Influence of pressure, flow rate, and pulsatility on release of 6-keto-PGF1 alpha and thromboxane B2 in ex vivo-perfused canine veins.

The influence of pressure, flow, and pulsatility on the release of prostacyclin (measured as 6-keto-PGF1 alpha) and thromboxane (measured as TxB2) was assessed in canine jugular veins perfused ex vivo with Hanks' balanced salt solution for five consecutive 15-minute periods. Control segments were perfused at 7 mm Hg with nonpulsatile flow at a rate of 90 ml/min, whereas experimental segments were perfused with pulsatile flow as well as nonpulsatile flow at pressures of 50 or 100 mm Hg and flow rates of 60 or 130 ml/min. Prostacyclin release from control segments during the first 15-minute period was 49.5 +/- 7.4 pg/mm2/15 min, which declined to 13.9 +/- 2.5 pg/mm2/15 min after 60 minutes (p less than 0.002). Arachidonic acid stimulation during the last 15-minute perfusion period increased the release to 56.1 +/- 9.4 pg/mm2/15 min (p less than 0.002). Thromboxane release from control segments was initially 4.4 +/- 1.2 pg/mm2/15 min, which declined to 0.8 +/- 0.2 pg/mm2/15 min after 60 minutes (p less than 0.002), and subsequently increased with arachidonic acid stimulation to 1.3 +/- 0.1 pg/mm2/15 min (p less than 0.01). In contrast to control perfusion conditions, changes in nonpulsatile flow rates did not affect prostacyclin release, whereas thromboxane release was lower when perfused at 60 ml/min. Pressures of 50 and 100 mm Hg increased the initial release of prostacyclin. Similarly, pulsatile flow enhanced prostacyclin release at both low and high pressures, being more pronounced with the latter.(ABSTRACT TRUNCATED AT 250 WORDS)