Table 2.
Heart rate (HR), QT interval (QT), QTcV interval (QTcV), mechanical systole (QLVPend) and electro-mechanical window (EMw) before and after HMR1556 (maximal 1.5 mg·kg−1 i.v.) and isoprenaline (2.5 µg·kg−1 i.v) in anaesthetized dogs (n = 20)
| HR (b.p.m.) | QT (ms) | QTcV (ms) | QLVPend (ms) | EMw (ms) | TdP (%) | |
|---|---|---|---|---|---|---|
| Baseline | 73 ± 3 | 252 ± 6 | 265 ± 5 | 339 ± 8 | 87 ± 7 | 0 |
| HMR1556 | 75 ± 5 | 319 ± 11† | 330 ± 10† | 348 ± 10 | 28 ± 12† | 0 |
| Isoprenaline | 160 ± 9† | 310 ± 8 | 362 ± 8† | 200 ± 6† | −109 ± 6† | 100 |
| Saline | 153 ± 12 | 369 ± 13 | 422 ± 13 | 223 ± 8 | −147 ± 20 | 100 |
| Mexiletine | 152 ± 15 | 301 ± 29 | 352 ± 26† | 175 ± 5† | −126 ± 27 | 100 |
| Atenolol | 108 ± 12† | 316 ± 21 | 353 ± 16† | 293 ± 11† | −23 ± 19† | 0 |
| Verapamil | 159 ± 26 | 255 ± 9† | 304 ± 4† | 240 ± 24 | −16 ± 17† | 0 |
After induction of Torsade de Pointes (TdP), dogs were defibrillated and treated with saline (1 mL·kg−1 i.v.; n = 5), mexiletine (5 mg·kg−1 i.v. n = 5), atenolol (0.5 mg·kg−1 i.v.; n = 5) or verapamil (0.4 mg·kg−1 i.v. n = 5).
Values are expressed as mean ± SEM.
Intergroup comparisons:
†
P < 0.05; ANOVA/Dunnett's test (two-sided, unpaired).