Influence of electrically induced tachyarrhythmia on the release of cyclic AMP and PGE in canine coronary sinus blood and on the level of cyclic AMP in myocardial tissue.
In anaesthetized open-chest dogs tachyarrhythmia (TA) was electrically induced by above-threshold stimuli via the right ventricle. During TA a significant increase in the release of PGE and cyclic AMP of 20% and 40% of the control levels, respectively, was observed in the canine coronary sinus blood (CSB), whereas the level of PGF2 alpha remained nearly unchanged under these conditions. The efflux of cyclic AMP corresponded with a concomitant increase in the left ventricular tissue level of this nucleotide by 59% during TA. Pretreatment with the beta-adrenergic blocking agent propranolol (1.0 mg/kg i.v.) prevented the TA induced changes in the level of PGE as well as cyclic AMP in the CSB and in the tissue levels of cyclic AMP. Propranolol alone was without any effect on the efflux of cyclic AMP, but decreased significantly the efflux of PGE by 32%. There was an increase in the activity of phosphorylase a in the myocardial tissue from 10% to 20% of the total (a + b) activity of this enzyme during TA, which could be abolished by propranolol pretreatment. The results suggest possible interrelationships between catecholamines, cyclic AMP and PGE.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D000242:Cyclic AMP / Q000097:blood*; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D006321:Heart / Q000187:drug effects; D006352:Heart Ventricles; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D011458:Prostaglandins E / Q000097:blood*; D013610:Tachycardia / Q000097:blood*
D007773:Lactates; D011458:Prostaglandins E; D010725:Phosphocreatine; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D011433:Propranolol; D000242:Cyclic AMP