In vivo effect of methylene blue on endothelium-dependent and endothelium-independent dilations of brain microvessels in mice.
Population
Mice (brain microvessels/arterioles observed by in vivo TV microscopy)
Comparison
Topical application of 10 M methylene blue for 7… vs Response to dilators without methylene blue…
Design
Preclinical
Authors
Discussion
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Implication
No clinical implications for cerebral vasodilation; leaves open mechanistic studies of guanylate cyclase inhibition in animal models.
Key Points
- To evaluate the in vivo effects of methylene blue on endothelium-dependent and endothelium-independent dilations in mouse cerebral arterioles.
- Observed surface arterioles of the mouse brain using in vivo television microscopy.
- Topically administered 10^-4 M methylene blue for 7 minutes prior to applying endothelium-dependent dilators (acetylcholine, bradykinin) and endothelium-independent dilators (sodium nitroprusside, 8-bromo-cGMP).
- Methylene blue significantly and reversibly depressed dilations elicited by acetylcholine, bradykinin, and sodium nitroprusside, showing the strongest inhibition against acetylcholine and the weakest against nitroprusside.
- Dilation induced by 8-bromo-cGMP remained unaltered by methylene blue pretreatment, supporting the role of guanylate cyclase inhibition in mediating the response.
Structured PICO
P
Population
Mice (brain microvessels/arterioles observed by in vivo TV microscopy)
I
Intervention
Topical application of 10(-4) M methylene blue for 7 minutes prior to application of dilators (acetylcholine, bradykinin, sodium nitroprusside, 8-bromo-cGMP)
C
Comparator
Response to dilators without methylene blue pretreatment
O
Outcome
Dilation of cerebral arteriolessurrogate
Methylene blue inhibits endothelium-dependent and some endothelium-independent vasodilation in cerebral microvessels in vivo, likely via guanylate cyclase inhibition.
Cite This Study
Watanabe et al. (1988) studied this question.