PROSTAGLANDIN INACTIVATION IN GUINEA-PIG LUNG AND ITS INHIBITION

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Abstract
1 Several compounds were tested for their ability to inhibit prostaglandin metabolism in guinea-pig lungs. 2 In isolated perfused lungs polyphoretin phosphate (PPP) inhibited prostaglandin metabolism being active at concentrations greater than 100 ng/ml and having an ID50 of 2.15 μg/ml against prostaglandin E2 metabolism and 1.55 μg/ml against prostaglandin F2α metabolism. 3 At these doses no antagonism of the actions of prostaglandins was seen. 4 Diphloretin phosphate (DPP) was more active on a weight for weight basis and inhibition of inactivation of prostaglandins was seen at concentrations greater than 10 ng/ml, the ID50 being 0.54 μg/ml against both prostaglandins E2 and F2α. 5 At concentrations greater than 5 μg/ml DPP antagonized the actions of prostaglandin F2∞. 6 The sulphydryl-binders N-ethyl maleimide (NEM) and sodium p-chloromercuriphenyl sulphonate (PCMS) also inhibited prostaglandin inactivation by guinea-pig isolated lungs. 7 All four compounds inhibited prostaglandin metabolism by a crude enzyme preparation from guinea-pig lungs.