Temporal characteristics of pacing-evoked Ca2+ transients in control cells and in cells superfused with agonist
| . | Time to reach amplitude peak . | . | . | Time of decay . | . | . | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| . | t0 (milliseconds) . | t1440 (milliseconds) . | t1440:t0 ratio . | t0 (milliseconds) . | t1440 (milliseconds) . | t1440:t0 ratio . | ||||
| Control | 54±2.1 | 68±2.9 | 0.79 | 845±17 | 660±18 | 0.78 | ||||
| ET-1 (100 nM) | 54±2.7 | 64±1.5 | 0.84 | 940±22 | 586±46 | 0.62* (P<0.01) | ||||
| Isoproterenol (100 nM) | 61±1.8 | 74±4 | 0.82 | 1275±27 | 541±13 | 0.42* (P<0.01) | ||||
| Digoxin (10 μM) | 67±3.5 | 76±3.1 | 0.88 | 834±13 | 675±20 | 0.81 | ||||
| . | Time to reach amplitude peak . | . | . | Time of decay . | . | . | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| . | t0 (milliseconds) . | t1440 (milliseconds) . | t1440:t0 ratio . | t0 (milliseconds) . | t1440 (milliseconds) . | t1440:t0 ratio . | ||||
| Control | 54±2.1 | 68±2.9 | 0.79 | 845±17 | 660±18 | 0.78 | ||||
| ET-1 (100 nM) | 54±2.7 | 64±1.5 | 0.84 | 940±22 | 586±46 | 0.62* (P<0.01) | ||||
| Isoproterenol (100 nM) | 61±1.8 | 74±4 | 0.82 | 1275±27 | 541±13 | 0.42* (P<0.01) | ||||
| Digoxin (10 μM) | 67±3.5 | 76±3.1 | 0.88 | 834±13 | 675±20 | 0.81 | ||||
The table shows the average (mean ± s.e.m.) increase and recovery times for field-stimulation-evoked Ca2+ transients in cells superfused with the reagents shown. The data were sampled either before agonist addition (t0) or after 24 minutes of pacing with the appropriate reagent (t1440). The time to reach peak amplitude was calculated as the interval between depolarisation of the cell and the maximum increase of the Ca2+ transient. The time of decay was taken as the period between the peak Ca2+ rise and the time taken to for cytosolic Ca2+ to return to the pre-depolarisation diastolic level. The data were calculated from ten field-stimulation-evoked Ca2+ transients from 6 myocytes for each condition (i.e. n=60 for each data point)