Morphological examination of the adventitia of cerebral blood vessels reveals nerves which exhibit two distinct profiles. When fixed with KMnO*, the terminal axons contain either small granular vesicles or agranular vesicles. The granular vesicle-containing nerves (GVN) are of sympathetic origin, whereas the agranular vesicle-containing nerves (AVN) apparently are not sympathetic, since they remain after sympathetic denervation of the blood vessels (Iwayama et al., 1970;Owman et al., 1974;Lee et al., 1980). Previous work has established that the GVN mediate vasoconstriction (Lee et al., 1976, and although it has been suggested that the AVN mediate vasodilation, this ideas has not been rigorously examined.Cerebral arteries of the cat are innervated by both GVN and AVN. Curiously, when studied in vitro these arteries dilate only when subjected to transmural nerve stimulation (TNS), a situation unlike that in rabbit cerebral arteries (Lee et aL, 1976(Lee et aL, , 1978. The cat blood vessels therefore were utilized in the present studies in order to evaluate the relationship between vasodilation and the AVN. The results indicate a strong correlation between the degree of TNS-induced vasodilation and AVN in the cerebral vessels. In addition, the relative distribution of the AVN and GVN in cerebral arteries of different sizes was compared in quest of possible regional variation of the vasoconstrictor and dilator innervation. MethodsAdult cats (2-3 kg) of either sex were anesthetized with pentobarbital (40 mg/kg, i.p.) and exsanguinated. The entire brain with blood vessels attached was rapidly removed and placed in ice-cold (4°C) normal saline. Basilar arteries (BA) (10 mm long, outer diamter 0.4-0.5 mm), middle cerebral arteries (MA) (5 mm long, outer diameter 0.4-0.6 mm), anterior cerebral arteries (AA) (5 mm long, outer diameter 0.2-0.4 mm) immediately adjacent to the circle of Willis, and small branches of middle cerebral arteries (SMA) (5 mm long, outer diameter 0.1-0.2 mm) from the surface area of sylvian sulcus were excised with the aid of a dissecting microscope. Electron MicroscopyFreshly dissected arterial segments were fixed in ice-cold 2% KMnO< in Millonig phosphate buffer (pH 7.4, 490 mOsmol). Preparation of the fixative, fixation, dehydration, and final embedding of the specimens were carried out as previously described . All blocks were oriented for transverse sectioning of the arteries. Ultrathin crosssections of the arteries were obtained with an LKB microtome fitted with a diamond knife. The sections were mounted on slot grids coated with Formvar and were stained with 0.4% uranylacetate and
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.