Cholinergic Cerebral Vasodilatation: Lack of Involvement of Cranial Parasympathetic Nerves

Abstract

Cerebral blood flow (CBF) was estimated by measurement of internal carotid blood flow (ICBF) and sagittal sinus blood flow (SSBF) in mechanically ventilated rabbits under 70% N2O/30% O2. Electrical stimulation of cranial nerves III, VII, IX, or X, with stimulus parameters adequate to excite other visceromotor outflows of these nerves, failed to elicit change in CBF. Combined bilateral section of nerves VII, VIII, IX, X, and XI had no effect on the reactivity of CBF to CO2, nor did the sectioning of these nerves affect the increases in CBF induced by physostigmine. Division of the sinus and aortic nerves and of the vagi in the neck failed to change CO2 reactivity, even though normocapnic CBF was reduced. Pentobarbital blocked the increase in CBF produced by physostigmine, but had no effect on that produced by pilocarpine. The results indicate that cranial parasympathetic nerves do not contain cerebral vasodilator fibers, and that they are not the source of acetylcholine which is presumably involved in CBF regulation.

Relative Contribution of Endothelium-Derived Relaxation Factor to Vascular Tone in the Systemic, Pulmonary, and Cerebral Circulations of Piglets

“…One of the unique features of our experimen tal protocol is the ability to monitor cerebral, systemic, and pulmonary blood flow and per fusion pressure simultaneously and contin uously. The technique we have developed to measure cerebral blood flow, using a flow probe on the common carotid artery after liga tion of the ipsilateral external carotid circula tion, was adapted from the work of Gootman et al [13,14] and Scremin et al [15,16]. Pig lets are a particularly useful species in which to attempt these measurements, as their cere bral venous anatomy, arterial anatomy, and lack of a significant rete mirabile all aid in the correlation of ICBF and CBF.…”

“…Briefly, a modification of the method of Gootman and Klein [13,14] and Scremin et al [15,16] was used. Two sepa rate dissections were made in the right neck region.…”

Light and electron microscopic immunocytochemical analysis of the neurovascular relationships of choline acetyltransferase and vasoactive intestinal polypeptide nerve terminals in the rat cerebral cortex

“…Similarly, physiological evidence has accumulated over the last years which indicate a role for brain intrinsic ACh neurons in cerebral (Scremin et al, 1983(Scremin et al, , 1988) and more specifically in cortical vasodilatation following stimulation of various brain areas including the basal forebrain (Biesold et al, 1989;Lacombe et al, 1989) and the fastigial nucleus of the cerebellum Nakai et al, 1982). This central cholinergic regulation of the cortical microvasculature depends on the release of ACh (Kurosawa et al, 19891, appears uncoupled to energy metabolism (Kimura et al, 1990;Nakai et al, 1983) and is mediated by specific muscarinic and/or nicotinic receptors (ArneriC, 1989;Biesold et al, 1989;Dauphin et al, 1991;Iadecola et al, 1986).…”

Brain regional distribution of physostigmine and its relation to cerebral blood flow following intravenous administration in rats

“…pulse injection is attended, after 2-3 min, by an increase in internal carotid artery blood flow, a vessel that supplies almost exclusively the brain in this species (Scremin et al, 1982a). The effect peaks in 6 min (Scremin et al, 1983). Half-life of disappearance of physostigmine vasodilatation in the parietal cerebral cortex of the rat, measured locally by hydrogen gas clearance, is approximately 15 min (Scremin and Scremin, 1986).…”