Dopamine 2 (DA‐2) Receptor Assays Using Sympathetic Nerve Terminals

John P. Long1

1 University of Iowa, Iowa City, Iowa
Publication Name:  Current Protocols in Pharmacology
Unit Number:  Unit 4.14
DOI:  10.1002/0471141755.ph0414s06
Online Posting Date:  May, 2001
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Abstract

In vitro experiments using isolated atria with and without superfusion can be used to quantify the dopamine‐2 (DA‐2) receptor stimulating activity of compounds. This receptor mechanism decreases the amount of norepinephrine released from sympathetic nerve terminals by neuronal impulses. DA‐2 receptor agonists (stimulants) are very active and induce several physiological changes, such as bradycardia, hypotension, lower intraocular pressure, etc. In this unit, tissue preparation and dopamine receptor assays are described for isolated cat atria with field stimulation or with superfusion, and isolated guinea pig atria with field stimulation.

     
 
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Table of Contents

  • Basic Protocol 1: Evaluation of DA‐2 Receptor Activity in Isolated Cat Atria with Field (Transmural) Stimulation
  • Alternate Protocol 1: Evaluation of DA‐2 Receptor Activity in Isolated Guinea Pig Atria with Field Stimulation
  • Alternate Protocol 2: Evaluation of DA‐2 Receptor Activity in Isolated Cat Atrium with Superfusion
  • Reagents and Solutions
  • Commentary
  • Literature Cited
  • Figures
  • Tables
     
 
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Materials

Basic Protocol 1: Evaluation of DA‐2 Receptor Activity in Isolated Cat Atria with Field (Transmural) Stimulation

  Materials
  • Feigen's solution (see recipe)
  • 95% O 2/5% CO 2 (carbogen) source, for oxygenating Feigen's solution
  • Adult cats weighing 2 to 3 kg, either sex
  • Pentobarbital sodium
  • 0.9% (w/v) NaCl (saline)
  • DA‐2 receptor agonist: e.g., 1 mM apomorphine HCl (Mallinckrodt)
  • DA‐2 receptor antagonist: e.g., 1 mM haloperidol (McNeil) or 1 mM (−)‐sulpiride (McNeil)
  • 100‐ml isolated tissue bath surrounded by larger heating bath
  • Perfusion pump (Sigmamotor Model T‐8)
  • Strain gauge
  • Recorder (Offner type RS)
  • Surgical equipment, 4‐0 silk thread, and other surgical supplies (see unit 4.2)
  • Evaporating dish for tissue dissection
  • 0.1‐, 1‐, 5‐ and 10‐ml syringes
  • 1/2‐in., 25‐G needle
  • 4‐ to 6‐cm‐long wire or flat electrodes made of platinum, silver, or stainless steel, for stimulation
  • Grass S48 stimulator and Grass SIU5 stimulus‐isolation unit
  • Strain gauge (Statham GT‐03)
  • Cardiotachometer (Beckman Model 9873)

Alternate Protocol 1: Evaluation of DA‐2 Receptor Activity in Isolated Guinea Pig Atria with Field Stimulation

  • Adult guinea pigs weighing 300 to 400 g, either sex, any strain
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Figures

Videos

Literature Cited

   Ernst, A.M. 1967. Mode of action of apomorphine and dextroamphetamine on gnawing compulsion in rats. Psychopharmacologia 10:316‐324.
   Finney, D.J. 1962. Probit Analysis, 2nd ed. Cambridge University Press, New York.
   Ilhan, M., Long, J.P., and Cannon, J.G. 1984. Dopaminergic activity of a nonhydroxylated aminotetralin derivative (TL‐69) on cat heart. Arch. Int. Pharmacodyn. 271:213‐219.
   Long, J.P., Bhatnagar, R.K., Chatterjee, T., Flynn, J.R., and Cannon, J.G. 1990. Inhibition of cardiac neurotransmission in vivo and in vitro by structural analogs of dopamine. In Cardiovascular Function of Peripheral Dopamine Receptors (J.P. Hieble, ed.) pp. 103‐132. Marcel Dekker, New York and Basel.
   Whitacre, T.S., Long, J.P., and Whalen, W.J. 1966. Transmural and vagal nerve stimulation of the right atrium of the cat. Am. J. Physiol. 210:557‐562.
Key References
   Finney, 1962. See above.
  Statistical bases for valid bioassay and calculation of data.
   Goldstein, A. 1964. Biostatistics: An Introductory Text. Macmillan, New York.
  An excellent reference for analysis of variances, LD50, ED50, and related concepts.
   Whitacre et al., 1966. See above.
  Detailed discussion of the use of isolated cat atrial preparations, including temperature and optimal pulse frequency, among other parameters.
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