PMID: 6113551Apr 1, 1981Paper

Multiple effects of putative alpha-adrenoceptor agonists on the electrical and mechanical activity of guinea-pig papillary muscle

Naunyn-Schmiedeberg's Archives of Pharmacology
J Sanchez-Chapula

Abstract

The effects of the putative alpha-adrenoceptor agonists phenylephrine, methoxamine and clonidine on force of contraction and on calcium-dependent action potentials were studied in guinea-pig papillary muscles. Phenylephrine increased the force of contraction by stimulating alpha-adrenoceptors as well as beta-adrenoceptors. It increased the amplitude and duration of slow action potentials, but this effect was exclusively due to stimulation of beta-adrenoceptors. The positive inotropic effect mediated by alpha-adrenoceptors can presumably not be explained by an increase in calcium influx during the action potential via the slow inward current. Methoxamine had no effect on the force of contraction at 10(-5) and 10(-4) mol/l, but at 10(-4) mol/l it slightly decreased amplitude and duration of slow action potentials. Clonidine produced a large increase in force of contraction and in amplitude and duration of slow action potentials. These effects were due to stimulation of H2-histamine receptors. It is concluded that in guinea-pig papillary muscle the tested putative alpha-adrenoceptor agonists do not share a common alpha-adrenoceptor effect, but produce prominent effects which are mediated through either beta-adrenoceptors (phenylep...Continue Reading

References

Sep 1, 1977·Life Sciences·S Berthelsen, W A Pettinger
Sep 1, 1975·The American Journal of Physiology·B RabinowitzW W Parmley
Mar 16, 1978·Naunyn-Schmiedeberg's Archives of Pharmacology·M Korth
May 1, 1975·British Journal of Pharmacology·F LeddaA Mugelli
Apr 5, 1974·Naunyn-Schmiedeberg's Archives of Pharmacology·A Csongrady, W Kobinger
Apr 5, 1974·Naunyn-Schmiedeberg's Archives of Pharmacology·T MeinertzK Winter
Apr 21, 1964·Naunyn-Schmiedebergs Archiv für experimentelle Pathologie und Pharmakologie·J R BLINKS

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Citations

Dec 1, 1985·Naunyn-Schmiedeberg's Archives of Pharmacology·J Sánchez-Chapula
Jan 1, 1984·Naunyn-Schmiedeberg's Archives of Pharmacology·Y Miura, J Inui
Sep 11, 1981·European Journal of Pharmacology·J Sanchez-Chapula
Jan 1, 1988·Progress in Biophysics and Molecular Biology·H C Hartzell
Jan 1, 1982·General Pharmacology·A G TahilianiJ H McNeill
Jun 1, 2015·Journal of Pharmacological and Toxicological Methods·Rob WallisHelen Maddock
Dec 30, 2008·American Journal of Physiology. Heart and Circulatory Physiology·Katy RivardCéline Fiset

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