Carbon monoxide and cerebral microvascular tone in newborn pigs.

Abstract

The present study addresses the hypothesis that CO produced from endogenous heme oxygenase (HO) can dilate newborn cerebral arterioles. HO-2 protein was highly expressed in large and small blood vessels, as well as parenchyma, of newborn pig cerebrum. Topically applied CO dose-dependently dilated piglet pial arterioles in vivo over the range 10(-11)-10(-9) M (maximal response). CO-induced cerebrovascular dilation was abolished by treatment with the Ca2+-activated K+ channel inhibitors tetraethylammonium chloride and iberiotoxin. The HO substrate heme-L-lysinate also produced tetraethylammonium-inhibitable, dose-dependent dilation from 5 x 10(-8) to 5 x 10(-7) M (maximal). The HO inhibitor chromium mesoporphyrin blocked dilation of pial arterioles in response to heme-L-lysinate. In addition to inhibiting dilation to heme-L-lysinate, chromium mesoporphyrin also blocked pial arteriolar dilations in response to hypoxia but did not alter responses to hypercapnia or isoproterenol. We conclude that CO dilates pial arterioles via activation of Ca2+-activated K+ channels and that endogenous HO-2 potentially can produce sufficient CO to produce the dilation.

• Authors: C W Leffler, A Nasjletti, C Yu, R A Johnson, A L Fedinec, N Walker
• Journal: The American journal of physiology (Am J Physiol) Vol. 276 Issue 5 Pg. H1641-6 (05 1999) ISSN: 0002-9513 [Print] United States
• PMID: 10330249 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Mesoporphyrins
• Potassium Channels
• Vasodilator Agents
• heme lysinate
• Chromium
• Nitroarginine
• Heme
• mesoporphyrin IX
• Tetraethylammonium
• Carbon Monoxide
• Cyclic AMP
• Heme Oxygenase (Decyclizing)
• heme oxygenase-2
• Cyclic GMP
• Lysine

Topics

• Animals
• Animals, Newborn
• Brain (blood supply, enzymology)
• Brain Chemistry (physiology)
• Carbon Monoxide (pharmacology)
• Cerebral Arteries (drug effects, physiology)
• Cerebrovascular Circulation (drug effects)
• Chromium (pharmacology)
• Cyclic AMP (metabolism)
• Cyclic GMP (metabolism)
• Dose-Response Relationship, Drug
• Heme (analogs & derivatives, pharmacology)
• Heme Oxygenase (Decyclizing) (metabolism)
• Lysine (analogs & derivatives, pharmacology)
• Mesoporphyrins (pharmacology)
• Microcirculation (physiology)
• Nitroarginine (pharmacology)
• Pia Mater (blood supply)
• Potassium Channels (physiology)
• Swine
• Tetraethylammonium (pharmacology)
• Vasodilation (drug effects)
• Vasodilator Agents (pharmacology)