(i) Efficacy of ligands for benzodiazepine binding sites (before
infusion of chloroquine)
Twenty-seven rats entered in the study, but 3 died immediately following
the administration of clonazepam and were excluded. There were no
differences between pre- and 10 minutes post-drug haemodynamics or ECG
parameters or between randomised groups with the administration of
diazepam, clonazepam, Ro5-4864 or vehicle. In the presence of these
agents, chloroquine reduced blood pressure, heart rate and contractility
index; and increased the PR, QRS and QTc intervals (Table 3). There were
no significant differences in these parameters, or in the time to
developing cardiac arrhythmias: 18.1 ± 2.8, 15.8 ± 1.6, 17.5 ± 1.2, 17.8
± 2.3 minutes, between the control, diazepam, clonazepam and Ro5-4864
groups, respectively.