VIP-ergic and cholinergic innervations in internal carotid arteries of the cat and rat.
Using immunohistochemical methods, choline acetyltransferase and vasoactive intestinal polypeptide immunoreactive (ChAT-I and VIP-I) fine fibers with varicosity-like structures were observed in the rat and cat cerebral arteries. Acetylcholine (ACh) induced dual responses in endothelium-intact internal carotid arteries of the cat; it induced vasodilation at low concentrations and constrictions at high concentrations (greater than 10(-6) M). ACh induced contraction exclusively in endothelium-rubbed preparations. Atropine (10(-7) M) blocked ACh-induced constriction and dilatation. ACh-induced vasodilation was potentiated by M & B 22,948 (2 x 10(-5) M), a selective cyclic GMP phosphodiesterase inhibitor. Vasoconstriction induced by ACh was inhibited by neomycin (3 x 10(-3) M), an inositol phosphate synthesis inhibitor, which did not affect the neuropeptide Y-induced contraction. VIP-induced dilation of the cat internal carotid arteries was not affected by removing the endothelial layer, but was blocked by VIP receptor antagonist ([Ac-Tyr1, D-Phe2]-GRF 1-29 amide) and potentiated by cilostazol (2 x 10(-5) M), a selective cyclic AMP phosphodiesterase inhibitor. These results are consistent with previous findings that cerebral blood vessels receive cholinergic and VIP-ergic innervations, and that ACh-induced endothelium-dependent vasodilation is mediated by cyclic GMP synthesis, and that VIP-induced endothelium-independent vasodilation is mediated by cyclic AMP synthesis. The present study, however, demonstrates for the first time the presence of varicosity-like structure associated with ChAT-I fibers, suggesting the presence of cholinergic nerve terminals and that ACh-induced cerebral vasoconstriction is mediated by phosphatidyl-inositide turnover.
Miao
F J
FJ
Department of Pharmacology, Southern Illinois University, School of Medicine, Springfield 62794-9230.
Lee
T J
TJ
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002339:Carotid Arteries / Q000294:innervation*; D002415:Cats; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009478:Neuropeptide Y / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013194:Staining and Labeling; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology / Q000502:physiology*
D009478:Neuropeptide Y; D014660:Vasoactive Intestinal Peptide; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine