Interactions of isoprenaline and prostaglandin E2 with respect to myocardial contractile force, coronary vascular resistance and myocardial oxygen consumption in guinea-pig isolated hearts.
Left ventricular pressure (LVP), left ventricular pressure derivative (LV dp/dtmax), coronary vascular resistance (CVR) and myocardial oxygen consumption (Qo2) were measured simultaneously in isolated, electrically driven hearts of guinea-pigs at constant perfusion rate. 2 LVP, LV dp/dtmax, CVR and Qo2 were greatly decreased by either the addition of prostaglandin E2 (50 ng/ml) to the perfusion fluid or pretreatment of the animals with reserpine. 3 Isoprenaline (0.5 nM to 100 nM) induced increases in LVP, LV dp/dtmax and Qo2. In the presence of prostaglandin E2, there was a parallel shift of the isoprenaline concentration-response curve for LVP and LV dp/dtmax. This effect was not seen, after the animals had been treated with reserpine. 4 Qo2 was also decreased by prostaglandin E2 only in non-reserpine treated animals. 5 CVR was diminished by isoprenaline in the untreated group. However, there was increase in CVR, when isoprenaline was added to either prostaglandin E2 or reserpine-pretreated hearts which was enhanced in the reserpine plus prostaglandin E2-treated group (P less than 0.01). 6 The results give evidence for different actions of prostaglandin E2 on isoprenaline concentration-response curves for LVP, LV dp/dtmax and CVR.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006168:Guinea Pigs; D007213:Indomethacin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects*; D011458:Prostaglandins E / Q000494:pharmacology*; D012110:Reserpine / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects*
D011458:Prostaglandins E; D012110:Reserpine; D007545:Isoproterenol; D009638:Norepinephrine; D007213:Indomethacin