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Predominant Negative Inotropic Effect of UTP on Dog Cardiac Muscle
Short Communications
Predominant
Negative on
Dog
Japan. J. Pharmacol. 35, 334 (1984)
Inotropic
Cardiac
Effect
of UTP
Muscle
Shigetoshi CHIBA, Miyoharu KOBAYASHI, Masahiro SHIMOTORI and Yasuyuki FURUKAWA Departmentof Pharmacologyand Research Laboratoryfor CardiovascularDiseases, Shinshu UniversitySchoolof Medicine,Matsumoto390, Japan AcceptedApril27, 1984 It is reported that uridine triphosphate (UTP) gives rise to a monotonic increase in the force of contraction (1, 2). Singh and Flitney (3) reported that UTP produced a long-lasting increase in isometric tension on the isolated frog ventricle and that the increase was unaffected by adrenergic receptor antagonists such as propranolol and phentolamine. In mammalian hearts, James (4) reported that UTP had no chronotropic effect on direct perfusion of the SA node of the dog in situ. In the present study, we made an attempt to investigate the effect of UTP on dog atrial and ventricular muscle preparations perfused with donor's blood, the method of the perfusion being developed by Chiba et al. (5) and Chiba (6). Eleven isolated right atrial and 5 left ventricular preparations were used to examine the inotropic and chronotropic effect of UTP. The preparation was perfused with heparinized arterial blood introduced from the donor dog anesthetized with 30 mg/kg i.v. of sodium pentobarbital; the right atrium was perfused through a cannula inserted into the sinus node artery and the left ventricle was perfused through a cannula inserted into the anterior descending branch of the left coronary artery. The details of the preparation are described in previous papers (5, 6). The isometric tension development and atrial rate were continuously measured during the experiments. The ventricular preparations were electrically paced at 2-2.5 Hz, 1 msec duration and suprathreshold voltage. Drugs used were uridine 5'-triphosphate trisodium (UTP, Sigma), acetylcholine chloride (Daiichi), norepinephrine hydrochloride (Sankyo), propranolol hydrochloride (Sumi-
tomo
Chemicals)
(Takeda). 0.03
ml)
artery
of
of
was the
anterior left
and
Each
the
atropine
drug
injected canine
into
the
isolated
descending
sulfate
solutions
(0.01sinus
atrium
branch
node
or
of
into
the
the
isolated
ventricle. When
sinus
UTP node
was
artery
chronotropic
administered
of
and
the
inotropic
relatedly
induced
in
300 ƒÊg.
UTP
induced
chronotropic effect. effects
UTP
caused
followed the
by
a
negative
nant.
Summarized
2(A).
The
from
inotropic
inotropic
effect data
blocked inotropic
not
influenced
inhibited,
although
by blocked
choline
in
When UTP
UTP
The
this
of
UTP
atropine,
were which
chronotropic
0.1 ƒÊg
of
injected
into
initial
profound
an
followed
inotropic Summarized
a previous In
was
effect
positive 1(B).
chronotropic
negative of
of
acetyl-
2 experiments.
induced
inotropic
effects
1 mg
,ƒÊg of
the
of inonot
completely
negative
effects
7).
and were
were
10
Fig. cited
10 ƒÊg
chronotropic mg of UTP
norepinephrine
in are
(5,
positive of 1
inotropic
2(B).
with
to
one, predomi-
UTP
papers
The
slight
tracing of UTP.
shown for
published
responses
completely and
that
to
effect
being
treatment
(n=3).
and
a a
inotropic
are
except
10
negative by
negative positive
dose-
of
slight
followed
slight
significantly of
were
a
after
0.01 ƒÊg
a
the
biphasic
range
shows doses
previously
propranolol, tropic effects
dose
Figure 1(A) of increasing
data
Even
atrium, effects
a
effect
positive of the
into
right
data paper study,
effect data of
by as are
adenosine
the
ventricle, negative
a
secondary
shown shown are
in in cited
Fig. Fig. from
(8). we
demonstrated
that
UTP
Short Communications
Japan. J. Pharmacol. 35, 335 (1984)
(A)
(B)
Fig. 1. (A) Chronotropic and inotropic responses to increasing doses of UTP in an isolated and bloodperfused canine atrial preparation. (B) inotropic response to increasing doses of UTP in an isolated and perfused left ventricular preparation of the dog. The ventricular muscle was electrically paced at 2 Hz, 1 msec duration and 5 volts.
