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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 2, March/April 2019
AFRICA
79
Change in late sodium current of atrial myocytes in
spontaneously hypertensive rats with allocryptopine
treatment
Ying Dong, Yun Huang, Hong-lin Wu, Jun Ke, Yuan-li Yin, Chao Zhu, Bin Li, Jie Li, Lei Gao, Qiao Xue,
Jian-cheng Zhang, Yang Li
Abstract
Aim:
We aimed to study the effect of allocryptopine (All) on
the late sodium current (I
Na,Late
) of atrial myocytes in spontane-
ously hypertensive rats (SHR).
Methods:
The enzyme digestion method was used to separate
single atrial myocytes from SHR and Wistar–Kyoto (WKY)
rats. I
Na,Late
was recorded using the patch-clamp technique, and
the effect of All was evaluated on the current.
Results:
Compared with WKY rat cells, an increase in the
I
Na,Late
current in SHR myocytes was found. After treat-
ment with 30
μ
M All, the current densities were markedly
decreased; the ratio of I
Na,Late
/I
Na,peak
of SHR was reduced by
30
μ
M All. All reduced I
Na,Late
by alleviating inactivation of
the channel and increasing the window current of the sodium
channel. Furthermore, I
Na,Late
densities of three SCN5A muta-
tions declined substantially with 30
μ
M All in a concentra-
tion-dependent manner.
Conclusion:
The results clearly show that an increase in I
Na,Late
in SHR atrial myocytes was inhibited by All derived from
Chinese herbal medicine.
Keywords:
allocryptopine, spontaneously hypertensive rats, atrial
myocytes, late sodium current
Submitted 19/8/18, accepted 26/11/18
Published online 14/3/19
Cardiovasc J Afr
2019;
30
: 79–86
www.cvja.co.zaDOI: 10.5830/CVJA-2018-072
Atrial fibrillation (AF) is the most common arrhythmia and
contributes substantially to cardiac morbidity and mortality.
Many clinical studies have suggested that AF is associated with
risk factors such as hypertension, aging and diabetes mellitus.
Hypertension is a major risk factor for AF.
1
The heart of the spontaneously hypertensive rat (SHR) has
demonstrated inducible and even spontaneously occurring AF.
2-4
A main cause of AF is electrical remodelling with a longer
action potential duration (APD) and atrial refractory period.
5
This electrical remodelling has been associated with changes in
various ion currents, including an increase in the late sodium
current (I
Na,Late
).
6,7
Allocryptopine (All) is an alkaloid extracted from
Corydalis
decumbens
(Thunb.) Pers. Papaveraceae. Our prior studies have
shown that All has potential anti-arrhythmic action in animal
models, indicating that All can inhibit arrhythmias induced
by aconitine with abnormal sodium currents.
8,9
Interestingly,
an increase in I
Na,Late
of the SCN5A-T353I mutation, as a gene
to code Nav1.5 channel protein, has been found to be greatly
inhibited by All.
10
Our study focused on investigating a change
in I
Na,Late
in SHR atrial myocytes and the effect of All on I
Na,Late
.
Methods
Male SHR (six to eight months of age and a weight of
180–200 g) were purchased from the Experimental Animal
Centre of the Chinese PLA General Hospital. Age- and gender-
matched normotensive Wistar–Kyoto rats (WKY) served as
controls. Research was carried out in accordance with the Guide
for the Care and Use of Laboratory Animals, issued by the
National Committee of Science and Technology of China.
All animals were kept in a laboratory and adapted for a
week. Heart rate and blood pressure in conscious animals were
measured using the tail-cuff method (CODA system, Kent
Scientific, USA).
Solutions were made up as follows:
•
Tyrode’s solution (mM): KCl 5.4, NaCl 136, MgCl
2
1.0,
NaH
2
PO
4
0.33, CaCl
2
1.8, HEPES 10 and glucose 10 (pH 7.4).
•
Kreb’s buffer solution (mM): KCl 40, KOH 80, KH
2
PO
4
25,
MgSO
4
3.0, L-glutamine 50, taurine 20, HEPES 10 glucose
10, and EGTA 0.5 (pH 7.4).
•
For AP recording, the internal pipette solution contained
(mM) NaCl 10, CaCl
2
1, MgATP 5, KCl 120, EGTA 11, and
HEPES 10 (pH 7.4). The bath solution was Tyrode’s solution.
•
For I
Na,Late
recording, the bath solution contained (mM) NaCl
130, CaCl
2
2, MgCl
2
1.2, CsCl 5, glucose 5 and HEPES 10 (7.4).
•
For I
Na,Late
recording, the internal pipette solution contained
(mM) cesium aspartate 80, CsCl 60, EGTA 11, HEPES 10
and Na
2
ATP 5 (pH 7.2).
Department of Cardiology, Chinese PLA General Hospital,
Beijing 100853, China
Ying Dong, PhD
Hong-lin Wu, MSc
Yuan-li Yin, MSc
Chao Zhu, PhD
Bin Li, MSc
Jie Li, PhD
Lei Gao, PhD
Qiao Xue, PhD
Yang Li, PhD,
liyang301pla@163.comDepartment of Gerontology, Union Hospital, Tongji Medical
College, Huazhong University of Science and Technology,
430022, Wuhan, China
Yun Huang, PhD
Provincial Clinical Medicine College of Fujian Medical
University, Fuzhou 350001, Fujian, China
Jun Ke, PhD
Jian-cheng Zhang, PhD,
13696860345@126.com