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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 3, May/June 2015

136

AFRICA

rates of the rats in each group in each time period. The changes

in the heart rates in the amitriptyline-treated groups (groups 1, 2

and 3) and the control group are shown in Fig. 1.

The baseline QRS durations were similar among groups.

The changes in the QRS durations in the groups that did not

received amitriptyline (groups 4, 5 and 6) were non-significant,

whereas the amitriptyline-administered groups (groups 1, 2 and

3) showed a statistically significant increase in the QRS duration.

This increase was more marked in group 1. The increase in QRS

duration was limited in the groups that received amitriptyline

with HS or NaHCO

3

(groups 2 and 3). There was no statistically

significant difference between these groups in terms of increase

in the duration of the QRS. A comparison of the QRS duration

in each group in each time period is shown in Table 3, and a

comparison of the change in QRS duration of the amitriptyline-

treated groups (groups 1, 2 and 3) and control group is shown

in Fig. 2.

The baseline QTc durations were similar among the groups.

There was no significant change in the QTc durations in the

groups that did not receive amitriptyline (groups 4, 5 and 6).

The QTc duration increased in the amitriptyline-treated groups

(groups 1, 2 and 3), but the increase was more marked in group

1. The increase in the QTc duration was reduced in the groups

administered HS or NaHCO

3

with amitriptyline. There was no

statistically significant difference between the two groups (groups

2 and 3) in terms of QTc prolongation. A comparison of the QTc

duration of the groups in each time period is shown in Table 4,

and a comparison of the change in duration of the QTc in the

amitriptyline-treated groups and the control group is shown in

Fig. 3.

Serum samples for sodium and ionised calcium analyses

were taken from the surviving rats at the 60th minute and from

the non-survivors immediately after death. In the groups that

received amitriptyline (groups 1, 2 and 3), the serum sodium

levels had decreased. This decline was most evident in group

1, which did not receive any sodium-containing treatment.

Hyponatraemia was more pronounced in group 2 than group 3.

No subject developed hypernatraemia.

The serum ionised calcium levels were higher in the groups

that received amitriptyline and highest in the amitriptyline-only

group (group 1). The distribution of the serum levels of ionised

calcium and sodium in the groups is shown in Table 5. The serum

sodium levels showed a strong positive correlation with heart

rates, a strong negative correlation with QRS duration, and a

Table 3. QRS changes with time according to group

Group

Start

5th minute

10th minute

15th minute

20th minute

25th minute

1

0.210

±

0.001

*

0.0303

±

0.0015

c,e

0.042

±

0.01

a,c,d,e

0.057

±

0.014

a,b,c,d,e

0.061

±

0.130

a,b,c,d,e

0.072

±

0.02

a,b,c,d,e

2

0.208

±

0.001

*

0.022

±

0.010

*

0.027

±

0.006

a

0.030

±

0.005

a

0.032

±

0.006

a,g,i

0.032

±

0.006

a,i

3

0.208

±

0.003

*

0.022

±

0.002

*

0.034

±

0.008

j,k,l

0.038

±

0.008

b,k,l

0.037

±

0.008

b,j,k,

l

0.038

±

0.009

b,j,k,l

4

0.198

±

0.001

*

0.0190

±

0.001

c

0.020

±

0.001

c,j

0.020

±

0.001

c

0.019

±

0.001

c,g,j

0.020

±

0.001

c,j

5

0.202

±

0.001

*

0.020

±

0.001

*

0.020

±

0.002

d,k

0.020

±

0.01

d

0.021

±

0.001

d,k

0.020

±

0.001

d,k

6

0.195

±

0.003

*

0.0183

±

0.02

e

0.018

±

0.001

e,l

0.019

±

0.002

e,k,l

0.019

±

0.001

e,i,l

0.019

±

0.001

e,i,l

Mean

0.204

±

0.002

0.022

±

0.007

0.027

±

0.01

0.030

±

0.015

0.031

±

0.016

0.031

±

0.018

p

-value

0.782

0.032

0.000

0.000

0.000

0.001

*

The group with no difference from the others,

p

<

0.05 (

a

compared with groups 1 and 2,

b

compared with groups 1 and 3,

c

compared with groups 1 and 4,

d

compared

with groups 1 and 5,

e

compared with groups 1 and 6,

f

compared with groups 2 and 3,

g

compared with groups 2 and 4,

h

compared with groups 2 and 5,

i

compared with

groups 2 and 6,

j

compared with groups 3 and 4,

k

compared with groups 3 and 5,

l

compared with groups 3 and 6).

400

350

300

250

200

150

100

50

0

0 5 10 15 20 25 30 35 40 45 50 55 60

Duration (minutes)

Heart rate (beats/minute)

Only amitriptyline

Amitriptyline +

hypertonic saline

Amitriptyline +

sodium bicarbonate

Control

Fig. 1.

Heart rate changes of the amitriptyline-administered

groups and control group with time.

0.080

0.070

0.060

0.050

0.040

0.030

0.020

0.010

0.000

0 5 10 15 20 25 30 35 40 45 50 55 60

Duration (minutes)

QRS interval (seconds)

Only amitriptyline

Amitriptyline +

hypertonic saline

Amitriptyline +

sodium bicarbonate

Control

Fig. 2.

QRS changes of the amitriptyline-administered groups

and control group with time.