期刊
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
卷 291, 期 3, 页码 R728-R735出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpregu.00757.2005
关键词
carbon monoxide; cerebral circulation; cyclooxygenase; epoxygenase; neurovascular coupling; nitric oxide
类别
资金
- NHLBI NIH HHS [HL-59996, P01 HL059996] Funding Source: Medline
Nitric oxide (NO) has been implicated in mediation of cerebral vasodilation during neuronal activation and, specifically, in pharmacological activation of N-methyl-D-aspartate (NMDA) and kainate receptors. Possible mediators of cerebral vasodilation to alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) have not been well studied in mature brain, although heme oxygenase (HO) activity has been implicated in newborn pigs. In anesthetized rats, 5 min of topical superfusion of 30 and 100 mu M AMPA on the cortical surface through a closed cranial window resulted in increases in pial arteriolar diameter. The dilatory response to AMPA was not inhibited by superfusion of an NO synthase inhibitor, a cyclooxygenase-2 inhibitor, or a cytochrome P-450 epoxygenase inhibitor, all of which have been shown to inhibit the cortical blood flow response to sensory activation. However, the 48 +/- 13% dilation to 100 mu M AMPA was attenuated 56 - 71% by superfusion of the adenosine A(2A) receptor antagonist ZM-241385, the A(2B) receptor antagonist alloxazine, and the HO inhibitor chromium mesoporphyrin. Combination of the latter three inhibitors did not attenuate the dilator response more than the individual inhibitors, whereas an AMPA receptor antagonist fully blocked the vasodilation to AMPA. These results indicate that cortical pial arteriolar dilation to AMPA does not require activation of NO synthase, cyclooxygenase-2, or cytochrome P-450 epoxygenase but does depend on activation of adenosine A(2A) and A(2B) receptors. In addition, CO derived from HO appears to play a role in the vascular response to AMPA receptor activation in mature brain by a mechanism that is not additive with that of adenosine receptor activation.
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