ALTERATIONS OF ADRENERGIC RESPONSES BY N-ISOPROPYLMETHOXAMINE

¹ Department of Pharmacology, New York Medical College, Flower-Fifth Avenue Hospitals, New York, N. Y.

We have found that N-isopropylmethoxarnine (IMA) and methoxamine are not typical beta adrenergic receptor blocking agents. They differ from dichloroisoproterenol (DCI) and nethalide in that they do not block any of the responses to beta adrenergic receptor activation in the anesthetized dog. However, in the isolated rat uterus, IMA and methoxamine produce a blockade of the catecholamine induced inhibitory response that is specific and that resembles closely the blockade produced by DCI and nethalide.

We have previously reported that the rat uterus possesses only beta adrenergic inhibitory receptors. IMA and methoxamine have also been reported to produce a blockade of the catecholamine induced increase in glucose and free fatty acids. This is a blockade that is also produced by the classical beta adrenergic receptor blocking agents DCI and nethahide. Two possible explanations are cited. First, IMA and methoxamine might be considered to be more specific beta adrenergic receptor blocking agents than DCI and nethalide in that they block beta adrenergic receptors only in certain tissues. Second, the receptor of the rat uterus is a different type of beta adrenergic receptor in that it is blocked by IMA and methoxamine as well as DCI and nethalide.

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				{beta}-Blockers Continued from page 21 Perspectives in Public Health, February 1, 1978; 98(1): 48 - 49.