Vascular desensitisation--possible role of prostaglandins.

Prolonged exposure to noradrenaline (NA) brings about an increase in the release of prostaglandin (PG)-like material from rat aortic strip. The release is greater with oxymetazoline while methoxamine decreases it. These effects are blocked by yohimbine and prazosin respectively. Pretreatment with 6·0HDA or reserpine diminishes the release of PG-like material. Barium chloride. a non-specific spasmogen, does not affect the release significantly. It appears therefore that the source of PG-like material is presynaptic and that its release mechanism is linked to an alpha2 (00::.) adrenoceptor. It is propolled that this release of PGlike material contributes to the development of desensitisation in vascular tissue.