 9 3.4; 12 weeks
89.8 9 4.5. Largely complete regeneration of the en- dothelial layer was observed 4 weeks after balloon
injury Fig. 4.
Intima, media and intimamedia ratios were also quantified after the complete endothelium regeneration.
Table 4 shows that the thickness of the vessel wall increased progressively up to 12 weeks.
Fig. 4. Endothelial coverage. Data were obtained from percentages of DBA-labelled luminal perimeters obtained in control specimens. Coronary specimens were examined in a blinded fashion control n = 19, 1 day n = 9, 1 week n = 10, 2 week n = 19, 4 week n = 13, 8 week n = 13, 12 week
n = 20. The amount of endothelium present was reduced in the short-term follow-up. lower endothelial coverage, Kruskal – Wallis test.
4. Discussion
