Molecular Pharmacology, Vol 3, 28-36, Copyright © 1967 by the American Society for Pharmacology and Experimental Therapeutics

Studies on the Noradrenaline -Receptor

II. Analysis of the "Spare-Receptor" Hypothesis and Estimation of the Concentration of -Receptors in Rabbit Aorta

¹ Theoretical Biology Unit, School of Pharmacy, State University of New York at Buffalo, Buffalo, New York 14214

The rates of recovery of response of rabbit aortic strips, blocked with N,N-dimethyl-2-bromo-2-phenylethylamine, to noradrenaline, adrenaline, N-ethyl- and N-isopropyl-noradrenaline have been determined. The close similarities of these recovery rates suggests that "spare" receptors are of little significance in this system.

The use of ³H-labeled N,N-dimethyl-2-bromo-2-phenylethylamine enabled an estimate of the concentration of -receptors, 1.15 x 10¹² receptors per milligram of tissue dry weight, to be made and also provided good evidence for the view that tissue response is proportional to the concentration of agonist-receptor complex.

Note:
ACKNOWLEDGMENTS The authors wish to acknowledge the assistance of Miss Marlene Calderone. This investigation was supported by a grant from the National Institute of Health, U. S. Public Health Service (GM 11603).