全 文 ：Effect of dehydrocorydaline on isolated thoracic aorta in rats
FU Yan-Jun＊ , YOU Chun-Lai , ZHANG Xiao-Yu , WANG Hui
(Department of Pharmacology , Liaoning College of Traditional Chinese Medicine , Shenyang　110032 , China)
Abstract:The relaxant effect and its mechanism of dehy-
drocorydaline(DHC)was studied on the isolated thoracic
aorta rings in rats.DHC showed relaxant effects on tho-
racic aorta with intact or without endothelium.The con-
traction responses induced by norepinephrine(NE), KCl ,
and Ca2+was antagonized by 12.5 to 200μmol·L-1DHC
in a non-competitive manner.The pD′2 values were
5.12 , 3.83 , 3.49 , respectively.In Ca2+-free modified
Krebs solution , the contraction of two components induced
by NE were inhibited significantly by 25μmol·L-1 DHC.
The effect features of DHC mentioned above were just like
that of verapamil in the same experimental conditions.
The results suggest that the relaxant effect of DHC on
rat′s thoracic aorta be not dependent on endothelium , and
be closely related to the blockage of Ca2+ entry through
both potential-dependent calcium channel and receptor-
operating calcium channel , and to the inhibition of intra-
cellular Ca2+ release.
Key words:calcium channel blockers;dehydrocory-
daline;verapamil;thoracic , aorta;vasodilation
CLC number:R972
Document code:A
Article ID:1000-3002(2001)05-0326-04
Dehydrocorydaline(DHC) is an alkaloid
extracted from Corydalis yanhusou W.T.Wang.
It had been reported that DHC could protect
myocardium from reperfusion injury , improve the
volume of blood flow in coronary venous sinus and
reduce the oxygen consumption of myocardium[ 1] ;
and DHC could relax rat′s trachea , stomach , etc.,
and the actions may be related to the blockage of
calcium channel
[ 2] .But the action of DHC on rat′s
thoracic aorta has not been reported.This study
was taken to observe and compare the effects of
DHC on contractions induced by norepinephrine
　
　　Received date:2000-12-04　Accepted date:2001-04-25
　　Biography:FU Yan-Jun(1966-), female , native of Shenyang ,
Liaoning Province , lecturer , medical master degree , main research
field is pharmacology and toxicology.
　　＊Corresponding author.Tel:(024)88433062
(NE), KCl and CaCl2 on rat′s thoracic aorta with
that of verapamil(Ver)as a representative calci-
um-channel blocker , and to compare the inhibitory
action of DHC on the two contractive components
evoked by NE with that of Ver.
1　MATERIALS AND METHODS
1.1　Reagents
DHC(purity 95%)was provided by Tianjin
Medical and Pharmaceutical Institute and dissolved
in normal saline and stored at 4℃ within one
week.Ver was a product of Lianyungang Pharma-
ceutical Factory.NE and phenylephrine(Phe)
were products of Shanghai Tianfeng Pharmaceutical
Factory.
Modified Krebs solution (PSS)[ 3] contains
(mmol·L-1)NaCl 112.0 , KCl 5.0 , MgSO4 1.2 ,
KH2PO4 1.0 , NaHCO3 25 , CaCl2 2.5 , and glucose
11.5.The components of Ca2+-free PSS[ 3] was
similar to those of PSS but edetic acid 0.1 mmol·
L
-1
was added instead of CaCl2.High K+ , Ca2+-
free-PSS[ 3] was consisted of(mmol·L-1)NaCl 17 ,
KCl 100 , and other components were similar to
those of Ca2+-free PSS.Ver , NE and Phe were
dissolved in PSS respectively before used.
1.2　Isolated thoracic aorta preparation
Sprague-Dawley rats(♀, ♂, 250-350 g)
were provided by the Animal Center of China Med-
ical University.Rats were sacrificed by stunning
and decapitation.The thoracic aorta was immedi-
ately removed and placed in 0℃PSS , removed fat
and connective tissues and cut into rings about 3-
4 mm long[ 4] .The endothelium of rings was re-
moved by rubbing against a syringe needle , and
the denuded rings were tested without response to
acetylcholine
[ 5] .The aortic rings were placed in
bath-tubes containing 10 mL PSS saturated with
·326· Chinese Journal of Pharmacology and Toxicology　2001　Oct;15(5):326-329
95%O2+5%CO2.Under a resting tension of 2
g , isometric tension was measured with a force
transducer and recorded with XWT-204 recorder.
The preparations in bath-tube were allowed to
equilibrate for 1.5-2.0 h before experiment.
1.3　Contraction induced by norepinephrine
or KCl in PSS
[ 3 , 6]
After the preparations equilibrated , NE 8.85
pmol·L-1 -8.903 nmol·L-1 or KCl 10.5-
68.78 mmol·L-1 were accumulatively added to
the bath-tubes respectively to obtain the normal
concentration-effect curves of NE or KCl.Then
the preparations were washed to normal tension
and bathed in PSS for 30 min.Then DHC or Ver
was added.Ten minutes later , concentration-ef-
fect curves of NE or KCl were performed in the
presence of DHC or Ver.
