In the middle cerebral artery (MCA), the presence of nitric oxide (NO) is responsible for maintaining a more dilated state than in its absence during increases in extracellular K + and osmolality. The purpose of the present study was to determine whether the involvement of NO was due to (a) a direct effect of the K + /osmolality ( K hyper ) on the endothelium or (b) a ‘permissive’ role of NO. MCAs (approximately 210 μm o.d.) were isolated, cannulated with glass micropipettes, and pressurized to 85 mmHg. When K + (KCl) in the extraluminal bath was increased to 21 mM, the diameter increased by 15–20% with the magnitude of dilation diminishing with further increases in K hyper . The addition of N G -nitro- l -arginine methyl ester ( l -NAME, 10 −5 mM), an inhibitor of nitric oxide synthase, had no significant effect on dilations at lower K hyper concentrations but constricted the arteries relative to the control at 51, 66, and 81 mM K hyper . In the presence of l -NAME, the addition of an exogenous NO donor, S -nitroso- N -acetylpenicillamine (SNAP, 10 −8 M) or an analog of cGMP, 8-bromo-cGMP (6×10 −5 M), tended to restore the response of K hyper to near the original response. We conclude that the basal release of NO from the endothelium plays a permissive role in the K hyper -induced response.
Brain Research – Elsevier
Published: Jan 19, 2001
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera