Accumulation of Prostacyclin in Rat Brain during Haemorrhagic Hypotension—Possible Role of PGI2in Autoregulation

The effect of haemorrhagic hypotension on the levels of prostaglandin E2 (PGE2), thromboxane B2 (TXB2), and 6-keto prostaglandin F1 alpha (6-keto-PGF1 alpha) in cortical tissue of rats was studied. Lightly anesthetized rats were subjected to steady-state hypotension for 15 min, with a mean arterial blood pressure of 80, 60, and 40 mm Hg, and compared to a control group of normotensive rats. No significant change was found in the levels of PGE2 and TXB2. The level of 6-keto-PGF1 alpha increased from 7.8 +/- 0.9 to 14.1 +/- 1.9 pg/mg protein (p less than 0.02) at 80 mm Hg. Our findings suggest that prostacyclin, which is a potent vasodilator, might play a role in setting the lower limit of the autoregulation range.