• DOI:10.1152/AJPLEGACY.1948.153.3.586
• Corpus ID: 1518772

A study of the adrenotropic receptors.

@article{Ahlquist1948ASO,
  title={A study of the adrenotropic receptors.},
  author={Raymond P. Ahlquist},
  journal={The American journal of physiology},
  year={1948},
  volume={153 3},
  pages={
          586-600
        }
}

• R. P. Ahlquist
• Published 1 June 1948
• Biology
• The American journal of physiology

T HE adrenotropic receptors are those hypothetical structures or systems located in, on or near the muscle or gland cells affected by epinephrine. The concept of a receptive mechanism was introduced by Langley (I, 2) to explain the action of curare on skeletal muscle. Dale was probably the first to make significant use of the receptor concept in connection with the sympathetic nervous system. In his classical paper (3) on the sympatholytic action of the ergot alkaloids, he recognized that what he called the sympathetic myoneural junction could also be called 'the receptive mechanism for adrenaline'; and he used this mechanism to explain the fact that the ergot alkaloids prevented only the motor (excitatory) actions of epinephrine and had no effect on the inhibitory actions of epinephrine or on the excitatory actions of barium or pituitrin. The adrenotropic receptors have been considered to be of two classes, those whose action results in excitation and those whose action results in inhibition of the eff ector cells. Experiments described in this paper indicate that although there are two kinds of adrenotropic receptors they cannot be classified simply as excitatory or inhibitory since each kind of receptor may have either action depending upon where it is found. The evidence for these conclusions is, in brief, that a series of six sympa-thomimetic amines has one order of potency-r, 2, 3, 4, 5, 6-on the following functions: vasoconstriction, excitation of the uterus and ureters, contraction of the nictitating membrane, dilation of the pupil and inhibition of the gut. In contrast, this same series of amines has an entirely different order of potency-z, 4, 6, 5, 3, Ion the following functions: vasodilation, inhibition of the uterus and myocardial stimulation. The variations in activity could be due to any or all of three factors: a) quantitative differences in potency, b) qualitatively different effects or c) differences due entirely to the experimental methods used. If the last Tao factors are controlled as much as possible by the selection of the amines and by using suitable experimental techniques, then the variations in activity are presumably due to actual differences in the receptors involved. Tentatively the first kind of receptor has been called the alpha adrenotropic receptor and the second kind the beta receptor. This concept of two fundamental types of receptors is directly opposed to the concept of two mediator substances (sympathin E and sympathin I) as propounded by …