Heterogeneity of neurogenic responses in intra- and extrameningeal arteries of dogs.
1. Neurogenic responses to transmural electrical stimulation were examined in endothelium-denuded extrameningeal (vertebral and carotid) and intrameningeal (spinal, basilar and middle cerebral) arteries isolated from dogs. 2. In the extrameningeal arteries, transmural electrical stimulation produced a phasic contraction. This contraction was abolished by tetrodotoxin, prazosin and guanethidine. However, alpha,beta-methylene ATP and NG-nitro-L-arginine (L-NOARG) had no significant effect on the contractile responses. 3. In the intrameningeal arteries, the neurogenic responses to electrical stimulation were composed of a transient contraction and relaxation. The transient contraction was selectively inhibited by guanethidine L-NOARG abolished the relaxation but not the contraction induced by electrical stimulation. Prazosin had no effect on either neurogenic response. 4. Noradrenaline produced a large contraction in the extrameningeal arteries which was selectively inhibited by prazosin. alpha,beta-Methylene ATP produced neither contraction nor inhibition of the response to noradrenaline in the extrameningeal arteries. 5. In the intrameningeal arteries, alpha,beta-methylene ATP produced a greater contraction than noradrenaline. The response to alpha,beta-methylene ATP was selectively abolished by desensitization of P2x-purinoceptors with alpha,beta-methylene ATP itself. The contractile response to noradrenaline was inhibited by rauwolscine but not by prazosin. 6. ATP produced endothelium-dependent relaxations in the extrameningeal and intrameningeal arteries, which were attenuated by endothelium removal. 7. NADPH diaphorase-positive fibres were dense in the middle cerebral and basilar arteries but rare or absent in the spinal artery. In the extrameningeal arteries diaphorase-positive traces were observed in the vasa vasorum. 8. The present findings indicate that the neurogenic responses of intrameningeal arteries of dogs are composed of NO-ergic and sympathetic purinergic components, while the extrameningeal arteries tested produced only sympathetic adrenergic responses, suggesting that regional heterogeneity may be associated with a sudden transition in innervation and receptor expression at the meninx.
Kohno
Y
Y
Department of Otorhinolaryngology, Fukui Medical School, Japan.
Saito
T
T
Saito
H
H
Aoyama
H
H
Nojyo
Y
Y
Kigoshi
S
S
Muramatsu
I
I
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001158:Arteries / Q000187:drug effects / Q000294:innervation*; D001488:Basilar Artery / Q000294:innervation; D002339:Carotid Arteries / Q000294:innervation; D002536:Cerebral Arteries / Q000294:innervation; D004285:Dogs; D004558:Electric Stimulation; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000294:innervation; D009252:NADPH Dehydrogenase / Q000032:analysis; D009412:Nerve Fibers / Q000201:enzymology; D019335:Nitroarginine; D009638:Norepinephrine / Q000494:pharmacology; D014711:Vertebral Artery / Q000294:innervation
D000316:Adrenergic alpha-Agonists; D019335:Nitroarginine; D000255:Adenosine Triphosphate; D001120:Arginine; D009252:NADPH Dehydrogenase; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine