Ascorbic acid blockade of muscle contractions by neurotransmitters and 2-aminoethanol

On isolated tissues, reducing agents (Ascorbic acid, NaHSO 3) antagonized contractile responses of ACH, NE, ISO and 2-aminoethanol. Oxidizing agent, (NH 4) 2S 2O 8 abolished muscle relaxations produced by NE and Mg. Biogenic amines, catechol, hydroquinone and ascorbic acid which produced muscle relaxations also reduced oxidized cytochrome C, whereas ACH, 2-aminoethanol and (NH 4) 2S 2O 8 which produced contractions did not. It appears that the aromatic rings of biogenic amines behave as reducing portions of the molecules causing muscle relaxations and the aminoethyl side chains act as oxidizing portions causing contractions. The relative effectiveness of the oxidizing and reducing portions of the molecule in any given tissue may therefore account for the ability of biogenic amines to produce relaxations in one tissue and contractions in the other.