alpha 1-adrenoceptor activation can increase heart rate directly or decrease it indirectly through parasympathetic activation

British Journal of Pharmacology
N A Flavahan, J C McGrath


1 The chronotropic effects of alpha- and beta-adrenoceptor agonists were investigated in the pithed rat. 2 The beta-adrenoceptor agonist, isoprenaline, produced only a positive chronotropic response. alpha 1-Adrenoceptor agonists, phenylephrine and amidephrine, produced positive and negative chronotropic effects. Part of the response to phenylephrine was beta-mediated. 3 A positive chronotropic response to amidephrine and phenylephrine was mediated directly through cardiac alpha 1-adrenoceptors and had a different time course from beta-adrenoceptor-mediated responses. 4 A negative chronotropic response to alpha-agonists was potentiated by neostigmine and blocked by atropine, tetrodotoxin or hexamethonium as well as by alpha 1-adrenoceptor antagonists. This may indicate alpha 1-adrenoceptors on preganglionic parasympathetic nerves, stimulation of these receptors causing release of acetylcholine. 5 The alpha 2-adrenoceptor agonist, xylazine, produced a direct negative chronotropic effect on the heart, independent of alpha-adrenoceptors. No evidence was found for functional post-junctional alpha 2-adrenoceptors. At high doses xylazine stimulated cardiac alpha 1-adrenoceptors.


Dec 1, 1978·European Journal of Pharmacology·M Butler, D H Jenkinson
May 5, 1978·Naunyn-Schmiedeberg's Archives of Pharmacology·J Wagner, O E Brodde
Aug 1, 1977·Japanese Journal of Pharmacology·S Chiba
Apr 30, 1979·Naunyn-Schmiedeberg's Archives of Pharmacology·W KobingerL Pichler
Jan 1, 1978·Naunyn-Schmiedeberg's Archives of Pharmacology·T Bennett, P A Kemp
Aug 1, 1972·British Journal of Pharmacology·J B FarmerR J Marshall
Apr 1, 1972·Japanese Journal of Pharmacology·M Nakashima, Y Hagino
Jul 1, 1981·Journal of Cardiovascular Pharmacology·J R Docherty, K Starke
Oct 1, 1980·Canadian Journal of Physiology and Pharmacology·B G Benfey
Jul 1, 1981·British Journal of Pharmacology·N A Flavahan, J C McGrath

❮ Previous
Next ❯


Jun 1, 1985·Naunyn-Schmiedeberg's Archives of Pharmacology·G Gross, I Lues
Nov 1, 1987·Pflügers Archiv : European journal of physiology·P BorgdorffA Cevese
Jan 1, 1986·European Journal of Applied Physiology and Occupational Physiology·P G Versteeg, P Borgdorff
Jul 17, 1985·European Journal of Pharmacology·P WarnockJ R Docherty
Jan 1, 1985·Comparative Biochemistry and Physiology. C, Comparative Pharmacology and Toxicology·K W Chiu, J S Sham
Jan 1, 1989·Comparative Biochemistry and Physiology. C, Comparative Pharmacology and Toxicology·K W Chiu, J Y Chu
Aug 1, 1986·Clinical and Experimental Pharmacology & Physiology·J VincentJ L Reid
Jan 1, 1988·Clinical and Experimental Pharmacology & Physiology·A De Luca, M J Rand
Jan 1, 1996·Canadian Journal of Physiology and Pharmacology·R Igić
Nov 27, 2007·European Journal of Pharmacology·Rapheeporn KhwanchueaChaweewan Jansakul
Nov 5, 2016·Toxicon : Official Journal of the International Society on Toxinology·Lourdes DiasStephen Hyslop
Oct 1, 1989·Medicinal Research Reviews·J C McGrathV G Wilson
Jan 1, 1990·Life Sciences·B G Benfey

❮ Previous
Next ❯

Related Concepts

Related Feeds

Adrenergic Receptors: Trafficking

Adrenergic receptor trafficking is an active physiological process where adrenergic receptors are relocated from one region of the cell to another or from one type of cell to another. Discover the latest research on adrenergic receptor trafficking here.

Cardiac Electrophysiology

Cardiac electrophysiology is the study of electrical activities of the heart and includes the assessment, diagnosis, and treatment of cardiac events. Find the latest research on cardiac electrophysiology here.