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KMID : 0365819830230010167
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Journal of Pusan Medical College
1983 Volume.23 No. 1 p.167 ~ p.178
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Mode of Action of Pentobarbtal on Isolated Vascular Smooth Muscle
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Abstract
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Pentobarbital, effective in lowering raised intracranial pressure, has been known to have vaso- dilatatory effect on blood vessel. However, the mechanism of pentobarbital-induced relaxation of the vascular smooth muscle has not yet been clarified.
The inhibitory mechanisms of pentobarbital on the contractility of arterial segment strips induced by electrical field stimulation, high K-Tyrode solution, norepinephrine(NE), and serotonin(5-HT) were studied in isolated cat carotid artery segments. All experiments were performed in Tris-buffered Tyrode solution which was aerated with 100% O2 gas and kept at 37t.
1 . The phasic contractions induced by electrical field stimulation(A. C. , 20 Hz, 60V/cm, duration 15 sec, period 10 min) were suppressed by the addition of pentobarbital. Both passive resting tension and active tension were rapidly decreased after the addition of pentobarbital to bathing Tyrode solution.
2. Pentobarbital also suppressed K-contractures in a dose-dependent manner, which were developed mainly by the increase of Cal´ influx. This inhibitory action of pentobarbital on K-contracturewas inversely related to [K?] of the medium.
3. Pentobarbital suppressed NE and 5-HT-induced contraction in a dose-dependent manner.
4. The contraction curve in the Ca-free medium, probably associated with the release of bound Ca, was suppressed by the administration of pentobarbitaL
The results of this experiment suggest that the pentobarbital-induced relaxation of carotid vascular smooth muscle was developed by inhibiting transmembrane Cat` influx and/or interfering intracellular release of Cal*.
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