Effects of l-Methionine, Reserpine and Some Autonomic Drugs on the Tracheal Muscle of Guinea-Pigs
1964 Volume 16 Issue 1 Pages 68-82
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1964 Volume 16 Issue 1 Pages 68-82
The responses of the tracheal muscle to l-methionine, reserpine, isopropylnoradrenaline and other related drugs were examined in vitro by using chain preparations made from guinea-pig trachea. The results were as follows:
(1) Isopropylnoradrenaline (10-5g/ml), adrenaline (10-5g/ml), Alotec (1-(3,5dihydroxyphenyl)-2-isopropylaminoethanol-1/2H2SO4) (10-5g/ml), noradrenaline (10-5: g/ml) and ephedrine (10-4g/ml) decreased the tone of the tracheal muscle. The former three drugs were found to be more potent than the latter two drugs in the induction of tracheal relaxation. The recovery of tracheal response, when the drug containing bath was changed to Lock's solution, occurred slowly in the cases of isopropylnoradrenaline, Alotec and ephedrine.
(2) Acetylcholine (10-6g/ml) and histamine (10-5g/ml) caused tracheal contraction. Nicotine (10-4g/ml) relaxed the tracheal muscle after a transient and slight contraction. In comparison with tracheal chain preparations made from untreated animals, tracheal chain preparations made from animals pretreated with reserpine (1mg/kg) 20 to 24 hours before the experiment showed a markedly reduced response to nicotine.
(3) In the presence of l-methionine (3×10-3)the tone of the tracheal muscle slowly increased to reach its maximum level about one hour after the application of the drug. The effect of l-methionine was not counteracted by reserpine or atropine.
(4) Contrary to the case of l-methionine, reserpine (3×10-5g/ml)slowly decreased the tone of the tracheal muscle.
(5) Tracheal relaxation by means of adrenaline (2×10-5g/ml)was augmented in the presence of catron (10-7g/ml), but not in the presence of pyrogallol (10-7g/ml). The effcet of adrenaline or acetylcholine on the tracheal muscle was augmented in the presence of l-methionine(3×10-3g/ml), while it was reduced in the presence of reserpine (3×10-5g/ml).
(6) The contraction of the tracheal muscle caused by l-methionine (3×10-3g/ml)was reversed to relaxation after the addition of adrenaline (10-5g/ml), noradrenaline. (10-5g/ml), isopropylnoradrenaline (10-5g/ml) or Alotec (10-5g/ml), but n ot after theaddition of ephedrine (5×10-4g/ml), reserpine(3×10-5g/ml) or atropine (10-6g/ml).
From these observations it may be concluded that l-methionine serves to promotethe autonomic mechanism of the tracheal muscle and also to accelerate tracheal muscle contractility independent of its cholinergic mechanism, while reserpineacts to depress these physiologic mechanisms of the tracheal muscle.
