S-Space College of Medicine/School of Medicine (의과대학/대학원) Dept. of Medicine (의학과) The Seoul Journal of Medicine The Seoul Journal of Medicine Vol. 21 No.3 (1980)
아데노신의 혈관 평활근에 대한 작용기전
Basic mechanism of adenosine-induced responses in isolated vascular smooth muscle
- Issue Date
- 서울대학교 의과대학
- Seoul J Med, Vol.21 No.3, pp. 291-299
- Adenosine, a potent coronary vasodilator. has been
known to be endogenously formed and released from
the rnyocardiac cells and to induce coronary vasodilation
when the oxygen supply to the myocardium is
reduced. However, the mechanism of adenosine-induced
relaxation of coronary vascular smooth muscle
has not yet been clarified.
The inhibitory mechanisms of adenosine on the
activated strips by electrical field stimulation, high
K·Tyrode solution, or acetylcholine were studied in
isolated pig coronary artery. Helical strips of arterial
muscle were prepared from the extramural and
intramural coronary artery of pigs. All experiments
were performed in HC03--buffered Tyrode solution
which was aerated with 396 CO2- 9796 O2 mixed
gas and kept at 35'C.
The phasic contractions induced by electrical field
stimulation CA.C" 60Hz, 5V /cm, duration 15 sec,
period 3 min) were suppressed by the addition of
adenosine. Both passive resting tension and active
tension were rapidly decreased after the addition of
adenosine to bathing Tyrode solution, but the active
phasic contractions were gradually recovered from
the adenosine'induced depression of contractility.
Adenosine did not exhibit tachyphylaxis.
Adenosine also suppressed K-contractures in a dose-dependent manner, which were developed mainly by
the increase of Ca influx. This inhibitory action of
adenosine on K-contracture was more potent and
preferentially in small intramural coronary strips
than in large extramural coronary strips, and was
inversely related to the degree of membrane depolarization.
Differential effects of adenosine on the
relaxing responses of large and small coronary arteries
suggest the possibility of an existence of a surface
adenosine receptor on coronay myocytes.
The component of contraction curve, associated
with the release of bound Ca and induced by ace'
tylcholine, was obviously suppressed by the adminis·
tration of adenosine.
The results of this experiment suggest that the
adenosine-induced relaxation of coronary vascular
smooth muscle was developed by inhibiting trans'
membrane Ca influx and/or interfering intracellular
release of Ca.