Effect of prostaglandins I2 (prostacyclin) and F2 on function, energy metabolism, and calcium uptake in ischaemic/reperfused hearts

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Abstract
Objective: The aim was to examine the effect on cardiac function, energy metabolism, and calcium uptake of either prostaglandin I2 (PGI2, prostacyclin) or prostaglandin F2α (both 28.6 nM) on the response of isolated rat hearts to 25 min of total global ischaemia with or without 30 min reperfusion. Methods: Rat hearts were perfused by the Langendorff method and function assessed by left ventricular pressure. Energy metabolites were measured using enzymatic techniques and 45Ca2+ uptake determined by radioisotopic analysis. Results: Although there was no effect of either prostaglandin on contractile depression during ischaemia, both compounds accelerated the onset of and increased the magnitude of ischaemic contracture. High energy phosphate content at the end of the ischaemic period was not affected by prostaglandin treatment; however, tissue lactate levels were increased by PGI2, as was tissue calcium content. Under control conditions mean recovery of left ventricular developed pressure ranged from 66% to 83%. In the presence of PGI2 and PGF2α, recovery of developed pressure was reduced to 20% and 38% of preischaemic values, respectively. The reduced recovery in developed pressure was accompanied by an approximately threefold increase in diastolic pressure (pConclusions: Low concentrations of PGI2 and PGF2α can depress contractile recovery of the globally ischaemic heart through a mechanism associated with altered cellular energy metabolism and increased calcium accumulation. Cardiovascular Research 1993;27:396-402