Modification by Islet‐Activating Protein of Direct and Indirect Inhibitory Actions of Adenosine on Rat Atrial Contraction in Relation to Cyclic Nucleotide Metabolism

  title={Modification by Islet‐Activating Protein of Direct and Indirect Inhibitory Actions of Adenosine on Rat Atrial Contraction in Relation to Cyclic Nucleotide Metabolism},
  author={M. Endoh and M. Maruyama and N. Taira},
  journal={Journal of Cardiovascular Pharmacology},
Summary Adenosine decreased the force of contraction of isolated rat left atria (direct action) and inhibited the positive inotropic action of isoproterenol (indirect action). The direct action of adenosine was not accompanied by changes in cyclic nucleotide levels, while the isoproterenol-induced increase in cyclic AMP level was reduced by the nucleoside. Reserpine pretreatment and pindolol did not affect the direct action of adenosine. Both the direct and indirect actions of adenosine were… Expand
The interaction of adenosine analogues with cAMP-generating and cAMP-independent positive inotropic agents in rabbit left atrium
The data suggest that adenosine receptors in rabbit left atria are not coupled to adenylate cyclase, and their reversal of positive inotropic responses to isoproterenol and forskolin may be mediated by increases in K+ conductance, which have been postulated to shorten the duration of the action potential and reduce the influx of Ca2+. Expand
Pharmacological characteristics of adenosine-induced inhibition of dog ventricular contractility: dependence on the pre-existing level of β-adrenoceptor activation
In the dog ventricular myocardium adenosine receptors play a role for the inhibitory regulation of contractility, which is influenced markedly by the pre-existing level of β-adrenoceptor activation. Expand
Evidence for adenosine receptor-mediated isoprenaline-antagonistic effects of the adenosine analogs PIA and NECA on force of contraction in guinea-pig atrial and ventricular cardiac preparations
It is concluded that in guinea-pig atrial and ventricular cardiac preparations the adenosine analogs PIA and NECA exert isoprenaline-antagonistic effects on force of contraction viaAdenosine receptors the existence of which can be shown in a functional way. Expand
Mechanism of the "Antiadrenergic" Effects of Adenosine on Myocardial Force of Contraction
In isolated electrically driven papillary muscles from guinea pigs adenosine exerted only a small increase and the R site adenosine receptor agonist (−)-N6-phenylisopropyladenosine (PIA) only a smallExpand
Pronounced direct inhibitory action mediated by adenosine A1 receptor and pertussis toxin-sensitive G protein on the ferret ventricular contraction
The present results indicate that adenosine receptors may play an important role in the inhibitory regulation of ventricular contractility in the ferret in contrast to other mammalian species. Expand
The effects of various drugs on the myocardial inotropic response.
  • M. Endoh
  • Chemistry, Medicine
  • General pharmacology
  • 1995
A novel class of cardiotonic agents, namely, Ca 2+ sensitizers such as EMD 53998 and Org 30029, act on the Ca(2+)-binding site of troponin C, increasing the affinity of these sites for Ca2+ ions, or at the actin-myosin interface to facilitate the cycling of cross-bridges. Expand
Positive inotropic effect of bay K 8644: cAMP-independence and lack of inhibitory effect of adenosine
The results support the view that adenosine and PIA only antagonize the positive inotropic effects of drugs known to increase myocardial cAMP content and that an increased myocardian cAMPcontent is a prerequisite for the manifestation of a negative inotropic effect of the nucleosides in ventricular cardiac muscle. Expand
Inhibitory adenosine receptors in the heart: characterization by ligand binding studies and effects on beta-adrenergic receptor stimulated adenylate cyclase and membrane protein phosphorylation.
The results suggest that the antiadrenergic effects of adenosine on cardiac tissue are mediated by a decrease in membrane protein phosphorylation signalled by activation of Ri-adenosine receptors. Expand
The effects of P1- and muscarinic-receptor agonists upon cAMP-dependent and independent inotropic responses of guinea-pig cardiac preparations.
L-PIA was able at high concentrations to inhibit the responses of left atria to the calcium channel opener Bay K 8644 and consistently attenuated the positive inotropes more effectively than carbachol, consistent with L-Pia being able to activate an additional negative inotropic mechanism thatcarbachol cannot. Expand
[Cardiac effects of adenosine. Mechanism of action, pathophysiologic and clinical significance].
  • M. Böhm
  • Chemistry, Medicine
  • Klinische Wochenschrift
  • 1987
Adenosine has negative chronotropic actions and prolongs AV conduction by an activation of potassium channels or an inhibition of the slow Ca2+ inward current (AV node). Expand