produced the predominant negative inotropic effect in both atrial and ventricular muscles accompanying slight changes in SA nodal pacemaker activity. Previously, it was shown that adenosine induced negative chronotropic and negative inotropic effects in a dose-related manner in isolated and bloodperfused atrial preparations (6). Comparing to previous results, the UTP-induced negative inotropic effect was approximately 10 times less potent than the adenosine-induced negative inotropic one, but the UTP-induced negative chronotropic effect was not significant even at the large dose of 3 mg, this result being apparently different from that in the adenosine experiments in dog atria. In the ventricle, UTP also induced the biphasic inotropic effect. The UTP-induced positive inotropic effect in the ventricle was greater than that in atria, but the UTPinduced negative inotropic effect was similar
to that in atria. As shown in Fig. 2, adenosine induced a biphasic inotropic effect as reported previously in the same ventricular preparations (8), but UTP caused the negative inotropic effect predominantly. It is reported that purine nucleosides and nucleotides can alter the physiological functions of many different cells. Burnstock (9) has postulated that there are specific membrane receptors which mediate such responses and subdivides these so-called purinergic receptors into two types, based on the relative order of potencies of their agonists and antagonists, namely P-1 and P-2 receptors. According to Burnstock (10), adenosine exerts its action via P-1 receptors. It is necessary to analyze pharmacologically whether the UTP-induced chronotropic and inotropic effects are mediated via any kind of purinergic receptors or not. It was already reported that UTP-induced
Short Communications
Japan. J. Pharmacol. 35, 336 (1984)
(A)
Fig.
2.
UTP tension above in
11
(B)
(A)
in
Chronotropic
isolated
dog
development, each
point.
canine
present
the
Each
and
vertical
Control
preparations.
paced
and atria.
(B) ventricles.
S.E.M.
inotropic
sinus Inotropic Each
Control
tension
effects
point bars rate
ncreasing the
represent before
effects point
of
represents
the
UTP of
developed
of
S.E.M.;
the was
chronotropic changes were not significant in the dog heart (4). In this study, we confirmed that UTP does not have any significant chronotropic effect, and we demonstrated that UTP induces a negative inotropic effect, which is not mediated via cholinergic mechanisms. Singh and Flitney (3) showed that UTP produced only a positive inotropic effect on the isolated frog ventricle when superfused, which was unaffected by adrenergic receptor antagonists. In the frog ventricle, UTP did not produce the negative inotropic effect, but in the dog atrium and ventricle, we demonstrated the negative inotropic effect of UTP. The reason for the difference in the results is not readily apparent, but may be due to a species difference or to differences in experimental conditions. It is concluded that UTP induces both negative and positive chronotropic effects and
of
of
mean
of
1.5•}0.3
g
changes
number
was
doses
norepinephrine,
maximum the
administration
increasing
represents
doses
mean
of
95•}3.8
adenosine
maximum (mean•}S.E.M.)
adenosine in
sinus
observations beats/min
and
UTP
changes,
is
and
in
indicated
(mean•}S.E.M.) in and
in
and
rate
the
isolated
vertical
and bars
re-
5 preparations.
also has inotropic effects, the predominant effect, however, being the negative inotropic effect. Acknowledgment: This study was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education. Science and Culture of Japan (Grant No. 58570089). References 1 Versprill, A.: The influence of uridine nucleotides upon the isolated frog heart. Pfluegers Arch. Ges. Physiol. 277, 285-292 (1963) 2 Flitney, F.W. and Singh, J.: Exogenous uridine 5'-triphosphate (UTP) enhances conctractility and stimulated 3`,5'-cyclic nucleotide metabolism in the frog ventricle. J. Physiol. (Lond.) 291, 52P-53P (1979) 3 Singh, J. and Flitney, F.W.: Effects of uridine triphosphate on contractility, cyclic nucleotide levels and membrane potential in the isolated frog ventricle. Pfluegers Arch. Ges. Physiol.
