Effect of tetraethylammonium and barium on the release of noradrenaline from the perfused cat spleen by nerve stimulation and potassium

1976 ◽  
Vol 294 (1) ◽  
pp. 23-29 ◽  
Author(s):  
S. M. Kirpekar ◽  
Arun R. Wakade ◽  
J. C. Prat
Keyword(s):  
Nerve Stimulation ◽  
Release Of Noradrenaline ◽  
Cat Spleen

scholarly journals Release of noradrenaline from the cat spleen by nerve stimulation and potassium.

1976 ◽  
Vol 261 (2) ◽  
pp. 301-317 ◽  
Author(s):  
A G Garcia ◽  
S M Kirpekar ◽  
P Sanchez-Garcia
Keyword(s):  
Nerve Stimulation ◽  
Release Of Noradrenaline ◽  
Cat Spleen

What do antagonists tell us about α-adrenoceptors?

1985 ◽  
Vol 68 (s10) ◽  
pp. 15s-19s ◽  
Author(s):  
G. M. Drew
Keyword(s):  
Nerve Stimulation ◽  
Sympathetic Nerve ◽  
Isolated Heart ◽  
Coupling Mechanism ◽  
Sympathetic Nerve Stimulation ◽  
Stimulus Response ◽  
Adrenoceptor Agonist ◽  
Tissue Responses ◽  
Cat Spleen ◽  
Relative Potencies

The early proposals that pre- and post-junctional α-adrenoceptors might be different stemmed largely from two separate observations. Firstly, the orders of potency of a series of agonists at inhibiting the response to sympathetic nerve stimulation and in increasing inotropic activity in the rabbit isolated heart were different [1, 2]. Secondly, phenoxybenzamine was more potent in inhibiting vasoconstrictor responses to sympathetic nerve stimulation than in increasing transmitter overflow from the cat spleen [3]. These experiments illustrate the most fundamental, pharmacological ways of distinguishing between receptors: namely, by comparing the relative potencies of agonists and/or antagonists in producing, or preventing, pharmacological effects. There are, however, difficulties in using agonists to classify receptors because their ability to generate a response depends not only upon their intrinsic properties of affinity for, and efficacy at, the receptors but also upon the capacity of the tissue to translate the stimulus into a response. Thus agonists with a relatively low intrinsic efficacy may produce a small response, or no response at all, in a tissue in which the efficiency of the stimulus-response coupling mechanism is low. The importance of this phenomenon in influencing tissue responses to agonists with low efficacy has been demonstrated for the α-adrenoceptor agonist prenalterol [4] and for the α-adrenoceptor agonist oxymetazoline [5].

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