Effects of ischemia on cerebrovascular responses to N-methyl-D-aspartate in piglets

David W. Busija, Wei Meng, Ferenc Bari, P. Stephen McGough, Robert A. Errico, Joseph R. Tobin, Thomas M. Louis

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Abstract

We examined the effects of total global ischemia on cerebral arteriolar responses to N-methyl-D-aspartate (NMDA) in anesthetized newborn pigs. Arteriolar responses to 10-4 M NMDA were determined before and after 10 or 20 min of ischemia caused by increasing intracranial pressure. Before ischemia, NMDA dilated arterioles by 30 ± 5% (baseline = 88 ± 2 μm; n = 6). However, after 10 min of ischemia, arteriolar dilation was reduced to 10 ± 3% at 1 h (P < 0.05). At 2 and 4 h, NMDA-induced dilation was not different from preischemia values. Twenty minutes of ischemia had similar effects. Coadministration of 100 U/ml of superoxide dismutase did not restore arteriolar dilation to NMDA at i h after ischemia. Sodium nitroprusside dilated by 14 ± 3 and 40 ± 5% at 10-6 and 10-5 M before ischemia, respectively, and arteriolar responsiveness was not changed by ischemia (n = 6). Cortical nitric oxide synthase (NOS) activity, measured by the in vitro conversion of L-[14C]arginine to L-[14C]citrulline, was unaffected by ischemia (n = 12). We conclude that decreases in cerebral arteriolar responsiveness to NMDA are not due to impairment of NOS activity, enhanced degradation or chelation of nitric oxide (NO), or reduced vascular smooth muscle responsiveness to NO.

Original languageEnglish
Pages (from-to)H1225-H1230
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume270
Issue number4 39-4
Publication statusPublished - May 13 1996

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Keywords

  • amino acids
  • arterioles
  • cerebral blood vessels
  • indomethacin
  • nitric oxide synthase
  • oxygen radicals
  • prostaglandins

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

Busija, D. W., Meng, W., Bari, F., Stephen McGough, P., Errico, R. A., Tobin, J. R., & Louis, T. M. (1996). Effects of ischemia on cerebrovascular responses to N-methyl-D-aspartate in piglets. American Journal of Physiology - Heart and Circulatory Physiology, 270(4 39-4), H1225-H1230.