1.4 　Contraction induced by CaCl2 in high
K+ , Ca2+-free-PSS
After the preparations equilibrated , the prepa-
rations were washed with Ca2+-free-PSS and bathed
in it for 30 min , and then equilibrated in high K+ ,
Ca
2+-free-PSS for 15 min again , CaCl2was added
accumulatively from 0.145 to 1.25 mmol·L-1 to
observe the normal concentration-effect curve.Af-
ter that , DHC or Ver was added and bathed for 10
min , and then the concentration-effect curve of
CaCl2 was performed in the presence of DHC or
Ver.
1.5　Contraction of two components induced
by norepinephrine in Ca
2+-free-PSS
After the preparations equilibrated in PSS ,
NE 1 nmol·L-1 was added and the normal con-
tractility was recorded.The preparations were
bathed in Ca
2+-free-PSS , 30 min later , NE 1
nmol·L-1 was added , when the initial fast con-
traction reached peak(induced by intracellular
Ca
2+
release), CaCl2 2.5 mmol·L-1 was given
rapidly , and the sustained contraction(evoked by
extracellular Ca2+ influx) was recorded.The
preparations were washed and bathed to equilibri-
um in Ca2+-free-PSS again.Ver or DHC was
added 10 min before NE and Ca2+ were added in
the presence of DHC or Ver.
1.6　Statistical analysis
Results were expressed as x±s.The signif-
icance of difference between groups was checked
by t test.The determination of pD′2was according
to Quantitative Pharmacology
[ 7] .
2　RESULTS
2.1　Effect of dehydrocorydaline on phenyl-
ephrine-evoked contraction of aorta rings with
or without endothelium
DHC 1 , 3 , 10 , 30 , 100 and 300μmol·L-1
was added cumulatively to the preparations with or
without endothelium.The inhibitory effect of DHC
on the contraction evoked by 1μmol·L-1 Phe was
not significantly different between with and without
endothelium rings(n=7 , P>0.05).
2.2 　Effects of dehydrocorydaline or vera-
pamil on contractions evoked by norepi-
nephrine , KCl or CaCl2
DHC produced a concentration-dependent in-
hibition on contractions induced by NE , KCl or
CaCl2.The concentration-effect curves moved to
the right , and the maximal contraction was de-
pressed.The feature of actions of DHC was similar
to that of Ver.The pD′2 values of DHC on con-
tractions induced by NE , KCl or CaCl2 were
5.12 , 3.83 , and 3.94 , respectively , while pD′2
values of Ver were 6.17 , 6.83 and 6.56 , respec-
tively(Fig 1).
2.3　Effect of dehydrocorydaline or verapamil
on the contraction of two components induced
by norepinephrine
In Ca2+-free-PSS , the initial fast response
induced by NE(intracellular Ca2+ release)and
the sustained contraction evoked by extracellular
Ca
2+
influx were inhibited significantly by 25
μmol·L-1 DHC or Ver(Tab 1).
3　DISCUSSION
The results showed DHC non-competitively
inhibited the contraction induced by NE , KCl or
CaCl2 , just like Ver.It is well known that the
contraction of vascular smooth muscle is initiated
·327·中国药理学与毒理学杂志　　2001 年 10月;15(5)
Fig 1.　Cumulative concentration-response curves for norepinephrine(NE), CaCl2 or KCl in isolated rat tho-
racic aorta in the absence or presence of verapamil(Ver)or dehydrocorydaline(DHC).(★)Control.The maximal re-
sponse induced by NE , CaCl2 or KCl was taken as 100%.A1:(0.75±0.17)g , n =6;B1:(0.76±0.15)g , n =6;A2:(0.73±0.09)g ,
n=5;B2:(0.62±0.15)g , n=6;A3:(0.81±0.39)g , n =6;B3:(0.96±0.10)g , n=5 , respectively.(○, ■, △)A1:Ver 30 ,
100 , 300 nmol·L-1 , n=6;A2 and A3:Ver 3 , 10 , 30 nmol·L-1 , n=5 , 6;B1:DHC 12.5 , 25 , 50 μmol·L-1 , n=6.B2:DHC 50 ,
100 , 200 μmol·L-1 , n=6;B3:DHC 25 , 50 , 100μmol·L-1 , n=5.Ver or DHC was added 10 min before NE , CaCl2 or KCl. x±s.
Tab 1.　Effect of dehydrocorydaline or verapamil on
the contraction of two components induced by norepi-
nephrine(1 nmol·L-1)in rat thoracic aortic rings
Drug
/μmol·L-1
Contraction/mg
Without CaCl2 With CaCl2
Control 　　　311±40 　　　652±106
Ver 25 92±34＊＊ 252±75＊＊
Control 274±97 615±59
DHC 25 86±22＊＊ 331±50＊＊
Ver or DHC was added 10 min before NE. x±s , n=6.＊＊P <
0.01 , compared with corresponding control group.
by an increase in intracellular calcium level.This
may be achieved by two ways:extracellular Ca2+
influx from potential depending calcium channel
(PDC)evoked by depolarization with high potas-
sium concentration or from receptor-operating cal-
cium channel(ROC)evoked by NE and release of
intracellular Ca2+[ 8, 9] .Thus the results suggest
DHC block both PDC and ROC.
