Alpha 2C-adrenoceptor-modulated release of noradrenaline in human right atrium

British Journal of Pharmacology
L C RumpN Limberger

Abstract

1. The aim of the present study was to characterize the presynaptic alpha 2-autoreceptors in human right atrium in terms of the alpha 2A-D system. Segments of atrial appendages were preincubated with [3H]-noradrenaline and then superfused in the presence of cocaine and stimulated electrically. pEC30% values of eight alpha-adrenoceptor antagonists with discriminatory power were determined. pEC30% is the negative logarithm of the antagonist concentration that increased the stimulation-induced overflow of tritium by 30%. For four antagonists, the dissociation constant KD was determined, in addition to pEC30%, against the overflow-inhibiting effect of 5-bromo-6-(2-imidazolin-2-ylamino)-quinoxaline (UK 14,304) under autoinhibition-free conditions. 2. pEC30% and KD values yielded identical rank orders of antagonist affinity (rauwolscine > WB 4101 > phentolamine > prazosin) suggesting that both released noradrenaline and the exogenous agonist UK 14,304 activated the same receptor to inhibit release. 3. The eight antagonist pEC30% values obtained in right atrium correlated significantly with their pEC30% values, reported in the literature, at the presynaptic alpha 2C-autoreceptors in human kidney (r = 0.817; slope of the regression lin...Continue Reading

References

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Citations

Feb 28, 2001·European Journal of Pharmacology·C A RizzoJ A Hey
May 10, 2001·Journal of Molecular and Cellular Cardiology·J D Port, M R Bristow
Sep 1, 2001·Pharmacological Research : the Official Journal of the Italian Pharmacological Society·B Civantos Calzada, A Aleixandre de Artiñano
Apr 14, 2006·Journal of Pharmacological Sciences·Otto-Erich BroddeKirsten Leineweber
Jul 11, 2001·Journal of Cardiovascular Pharmacology·M GrimmG Richardt
Sep 2, 2008·American Journal of Physiology. Heart and Circulatory Physiology·Tadayoshi MiyamotoMasaru Sugimachi
Apr 13, 2004·The Journal of Pharmacology and Experimental Therapeutics·Rouwayda El-AyoubiSuhayla Mukaddam-Daher
May 1, 1997·Journal of Cardiovascular Pharmacology·L C RumpP Schollmeyer
Sep 16, 2000·Hypertension·G J MolderingsM Göthert
Jul 18, 2002·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Melanie PhilippLutz Hein
Dec 16, 1998·European Journal of Pharmacology·J R Docherty

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