Effects of topical adenosine analogs and forskolin on rat pial arterioles in vivo.
We utilized the closed window technique to study the in vivo responses of rat pial arterioles to superfused adenosine agonists. Adenosine and its analogs dilated pial arterioles and exhibited the following order of potency: 5'N-ethylcarboxamide adenosine (NECA) greater than 2-chloroadenosine (2-CADO) greater than adenosine = R-N6-phenylisopropyladenosine (R-PIA) = S-PIA greater than N6-cyclohexyladenosine (CHA). This potency profile suggests that cerebral vasodilation is mediated through the A2 receptor. Forskolin (10(-9) M) potentiated the vasodilation caused by 10(-6) M NECA, thus implicating adenylate cyclase activation during NECA-induced vasodilation and providing further support for involvement of the A2 receptor.
Ibayashi
S
S
Department of Neurological Surgery, University of Washington School of Medicine, Harborview Medical Center, Seattle 98104.
Ngai
A C
AC
Meno
J R
JR
Winn
H R
HR
D015762:2-Chloroadenosine / Q000494:pharmacology; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D019830:Adenosine-5'-(N-ethylcarboxamide); D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology*; D008297:Male; D010660:Phenylisopropyladenosine / Q000494:pharmacology; D010841:Pia Mater / Q000098:blood supply*; D051381:Rats; D011919:Rats, Inbred Strains; D014664:Vasodilation / Q000187:drug effects*
D015762:2-Chloroadenosine; D005576:Colforsin; D010660:Phenylisopropyladenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); C027513:N(6)-cyclohexyladenosine; D000241:Adenosine