In Vitro Production of Prostaglandins by Isolated Aorta Strips of Normotensive and Hypertensive Rats

Abstract

When suspended in oxygenated Krebs solution at 37 °C, strips derived from thoracic aortae of spontaneously hypertensive rats maintain their initial intrinsic tone and release prostaglandin-like material in the suspending medium, while similar preparations from normal Wistar rats relax progressively and produce significantly smaller amounts of prostaglandins.Indomethacin, a potent antagonist of prostaglandin synthesis, has two major effects: it favors the relaxation of both strips of hypertensive rats and of normal rats; and it inhibits the accumulation of prostaglandin-like material in the suspending medium, as evaluated with a specific and sensitive biological assay (rat stomach strip or chick rectum).Carotid and femoral arteries taken from the same animals show similar differences as the aorta strips, with regard to the production of prostaglandin-like material. The generation of prostaglandin is markedly decreased by the absence of O₂, while it is unaffected by the absence of the extracellular Ca²⁺. It is proposed that the absence of relaxation of aorta strips taken from hypertensive, compared to normal rats, is due to increased intramural synthesis and release of prostaglandins.