(vi) Efficacy of diazepam and adrenaline (during infusion of
chloroquine)
Twenty-seven rats was included, but 3 died before the end of the
experiment – one from each of the control, diazepam, and diazepam +
adrenaline groups. During the first 30 minutes of infusion, chloroquine
caused significant changes in all parameters, with the exception of the
QRS and QTc intervals in the adrenaline group. The lack of an effect
with diazepam (2 mg kg-1) alone was consistent with
trial (ii). The effects of adrenaline alone did not deviate
significantly from the control group in any parameter other than the QRS
interval, but this was not prolonged following chloroquine (Figure 2).
The combined administration of diazepam and adrenaline resulted in an
improvement of cardiac contractility compared to the control and
diazepam groups but not the adrenaline group (84 ± 3 versus 78 ± 8
s-1; p=0.063). No significant differences were
observed in the other parameters (Table 3).
Pre-chloroquine potassium concentrations were in the range expected for
rats (Burns and De Lannoy, 1966). Chloroquine alone did not cause any
significant changes in arterial PO2,
PCO2 or pH values over a period of 30 minutes infusion.
The combined administration of diazepam and adrenaline, however, reduced
PO2 when compared to pre-intervention values but not
when compared to the other groups. Chloroquine did not alter electrolyte
concentrations; but intervention groups containing adrenaline were more
hypokalaemic than the diazepam and control groups (Table 4).