PROSTANOIDS DETERMINE THE RANGE OF CEREBRAL BLOOD-FLOW AUTOREGULATION OF NEWBORN PIGLETS

To assess whether prostanoids have a role in setting the blood pressure limits of cerebral blood flow autoregulation in newborn animals, we measured cerebral blood flow and prostanoid concentrations in blood from the sagittal sinus over a wide range of mean systemic blood pressures (17-117 mm Hg) in eight newborn piglets treated with 30 mg/kg i.v. ibuprofen and in eight vehicle-treated piglets. Blood pressure was adjusted by inflating balloon-tipped catheters placed at the aortic isthmus and root to induce hypertension and hypotension, respectively, 80 minutes apart in each piglet Cerebral blood flow and concentrations of prostaglandins E and F2α, 6-keto-prostaglandin Flα, and thromboxane B2 in blood from the sagittal sinus and left subclavian artery were measured 20 minutes before (baseline) and during each blood pressure adjustment In vehicle-treated piglets, cerebral blood flow was constant at blood pressures between 50 and 90 mm Hg (r=0.06, p=0.85). When blood pressure was reduced to <50 mm Hg, thromboxane B2 concentration in the sagittal sinus increased by 597±42% and concentrations of the prostaglandins increased by an average of 308±45% (p<0.05). When blood pressure was raised to >90 mm Hg, concentrations of the prostaglandins increased by an average of 46±11%, with no change in the concentration of thromboxane Bj. Treatment with ibuprofen reduced the baseline concentrations of all prostanoids and prevented their changing during hypotension and hypertension. This inhibition of prostanoid synthesis was associated with a widened range of cerebral blood flow autoregulation (blood pressures between 35 and 117 mm Hg) (r=0.26, p=0.21). In conclusion, prostaglandins and thromboxane contribute significantly to determining the blood pressure limits of cerebral blood flow autoregulation of newborn animals. © 1990 American Heart Association, Inc.