The role of the carotid body chemoreceptors and carotid sinus baroreceptors in the control of cerebral blood vessels

Cholinergic Cerebral Vasodilatation: Lack of Involvement of Cranial Parasympathetic Nerves

“…Cranial nerves have been implicated in cerebral vasodilator responses by a number of investigators who have reported either changes in pial vessel size (Chorobski and Penfield, 1932;Cobb and Fine singer, 1932) or in blood flow of various cerebral structures upon stimulation of selected nerves (James et aI., 1969;D'Alecy and Rose, 1977;Pinard et aI., 1979), or who have observed alteration of the basic regulatory responses of the cerebral vascula ture following ablation of such nerves (James et aI., 1969;Ponte and Purves, 1974). However, this evi dence is counterbalanced by reports showing lack of effects of stimulation (Meyer et aI., 1971;Busija and Heistad, 198 1;Linder, 198 1) or ablation (Bates et aI., 1976;Heistad and Marcus, 1976;Hoff et aI., 1977;Traystman and Fitzgerald, 198 1) of the same cranial nerves on cerebrovascular regulation.…”

“…On the other hand, it has been suggested that glossopharyngeal and vagal innervation of chemo receptors may have a role as the afferent limb of a reflex mediating the cerebrovascular effects of CO2 (James et aI., 1969;Ponte and Purves, 1974), whereas cerebral vasodilator fibers in the seventh and/or other cranial nerves may serve as the efferent limb of such a reflex. Therefore, we also conducted ex periments in which the cerebrovascular effects of CO2 were tested before and after division of sinus, vagus, and aortic nerves in the neck, or intracranial division of nerves VII, VIII, IX, and XI.…”

Do vasomotor nerves significantly regulate cerebral blood flow?

“…Stimulation of the peripheral cut end of the 7th cranial or petrosal nerves causes pial dilation 26 and an increase in cerebral blood flow, 66 ' 72 an increase which does not appear to be CO 2 dependent. Electrical stimulation of the vagus, aortic, and sinus nerves causes pial vasodilation 64 and an increase in blood flow; 66 ' 73 physiological stimulation of chemoreceptors causes an increase in cerebral blood flow, 62 ' 63 a response abolished by sinus nerve section.…”

“…However, in most of the experiments, most of these factors can be excluded with some confidence, and there thus would be a strong case for the central representation of reflex pathways which regulate cerebral blood vessels in a fashion analogous to other vascular beds. These pathways would provide a structural basis for the responses of cerebral blood vessels to external stimuli such as cooling of the skin, 60 electrical stimulation of the sciatic nerve, 53 stimulation of pain receptors, 61 stimulation of the peripheral baro-and chemoreceptors, 62 ' M or electrical stimulation of the aortic and sinus nerves. 64 To summarize, I have suggested in this section that, although recent studies have clarified many VOL.…”

An increase in cerebral blood flow elicited by electrical stimulation of the solitary nucleus in rats with cervical cordotomy and vagotomy.

“…Purves and his colleagues (JAMES et al, 1969;PONTE and PURVES, 1974), and later, JAMES and MACDONELL (1975) claimed that the cardiovascular reflex mechanisms regulate the blood vessels of the brain. They concluded that inhibition of the arterial baroreceptors or activation of the peripheral chemoreceptors leads to an increase in cerebral blood flow.…”