Table 1.
Cardiac activity of the tested compounds.
| Left Atrium | Right Atrium | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Negative Inotropy | Negative Inotropy | Negative Chronotropy | |||||||
| Cpd | Activity d | EC50 e(µM) | SEM | Activity f | EC50 e(µM) | SEM | Activity g | EC50 e(µM) | SEM |
| Nif | 97 ± 2.0 h | 0.26 | 0.19–0.36 | 85 ± 4.2 k | 0.039 | 0.031–0.051 | |||
| Lidofl | 65 ± 5.8 | 7.71 | 6.82–8.84 | 61 ± 1.7 j | 0.31 | 0.23–0.41 | 38 ± 1.5 | ||
| 1 a | 59 ± 0.5 | 0.72 | 0.67–0.79 | 89 ± 3.4 j | 1.01 | 0.78–1.30 | |||
| 2 a | 96 ± 2.3 | 0.058 | 0.052–0.070 | 77 ± 2.5 i | 0.16 | 0.11–0.23 | |||
| 3a b | 30 ± 1.7 h | 71 ± 3.1 j | 1.20 | 0.73–1.53 | |||||
| 4a | 62 ± 3.4 | 0.54 | 0.35–0.77 | 64 ± 1.7 k | 1.15 | 0.87–1.83 | 37 ± 2.3 m | ||
| 5a | 62 ± 3.7 h | 0.48 | 0.41–0.58 | 85 ± 1.3 | 1.09 | 0.89–1.22 | |||
| 3b b | 26 ± 2.3 h | 93 ± 2.1 i | 0.27 | 0.13–0.71 | |||||
| 4b | 79 ± 2.4 h | 0.26 | 0.21–0.34 | 61 ± 3.4 | 3.67 | 2.98–3.88 | |||
| 5b | 55 ± 3.1 | 0.97 | 0.54–1.55 | 88 ± 3.6 | 2.45 | 2.24–3.01 | |||
| 3c c | 65 ± 2.4 | 0.50 | 0.20–0.80 | 94 ± 4.6 j | 0.22 | 0.075–0.58 | |||
| 4c | 67 ± 3.4 h | 0.32 | 0.26–0.40 | 58 ± 2.4 | 1.62 | 1.06–2.46 | 38 ± 1.2 m | ||
| 5c | 78 ± 1.1 | 0.64 | 0.47–0.86 | 86 ± 2.2 | 1.15 | 0.89–1.32 | |||
| 3d c | 61 ± 3.6 | 0.24 | 0.17–0.30 | 89 ± 4.4 j | 0.20 | 0.14–0.28 | |||
| 4d | 34 ± 1.6 | 10 ± 0.7 | 32 ± 2.4 | ||||||
| 5d | 44 ± 0.1 | 55 ± 0.5 | 20.15 | 19.02–21.48 | |||||
| 3e c | 35 ± 2.9 | 47 ± 1.4 | 34 ± 2.1 j | ||||||
| 4e | 80 ± 2.4 i | 0.32 | 0.26–0.40 | 19 ± 0.3 | 7 ± 0.3 m | ||||
| 5e | 88 ± 1.6 h | 0.11 | 0.083–0.17 | 64 ± 2.4 n | 0.25 | 0.11–0.38 | |||
a Taken from ref. [11]. b Taken from ref. [12]. c Taken from ref. [13]. d Decrease in developed tension on isolated guinea-pig left atrium at 5 × 10−5 M, expressed as percent changes from the control (n = 5–6). The left atria were driven at 1 Hz. e Calculated from log concentration–response curves (Probit analysis by Litchfield and Wilcoxon [20] with n = 6–7). When the maximum effect was <50%, the EC50 inotropy and EC50 chronotropy values were not calculated. f Decrease in developed tension on a guinea-pig spontaneously beating isolated right atrium at 10−5 M, expressed as percent changes from the control (n = 7–8). g Decrease in atrial rate on a guinea-pig spontaneously beating isolated right atrium at 10−5 M, expressed as percent changes from the control (n = 7–8). Pretreatment heart rate ranged from 165 to 190 beats/min. The indicated concentrations in d, f, and g produce the maximum effect (M) for most compounds. For compounds that reach the maximum intrinsic activity at concentrations different from those indicated in “d”, “f”, and “g”, the maximum active concentration is indicated with a specific superscripted letter: h At 10−5 M. I At 10−6 M. j At 5 × 10−6 M. k At 5 × 10−5 M. l At 10−7 M. m At 5 × 10−5 M. n At 5 × 10−7 M. Bold: unpublished data. SEM: standard error of the mean. Nif (Nifedipine), Lidofl (lidoflazine).