PMID: 41191Sep 1, 1979

Demonstration of alpha-adrenoceptors in the rabbit heart by [3H]-dihydroergocryptine binding

Naunyn-Schmiedeberg's Archives of Pharmacology
H J Schümann, O E Brodde

Abstract

For direct identification of alpha-adrenoceptors in a membrane fraction of the rabbit heart the potent alpha-adrenoceptor antagonist [3H]-dihydroergocryptine ([3H]-DHE) was used. 1. The binding of [3H]-DHE was saturable with 80 fmol of [3H]-DHE bound/mg protein and of high affinity with an equilibrium dissociation constant (KD) of 11.5 nM. Binding of [3H]-DHE (6 nM) was rapid (t 1/2 = 2 min) and readily reversible. From the ratio of the rate constants for forward (K1 = 1.97 X 10(7) M-1 min-1) and reverse (K2 = 0.206 min-1) reactions a KD-value of 10 nM was calculated, which is in good agreement with that obtained by equilibrium studies. 2. Adrenergic agonists compete for [3H]-DHE binding in an order to potency: (-)adrenaline greater than (-)phenyleprine greater than (-)isoprenaline and adrenergic antagonists in the order: phentolamine greater than yohimbine greater than (-)propranolol. Binding is stereospecific as indicated by the greater potency of (-)adrenaline than (+/-)adrenaline in displacing [3H]-DHE from the binding sites. 3. For comparison the binding of the potent beta-adrenoceptor antagonist (-)[3H]-dihydroalprenolol ((-)[3H]-DHA) was measured in the same membrane fraction. The number and affinity of beta-adrenoceptor...Continue Reading

References

Dec 17, 1976·Naunyn-Schmiedeberg's Archives of Pharmacology·W KrawietzC Konrad
Feb 1, 1978·The Journal of Clinical Investigation·K D NewmanR J Lefkowitz
Apr 1, 1978·British Journal of Pharmacology·M AggerbeckJ Hanoune
Mar 1, 1979·Journal of Cardiovascular Pharmacology·R S Williams, R J Lefkowitz
Dec 1, 1975·European Journal of Pharmacology·K StarkeT Endo
Aug 26, 1977·Brain Research·J N DavisR J Leefkowitz
May 5, 1978·Naunyn-Schmiedeberg's Archives of Pharmacology·J Wagner, O E Brodde
May 5, 1978·Naunyn-Schmiedeberg's Archives of Pharmacology·H J SchümannG Schramm
Dec 1, 1978·Proceedings of the National Academy of Sciences of the United States of America·P GuicheneyP Meyer
Feb 7, 1977·Biochemical and Biophysical Research Communications·T Ciaraldi, G V Marinetti
Apr 1, 1975·Proceedings of the National Academy of Sciences of the United States of America·R W AlexanderR J Lefkowitz
Jan 1, 1976·The Journal of Clinical Investigation·L T WilliamsR J Lefkowitz
Apr 24, 1974·Naunyn-Schmiedeberg's Archives of Pharmacology·J WagnerD Reinhardt
Jan 1, 1972·Naunyn-Schmiedeberg's Archives of Pharmacology·K Starke

Citations

Jul 1, 1984·Naunyn-Schmiedeberg's Archives of Pharmacology·R R RuffoloJ S Horng
May 1, 1985·Pharmacology, Biochemistry, and Behavior·R R Ruffolo
Jan 1, 1981·Comparative Biochemistry and Physiology. C: Comparative Pharmacology·G Stene-Larsen
Mar 1, 1988·Archives internationales de physiologie et de biochimie·Y SarioğluS O Kayaalp
Feb 12, 1996·FEBS Letters·H C LeeJ J Cai

Related Concepts

Adrenergic alpha-Agonists
Adrenergic alpha-Antagonists
Ergot Alkaloids, Hydrogenated
Heart
Tissue Membrane
Norepinephrine Receptors
Beta-adrenergic receptor

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