Short Communications
392, 1-6 (1981) 4 James, T.N.: The chronotropic action of ATP and related compounds studied by direct perfusion of the sinus node. J. Pharmacol. Exp. Ther. 149, 233-247 (1965) 5 Chiba, S., Kimura, T. and Hashimoto, K.: Muscarinic suppression of the nicotinic action of acetylcholine on the isolated, blood-perfused atrium of the dog. Arch. Pharmacol. 289, 31 5325 (1975) 6 Chiba, S.: Effect of pentobarbital, verapamil and manganese on the frequency-force relationship of the isolated atrium and ventricle of the dog heart. Eur. J. Pharmacol. 40, 225-232 (1976) 7 Chiba, S.: Differences in chronotropic and inotropic responses of canine atrial muscle and
Japan. J. Pharmacol. 35, 337 (1984)
SA node pacemaker activity to adenosine and ACh. Japan. Heart J. 17,73-79 (1976) 8 Chiba, S,, Watanabe, H. and Furukawa, Y.: Inotropic responses of isolated atrial and ventricular muscle from the dog heart to inosine, guanosine and adenosine. Clin. Exp. Pharmacol. Physiol. 8, 171-174 (1981) 9 Burnstock, G.: A basis for distinguishing two types of purinergic receptors. In Cell Membrane Receptor for Drugs and Hormones: A Multidisciplinary Approach, Edited by Straub. R.N. and Bolis, L., p. 107-117, Raven Press, New York (1978) 10 Burnstock, G.: Purinergic receptors in the heart. Circ. Res. 46, Supp. 1, 175-182 (1980)
Predominant
Negative on
Dog
Japan. J. Pharmacol. 35, 334 (1984)
Inotropic
Cardiac
Effect
of UTP
Muscle
Shigetoshi CHIBA, Miyoharu KOBAYASHI, Masahiro SHIMOTORI and Yasuyuki FURUKAWA Departmentof Pharmacologyand Research Laboratoryfor CardiovascularDiseases, Shinshu UniversitySchoolof Medicine,Matsumoto390, Japan AcceptedApril27, 1984 It is reported that uridine triphosphate (UTP) gives rise to a monotonic increase in the force of contraction (1, 2). Singh and Flitney (3) reported that UTP produced a long-lasting increase in isometric tension on the isolated frog ventricle and that the increase was unaffected by adrenergic receptor antagonists such as propranolol and phentolamine. In mammalian hearts, James (4) reported that UTP had no chronotropic effect on direct perfusion of the SA node of the dog in situ. In the present study, we made an attempt to investigate the effect of UTP on dog atrial and ventricular muscle preparations perfused with donor's blood, the method of the perfusion being developed by Chiba et al. (5) and Chiba (6). Eleven isolated right atrial and 5 left ventricular preparations were used to examine the inotropic and chronotropic effect of UTP. The preparation was perfused with heparinized arterial blood introduced from the donor dog anesthetized with 30 mg/kg i.v. of sodium pentobarbital; the right atrium was perfused through a cannula inserted into the sinus node artery and the left ventricle was perfused through a cannula inserted into the anterior descending branch of the left coronary artery. The details of the preparation are described in previous papers (5, 6). The isometric tension development and atrial rate were continuously measured during the experiments. The ventricular preparations were electrically paced at 2-2.5 Hz, 1 msec duration and suprathreshold voltage. Drugs used were uridine 5'-triphosphate trisodium (UTP, Sigma), acetylcholine chloride (Daiichi), norepinephrine hydrochloride (Sankyo), propranolol hydrochloride (Sumi-
tomo
Chemicals)
(Takeda). 0.03
ml)
artery
of
of
was the
anterior left
and
Each
the
atropine
drug
injected canine
into
the
isolated
descending
sulfate
solutions
(0.01sinus
atrium
branch
node
or
of
into
the
the
isolated
ventricle. When
sinus
UTP node
was
artery
chronotropic
administered
of
and
the
inotropic
relatedly
induced
in
300 ƒÊg.
