Effects of vasodilator stimuli on resistance of large and small cerebral vessels

K. Tamaki, W. Mayhan, D. Heistad

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Abstract

We have examined effects of vasodilator stimuli on segmental resistance in the cerebral circulation. Our hypothesis was that resistance of large arteries, as well as small vessels, contributes to cerebral vascular responses to vasodilator stimuli. We measured cerebral blood flow with microspheres in anesthetized rabbits and measured pressure in pial arteries ~100 μm diameter using a servo-null method. These values were used to calculate resistance of large arteries (> 100 μm diameter) and small vessels (< 100 μm diameter). Under control conditions, resistance of large arteries accounted for one-third to one-half of total cerebral vascular resistance. Intracarotid infusion of acetylcholine (1 μg/min) reduced large arterial resistance by 69% and small vessel resistance by 58%. Adenosine also produced marked reductions in resistance of both large and small cerebral vessels. In contrast, seizures reduced large arterial resistance by 50% and small vessel resistance by 85%. Pial arterial pressure, which depends on the ratio of large and small vessel resistance, increased during infusion of acetylcholine and adenosine, but decreased during seizures. We conclude that 1) both large and small cerebral vessels are responsive to acetylcholine and adenosine, and 2) seizures produce preferential reduction in resistance of small vessels.

Original languageEnglish (US)
Pages (from-to)20/6
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume251
Issue number6
StatePublished - Dec 1 1986

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ASJC Scopus subject areas

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

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