Prostacyclin release in experimental diabetes: effects of evening primrose oil

Alterations in release of endothelium-derived vasomotor agents could underlie microvascular and neuropathic complications in diabetes. This study examined release of the potent vasodilator prostacyclin, measured as immunoreactive 6-keto prostaglandin F1 alpha, from rat lung, kidney and peripheral nerve. Tissues were taken from control and streptozotocin-diabetic rats which had been treated for 8 weeks with either evening primrose oil (EPO) or, as a control for lipid intake, coconut oil (CO). Lung and kidney slices were incubated in the presence of acetylcholine (ACh), the calcium ionophore 4-Br-A23187, arachidonic acid (AA) or without agonist (basal). Segments of sciatic nerve, with their epineuria punctured, were incubated with or without 4-Br-A23187. Basal prostacyclin release from the lung was significantly higher in rats treated with EPO irrespective of diabetic state (increased by 60% in controls and by 77% in diabetics). Levels were reduced in CO-diabetics compared to EPO-controls (53% reduction) and CO-controls (30% reduction), although this did not reach statistical significance in the latter. Basal prostacyclin release was also significantly reduced in the kidney from CO-diabetics (40% reduction compared to CO-controls and 56% reduction compared to EPO-controls). In the presence of AA, lung prostacyclin release was significantly lower in CO-diabetic rats compared to all other groups (40% reduction compared to EPO-diabetics and 60% compared to both control groups) but there were no differences in renal release between any group. Prostacyclin release by nerves from CO-diabetic rats was significantly reduced (by 91-93%) compared to all other groups.(ABSTRACT TRUNCATED AT 250 WORDS)