UTP
induced
chronotropic effect. effects
UTP
caused
followed the
by
a
negative
nant.
Summarized
2(A).
The
from
inotropic
inotropic
effect data
blocked inotropic
not
influenced
inhibited,
although
by blocked
choline
in
When UTP
UTP
The
this
of
UTP
atropine,
were which
chronotropic
0.1 ƒÊg
of
injected
into
initial
profound
an
followed
inotropic Summarized
a previous In
was
effect
positive 1(B).
chronotropic
negative of
of
acetyl-
2 experiments.
induced
inotropic
effects
1 mg
,ƒÊg of
the
of inonot
completely
negative
effects
7).
and were
were
10
Fig. cited
10 ƒÊg
chronotropic mg of UTP
norepinephrine
in are
(5,
positive of 1
inotropic
2(B).
with
to
one, predomi-
UTP
papers
The
slight
tracing of UTP.
shown for
published
responses
completely and
that
to
effect
being
treatment
(n=3).
and
a a
inotropic
are
except
10
negative by
negative positive
dose-
of
slight
followed
slight
significantly of
were
a
after
0.01 ƒÊg
a
the
biphasic
range
shows doses
previously
propranolol, tropic effects
dose
Figure 1(A) of increasing
data
Even
atrium, effects
a
effect
positive of the
into
right
data paper study,
effect data of
by as are
adenosine
the
ventricle, negative
a
secondary
shown shown are
in in cited
Fig. Fig. from
(8). we
demonstrated
that
UTP
Short Communications
Japan. J. Pharmacol. 35, 335 (1984)
(A)
(B)
Fig. 1. (A) Chronotropic and inotropic responses to increasing doses of UTP in an isolated and bloodperfused canine atrial preparation. (B) inotropic response to increasing doses of UTP in an isolated and perfused left ventricular preparation of the dog. The ventricular muscle was electrically paced at 2 Hz, 1 msec duration and 5 volts.
produced the predominant negative inotropic effect in both atrial and ventricular muscles accompanying slight changes in SA nodal pacemaker activity. Previously, it was shown that adenosine induced negative chronotropic and negative inotropic effects in a dose-related manner in isolated and bloodperfused atrial preparations (6). Comparing to previous results, the UTP-induced negative inotropic effect was approximately 10 times less potent than the adenosine-induced negative inotropic one, but the UTP-induced negative chronotropic effect was not significant even at the large dose of 3 mg, this result being apparently different from that in the adenosine experiments in dog atria. In the ventricle, UTP also induced the biphasic inotropic effect. The UTP-induced positive inotropic effect in the ventricle was greater than that in atria, but the UTPinduced negative inotropic effect was similar
to that in atria. As shown in Fig. 2, adenosine induced a biphasic inotropic effect as reported previously in the same ventricular preparations (8), but UTP caused the negative inotropic effect predominantly. It is reported that purine nucleosides and nucleotides can alter the physiological functions of many different cells. Burnstock (9) has postulated that there are specific membrane receptors which mediate such responses and subdivides these so-called purinergic receptors into two types, based on the relative order of potencies of their agonists and antagonists, namely P-1 and P-2 receptors. According to Burnstock (10), adenosine exerts its action via P-1 receptors. It is necessary to analyze pharmacologically whether the UTP-induced chronotropic and inotropic effects are mediated via any kind of purinergic receptors or not. It was already reported that UTP-induced
Short Communications
Japan. J. Pharmacol. 35, 336 (1984)
(A)
Fig.
