α-ADRENERGIC BLOCKING ACTION OF NOREPHEDRINE-THEOPHYLLINE (NET) OBSERVED IN THE RENAL VASCULAR RESPONSE

Abstract

Norephedrinetheophylline (NET), l-7[2-(1-methyl-2-hydroxy-2-phenyl-ethylamino)ethyl] theophylline hydrochloride, has molecules of caffeine and ephedrine in its chemical structure as follows: Since diuretic effects of aminoalkyl derivatives of theophylline were investigated by Hildebrandt (1) in 1952, pharmacological properties of these compounds have been elucidated by several workers (2, 3). Among these derivatives, NET was specially studied by Wagenmann and Taugner (4) and Mehmel et al. (5) on its cardiovascular effect. When caffeine and ephedrine are combined to NET, the pharmacological properties are very different from those of caffeine and ephedrine. NET does not show such a marked stimulatory effect on the central nervous system as that of constituents, and its positive chronotropic effect is very slight or converted to the negative one. These observations were attracting the authors' attention to test competition between this compound and catecholamines which seemed likely as a cause of diminution of the cardiovascular effect of this compound. The authors selected the renal vascular bed which is most sensitive to the adrenergic varoconstrictor action and very suitable to test α-adrenergic blocking effect of this compound.