The potentiation of the action of adenosine on the guinea-pig heart

Hopkins, Sondra V.

doi:10.1016/0006-2952(73)90415-2

Cited by 59 publications

(25 citation statements)

References 10 publications

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“…This observation is in agreement with the results of previous workers who have shown that heart muscle accumulates radioactivity after exposure to labelled adenosine (Kolassa et al, 1970;Kraupp et al, 1966;Afonso et al, 1968 (Hopkins, 1973). This suggests that the three drugs do not prevent entry of adenosine into the tissue but rather that they inhibit the phosphorylation of adenosine and/or AMP and/or ADP.…”

Section: Discussionsupporting

confidence: 83%

The Accumulation of Adenosine in Rabbit Intestinal Muscle

Hulme

Weston

1974

British J Pharmacology

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Strips of longitudinal muscle from rabbit intestine accumulated radioactivity when exposed to [3H]‐adenosine. Accumulation of radioactivity was not sodium‐dependent or ouabain‐sensitive, but was reduced by cooling, zero glucose plus bubbling with N2, 2,4, dinitrophenol, dipyridamole, hexobendine and lidoflazine. After 7 min exposure to [3H]‐adenosine, the tissue was found to contain radioactive adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and adenosine itself in the approximate ratio 13: 6: 4: 1. In the presence of dipyridamole, hexobendine or lidoflazine (each 1 μm), the amounts of radioactive ATP, ADP, AMP and adenosine were reduced with the concentration of adenosine not significantly different from controls. It is concluded that energy‐dependent uptake of adenosine does not occur in the longitudinal muscle of rabbit intestine. Adenosine enters the tissue by a passive process and rapidly becomes phosphorylated giving rise to apparently high tissue: medium ratios. The drugs dipyridamole, hexobendine and lidoflazine appear to reduce the accumulation of radioactivity by preventing the formation of adenosine phosphate derivatives.

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Section: Discussionsupporting

confidence: 83%

The Accumulation of Adenosine in Rabbit Intestinal Muscle

Hulme

Weston

1974

British J Pharmacology

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“…It has been suggested that dipyridamole potentiates the action of adenosine by inhibiting adenosine uptake by erythrocytes (Pfleger et al, 1969) or tissue (Pfleger et al, 1969;Hopkins, 1973b;Kalsner, 1975). From the present results it seems likely that the brevity of the action of adenosine could be due to rapid uptake of adenosine by atrial tissue and that inhibition of this uptake by dilazep could result in augmentation and prolongation of the action of adenosine by increasing its effective concentration at the site of action.…”

Section: Discussionmentioning

confidence: 99%

“…The total amount of [3H]-adenosine taken up in 20 min was, at most, 6% of that in the medium and the concentration of [3H]-adenosine used was about 1/10 the concentration used in the contractility studies. Hopkins (1973b) and Kalsner (1975) were dubious from studies on atria and coronary arteries as to whether a 50% reduction of adenosine uptake ?ould cause 5 to 10 fold increase in the inhibitory action of adenosine. If this were the case, the potentiatior.…”

Section: Discussionmentioning

confidence: 99%

Potentiation by Dilazep of the Negative Inotropic Effect of Adenosine on Guinea‐pig Atria

Fujita

Ishida

Izumi

et al. 1980

British J Pharmacology

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IDilazep, a coronary dilator, has been reported to potentiate the negative inotropic and negative chronotropic responses of guinea-pig atria to adenosine. Studies were made on the mechanism of the potentiating action of dilazep with special reference to the degradation and uptake of adenosine. 2 The negative inotropic actions of adenosine and adenine nucleotides, such as ATP, ADP, AMP and cyclic AMP, on guinea-pig atria were selectively and dose-dependently augmented by dilazep at concentrations insufficient to produce any effect alone (0.01 to 1 tM). 4 Adenosine (10 pM to 10 mM) was degraded to inosine and hypoxanthine during incubation with atrial tissue; dilazep (0.1 to 10 pM) retarded the disappearance of adenosine and the formation of inosine and hypoxanthine. 5 These results suggest that dilazep potentiates the negative inotropic effect of adenosine on guineapig atria by preventing both its accumulation by atrial tissue and degradation by deaminase.

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“…The mode of action of this potentiation induced by dipyridamole has been explained by block of adenosine uptake, inhibition of adenosine deaminase or inhibition of phosphodiesterase (Schiimann 1958; Koss et al 1962; Pfleger and Schondorf 1969; Kolassa et al 1970;Hopkins 1973). However, it was also reported that dipyridamole potentiated not only adenosine but also norepineph rine, 5-HT or angiotensin in the renal circulation (Hashimoto et , al.…”

mentioning

confidence: 99%

Potentiation of the negative chronotropic and inotropic effects of adenosine by dipyridamole.

Chiba

1974

Tohoku J. Exp. Med.

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The potentiation of the action of adenosine on the guinea-pig heart

Cited by 59 publications

References 10 publications

The Accumulation of Adenosine in Rabbit Intestinal Muscle

The Accumulation of Adenosine in Rabbit Intestinal Muscle

Potentiation by Dilazep of the Negative Inotropic Effect of Adenosine on Guinea‐pig Atria

Potentiation of the negative chronotropic and inotropic effects of adenosine by dipyridamole.

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