2.
UTP tension above in
11
(B)
(A)
in
Chronotropic
isolated
dog
development, each
point.
canine
present
the
Each
and
vertical
Control
preparations.
paced
and atria.
(B) ventricles.
S.E.M.
inotropic
sinus Inotropic Each
Control
tension
effects
point bars rate
ncreasing the
represent before
effects point
of
represents
the
UTP of
developed
of
S.E.M.;
the was
chronotropic changes were not significant in the dog heart (4). In this study, we confirmed that UTP does not have any significant chronotropic effect, and we demonstrated that UTP induces a negative inotropic effect, which is not mediated via cholinergic mechanisms. Singh and Flitney (3) showed that UTP produced only a positive inotropic effect on the isolated frog ventricle when superfused, which was unaffected by adrenergic receptor antagonists. In the frog ventricle, UTP did not produce the negative inotropic effect, but in the dog atrium and ventricle, we demonstrated the negative inotropic effect of UTP. The reason for the difference in the results is not readily apparent, but may be due to a species difference or to differences in experimental conditions. It is concluded that UTP induces both negative and positive chronotropic effects and
of
of
mean
of
1.5•}0.3
g
changes
number
was
doses
norepinephrine,
maximum the
administration
increasing
represents
doses
mean
of
95•}3.8
adenosine
maximum (mean•}S.E.M.)
adenosine in
sinus
observations beats/min
and
UTP
changes,
is
and
in
indicated
(mean•}S.E.M.) in and
in
and
rate
the
isolated
vertical
and bars
re-
5 preparations.
also has inotropic effects, the predominant effect, however, being the negative inotropic effect. Acknowledgment: This study was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education. Science and Culture of Japan (Grant No. 58570089). References 1 Versprill, A.: The influence of uridine nucleotides upon the isolated frog heart. Pfluegers Arch. Ges. Physiol. 277, 285-292 (1963) 2 Flitney, F.W. and Singh, J.: Exogenous uridine 5'-triphosphate (UTP) enhances conctractility and stimulated 3`,5'-cyclic nucleotide metabolism in the frog ventricle. J. Physiol. (Lond.) 291, 52P-53P (1979) 3 Singh, J. and Flitney, F.W.: Effects of uridine triphosphate on contractility, cyclic nucleotide levels and membrane potential in the isolated frog ventricle. Pfluegers Arch. Ges. Physiol.
Short Communications
392, 1-6 (1981) 4 James, T.N.: The chronotropic action of ATP and related compounds studied by direct perfusion of the sinus node. J. Pharmacol. Exp. Ther. 149, 233-247 (1965) 5 Chiba, S., Kimura, T. and Hashimoto, K.: Muscarinic suppression of the nicotinic action of acetylcholine on the isolated, blood-perfused atrium of the dog. Arch. Pharmacol. 289, 31 5325 (1975) 6 Chiba, S.: Effect of pentobarbital, verapamil and manganese on the frequency-force relationship of the isolated atrium and ventricle of the dog heart. Eur. J. Pharmacol. 40, 225-232 (1976) 7 Chiba, S.: Differences in chronotropic and inotropic responses of canine atrial muscle and
Japan. J. Pharmacol. 35, 337 (1984)
SA node pacemaker activity to adenosine and ACh. Japan. Heart J. 17,73-79 (1976) 8 Chiba, S,, Watanabe, H. and Furukawa, Y.: Inotropic responses of isolated atrial and ventricular muscle from the dog heart to inosine, guanosine and adenosine. Clin. Exp. Pharmacol. Physiol. 8, 171-174 (1981) 9 Burnstock, G.: A basis for distinguishing two types of purinergic receptors. In Cell Membrane Receptor for Drugs and Hormones: A Multidisciplinary Approach, Edited by Straub. R.N. and Bolis, L., p. 107-117, Raven Press, New York (1978) 10 Burnstock, G.: Purinergic receptors in the heart. Circ. Res. 46, Supp. 1, 175-182 (1980)