The relative importance of peripheral vs. central chemoreceptors in causing apnea/unstable breathing during sleep is unresolved. This has never been tested in an unanesthetized preparation with intact carotid bodies. We studied three unanesthetized dogs during normal sleep in a preparation in which intact carotid body chemoreceptors could be reversibly isolated from the systemic circulation and...

A description is given of crustacean chemosensory systems and the neurophysiological procedures used to study them. Their response properties and tuning characteristics are discussed. A review is then provided of specific crustacean chemoreceptors that are stimulated selectively by either purine nucleotides, taurine, glutamate, or glycine, all of which have neuroactive properties in internal ti...

Galanin is present in neurons in the brain that are important in the control of arterial pressure and intracisternal administration of galanin evokes hypotension, but the site of action is unknown. In urethane-anaesthetised, vagotomised mechanically ventilated Sprague Dawley rats (N=34), we investigated the effects of microinjecting galanin (1mM, 50nL, 50pmol) into the rostral ventrolateral med...

The hypothesis that, in neuromuscular and chest wall diseases, improvement in central respiratory drive explains the effects of night-time ventilation on diurnal gas exchanges was tested. The effects at 6 months, 1, 2 and 3 yrs of intermittent positive pressure ventilation (IPPV) on arterial blood gas tension, pulmonary function, muscle strength, sleep parameters, respiratory parameters during ...

HYPERCAPNIA, largely through the direct influence of CO2 on proton production, but possibly also via a direct effect of molecular CO2, is the primary chemical stimulus for alveolar ventilation. Small deviations in arterial CO2 in either direction elicit integrated cardiorespiratory reflexes that quickly restore CO2 levels in various tissue and cellular compartments, thereby providing the body w...

Voluntary apnea activates the central and peripheral chemoreceptors, leading to a rise in sympathetic nerve activity and limb vasoconstriction (i.e., brachial blood flow velocity and forearm cutaneous vascular conductance decrease to a similar extent). Whether peripheral and/or central chemoreceptors contribute to the cutaneous vasoconstrictor response remains unknown. We performed three separa...

In contrast to Escherichia coli, a model organism for chemotaxis that has 5 chemoreceptors and a single chemosensory pathway, Pseudomonas aeruginosa PAO1 has a much more complex chemosensory network, which consists of 26 chemoreceptors feeding into four chemosensory pathways. While several chemoreceptors were rigorously linked to specific pathways in a series of experimental studies, for most o...

were the carotid chemoreceptors also excluded from the circulation of the remainder of the body? Dr. Levine: In the head perfused animal preparation (Ic third preparation), both the carotid chemoreceptors and the brain were excluded from the circulation to the remainder of the body. the effect of acute cord transection on blood pressure? Dr. Levine: My dogs were anesthetized with chioralose (no...

Brainstem central chemoreceptors are critical to the hypercapnic ventilatory response, but their location and identity are poorly understood. When studied in vitro, serotonin-synthesizing (5-HT) neurons within the rat medullary raphé are intrinsically stimulated by CO2/acidosis. The contributions of these neurons to central chemosensitivity in vivo, however, are controversial. Lacking is docume...

CGS-21680 (CGS), a highly selective adenosine A2a receptor agonist, may excite the fetal carotid bodies. This study was designed to determine 1) whether CGS stimulates fetal breathing and 2) whether sinoaortic denervation abolishes CGS-induced tachycardia. In eight intact fetuses (>0.8 term), intra-arterial CGS infusion (6 μg ⋅ min-1 ⋅ kg estimated fetal wt-1) increased mean arterial [Formula: ...