Indomethacin-sensitive CO2 reactivity of cerebral arterioles is restored by vasodilator prostaglandin

Am J Physiol. 1994 Apr;266(4 Pt 2):H1332-8. doi: 10.1152/ajpheart.1994.266.4.H1332.


To investigate the role of vasodilator prostanoids in the CO2-induced relaxation of cerebral arterioles, the present study examined the effect of exogenous prostaglandin (PG) E2 and nonprostanoid vasodilators, adenosine and sodium nitroprusside, on the indomethacin-impaired pial arteriolar response to CO2 in newborn piglets. Reactivity of pial arterioles (52-131 microns diam) was determined using a closed cranial window with intravital microscopy. Cortical prostanoid synthesis was assessed by analyzing for select prostanoids in cerebrospinal fluid sampled from under the cranial window. Inhalation of 7% CO2 caused an elevation of cortical 6-keto-PGF1 alpha and thromboxane (Tx) B2 and increased pial arteriolar diameter by 34 +/- 5%. Two cyclooxygenase inhibitors, indomethacin (5 mg/kg i.v.) and ibuprofen (30 mg/kg i.v.), abolished the CO2-induced elevation of cortical prostanoids. Indomethacin, but not ibuprofen, blocked the CO2-induced increase in pial arteriolar diameter. The indomethacin-impaired vasodilator response to CO2 was restored when PGE2 (0.1-1 microM) was applied topically to the cortical surface. Adenosine (1-100 microM) and sodium nitroprusside (0.5 microM) only partially restored the vasodilator response to CO2. The data suggest that vasodilator prostanoids facilitate cerebrovascular relaxation to CO2 and may play a permissive role in the relaxation response of vascular smooth muscle. The fact that adenosine (adenosine 3',5'-cyclic monophosphate-mediated dilator) and sodium nitroprusside (guanosine 3',5'-cyclic monophosphate-mediated dilator), were partially effective suggests a role for those intracellular signaling pathways. We speculate that receptor activation of intracellular pathways may alter Ca2+ sensitivity of the contractile apparatus in such a way that the relaxation response to CO2 can occur.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Arterioles / drug effects
  • Carbon Dioxide / pharmacology*
  • Cerebrovascular Circulation / drug effects*
  • Ibuprofen / pharmacology
  • Indomethacin / pharmacology*
  • Pia Mater / blood supply
  • Prostaglandins / biosynthesis
  • Prostaglandins / pharmacology*
  • Swine
  • Vasodilator Agents / pharmacology


  • Prostaglandins
  • Vasodilator Agents
  • Carbon Dioxide
  • Ibuprofen
  • Indomethacin