Molecular Pharmacology, Vol 2, 501-505, Copyright © 1966 by the American Society for Pharmacology and Experimental Therapeutics

Blockade of Norepinephrine-Induced Lipolysis by Isomers of dl-1-(Nitrophenyl)-1-Hydroxy-2-Isopropylaminoethane

¹ Department of Pharmacology, Marquette University School of Medicine, Milwaukee, Wisconsin 53233

The ability of three new beta adrenergic blocking agents, dl-1-(2-nitrophenyl)-1-hydroxy-2-isopropylaminoethane (2-INPEA), dl-1-(3-nitrophenyl)-1-hydroxy-2-isopropylaminoethane (3-INPEA), and dl-1-(4-nitrophenyl)-1-hydroxy-2-isopropylaminoethane (4-INPEA) to antagonize norepinephrine-induced lipolysis was investigated utilizing an isolated fat cell preparation. All three isomers were capable of blocking norepinephrine competitively. The pA₁₀ values for 2-INPEA, 3-INPEA, and 4-INPEA were determined and concentration-inhibition curves were plotted. 4-INPEA was found to be approximately ten times as potent as 2-INPEA and 3-INPEA, the latter two being equipotent. The results are discussed in relation to the classification of the adrenergic receptor in adipose tissue.

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ACKNOWLEDGMENT We wish to thank Mrs. Esther Nadolny for her technical assistance. This work was supported by USPHS grants HEO 7564 and AMO 7681.