Evidence against beta-adrenoceptor blocking activity of diltiazem, a drug with calcium antagonist properties

British Journal of Pharmacology
M BrileyA G Roach

Abstract

1 The isolated spontaneously beating atria of the rat, diltiazem (0.01 to 0.1 microM) shifted the atrial rate concentration-response curves to isoprenaline to the right in a non-parallel manner and depressed their maxima. Under the same experimental conditions, (+/-)-propranolol (0.03 to 0.1 microM) behaved as a competitive beta-adrenoceptor antagonist. 2 Whereas (+/-)-propranolol (IC50 = 12 nM) and isoprenaline (IC50 = 0.9 microM) inhibited (-)-[3H]-dihydroalprenolol binding to rat brain membrane preparations, diltiazem failed to do so in concentrations up to 10 microM. 3 Diltiazem but not (+/-)-propranolol, antagonized the positive chronotropic responses to calcium in spontaneously beating rat atria. 4 It is proposed that diltiazem inhibited the tachycardia induced by isoprenaline through an effect on calcium which may be an essential modulator of the sequence of events linking the beta-adrenoceptor activation and heart rate response.

References

Apr 1, 1977·Japanese Journal of Pharmacology·T MagaribuchiA Kiyomoto
Jun 1, 1977·Japanese Journal of Pharmacology·T MagaribuchiA Kiyomoto
Jun 1, 1973·Japanese Journal of Pharmacology·K YamadaH Nakajima
Feb 1, 1972·Japanese Journal of Pharmacology·T NagaoA Kiyomoto

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Citations

Jan 1, 1984·European Journal of Clinical Pharmacology·J F GiudicelliA Jacolot
Jan 1, 1985·Canadian Anaesthetists' Society Journal·B A Britt
Dec 1, 1980·British Journal of Clinical Pharmacology·H Valette, E Apoil
Apr 6, 2006·European Journal of Pharmacology·Kenneth J Broadley, Peter E Penson
Jun 21, 2005·Journal of Cardiovascular Pharmacology·Christopher P ReganJoseph J Lynch

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