The comparison of the values of pD′2 showed
that Ver inhibited the increase in intracellular
Ca
2+
induced by both high K
+
or NE more po-
tently than DHC.But the inhibitory features of
Ver was not complete as the same as that of DHC.
Ver was more potent for inhibiting PDC , while
DHC was more effective for blocking ROC.The
results suggest that DHC block not only extracel-
lular Ca2+ influx but also intracellular Ca2+ re-
lease.The result of Ver was in agreement with
that of Polster et al[ 3] .
The results showed that DHC and Ver inhib-
ited the contraction of two components evoked by
NE.The result of Ver was in consist with that of
Dong et al[ 10] reported.The result of DHC in-
hibiting contraction in both with or without en-
dothelium rings suggests the relaxant effect of
DHC in rat thoracic aorta rings be not dependent
on endothelial cells.
Acknowledgement　We thank professor WANG Ding
(Tianjing Medical and Pharmaceutical Institute)for the
gift of dehydrocorydaline.We thank technician Li Yun-
Xing for his technical assistance.
4　REFERENCES:
[ 1] 　Jing XR , Wu QR, Shi HL , Chen WP , Chang SQ , Zhao
·328· Chinese Journal of Pharmacology and Toxicology　2001　Oct;15(5)
SY, et al .Pharmacological actions of dehydrocorydaline on
cardiovascular system[ J] .Acta Pharm Sin , 1982 , 17(1):
61-64.(in Chinese)
[ 2] 　Zhao HW , Zhao XM , Zhang XY.Comparison of relaxant
effects of dehydrocorydaline on isolated rat smooth muscles
[ J] .Acta Pharmacol Sin , 1998 , 19(2):190.
[ 3] 　Polster P , Christophe B , van Damne M , Houlliche A ,
Chatelain P.SR 33557 , a novel calcium entry blocker.
I.In vitro isolated tissue studies[ J] .J Pharmacol Exp
Ther , 1990 , 255(2):593-599.
[ 4] 　Yao W , Zhu QY , Su DF.Effects of tetrandrine and nefer-
ine on the phenylephrine-induced contractions in rat aortic
rings[ J] .Acta Pharm Sin , 1991 , 7(5):357-359.(in
Chinese)
[ 5] 　Furchgott RF , Zawadzki JV.The obligatory role of endothe-
lial cells in the relaxation of arterial smooth muscle by
acetylcholine[ J] .Nature , 1980 , 288(5789):373-376.
[ 6] 　Kwan CY, Deng HW , Guan YY.Tetrandrine is not a se-
lective calcium channel blocker in vascular smooth muscle
[ J] .Acta Pharmacol Sin , 1992 , 13(5):385-390.
[ 7] 　Sun RY.Determination of pD′2[ A] .In:Sun RY.Quanti-
tative Pharmacology [ M] .Beijing:The People′s Medical
Publishing House , 1987.446-448.(in Chinese)
[ 8] 　Broekaert A , Godfraind T.A comparison of the inhibitory
effect of cinnarizine and papaverine on the noradrenaline-
and calcium-evoked contraction of isolated rabbit aorta and
mesenteric arteries[ J] . Eur J Pharmacol , 1979 , 53:
281-288.
[ 9] 　Saida K , van Breemen C.Mechanism of Ca2+ antagonist-
induced vasodilation.Intracellular actions[ J] .Circ Res ,
1983 , 52(2):137-142.
[ 10] 　Dong H , Yang ZC , Wei X.Effect of nimodipine on the
contraction and the Ca influx of rat aorta[ J] .Acta Pharma-
col Sin , 1990 , 11(4):304-307.(in Chinese)
去氢紫堇碱对大鼠离体胸主动脉平滑肌的作用
付彦君 , 尤春来 , 张效禹 , 王　卉
(辽宁中医学院中药系药理学教研室 , 辽宁 沈阳　110032)
摘要:去氢紫堇碱(DHC)12.5 ～ 200 μmol·L-1对大鼠
离体胸主动脉环由去甲肾上腺素(NE), KCl , CaCl2
诱发的收缩反应均呈非竞争性拮抗作用 , pD′2 分别
为5.12 , 3.83和 3.49 , 且 DHC 的该松弛作用与血
管内皮细胞无关.DHC对 NE诱发的血管平滑肌两
种成分的收缩均呈显著抑制作用 ,与经典钙拮抗剂
维拉帕米相似.结果提示 DHC 对血管平滑肌的松
弛作用与外钙内流及内钙释放均密切相关.
关键词:钙通道阻滞药;去氢紫堇碱;维拉帕米;主
动脉 , 胸;血管舒张
(本文编辑　董立春)
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