The effects of vasodilators on the relaxation of guinea-pig aorta during acute recoil.
BACKGROUND
We have investigated the effects of various vasodilators on smooth muscle relaxation during acute recoil with guinea-pig aorta to find effective therapies to prevent acute recoil at percutaneous transluminal coronary angioplasty (PTCA).


METHODS
Muscle strips from guinea-pig aorta without endothelium were placed in a bath filled with modified Krebs solution. The strip was isotonically stretched with a tension of 9 mN for 1 min, and then isometric tension was measured until the tension reached a steady state. Various vasodilators were applied during isometric tension measurement.


RESULTS
When no drug was applied (control), isometric tension reached a steady state within 20 min. The steady state was approximately 10% lower (more relaxed) than the stretched level. When isosorbide dinitrate (ISDN, 1 mM) was applied during isometric measurement, 18.7+/-5.3% greater relaxation occurred than in control relaxation (P<0.05, n=5). When nicorandil (1 mM) was applied, the following relaxation was 18.6+/-5.7% greater than control (P<0.05, n=8). The simultaneous application of glibenclamide (1 mM) completely inhibited such additional relaxation by nicorandil. Application of nifedipine (10 microM) caused a 12.9+/-2.5% greater relaxation than control (P=0.066, n=4). The first metabolite of sarpogrelate (BP984, 10 microM) caused much greater relaxation than control (23.7+/-7.9%, P<0.05, n=6). Amlodipine (10 microM), phentolamine (10 microM), and sarpogrelate (10 microM) had no influence on the relaxation of the strip.


CONCLUSIONS
ISDN, nicorandil and BP984 significantly increase relaxation of the muscle strips after stretching compared to the control. These vasodilators may reduce acute recoil of the smooth muscle after PTCA.
Tanaka
Toshiro
T
First Department of Internal Medicine, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Japan. tanaka-t@med.nagoya-u.ac.jp
Iino
Shigeo
S
Takeshita
Kyosuke
K
Kondo
Takahisa
T
Hirai
Makoto
M
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D017311:Amlodipine / Q000494:pharmacology; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000503:physiopathology / Q000601:surgery*; D004195:Disease Models, Animal; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D007548:Isosorbide Dinitrate / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology / Q000601:surgery; D020108:Nicorandil / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011183:Postoperative Complications; D013386:Succinates / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D010975:Platelet Aggregation Inhibitors; D013386:Succinates; D014665:Vasodilator Agents; C064294:sarpogrelate; D017311:Amlodipine; D020108:Nicorandil; D009543:Nifedipine; D007548:Isosorbide Dinitrate; D010646:Phentolamine