Doxapram inhibits carotid sinus baroreceptors in rabbits.

1 To clarify the effects of doxapram on the baroreflex, we recorded carotid sinus nerve (CSN) activity in isolated and perfused carotid artery bifurcations of rabbits. 2 The CSN activity due to chemoreceptor stimulation was blocked by resection of the nerve branches from the carotid body. After the resection, the CSN activity was correlated to increase of carotid sinus (CS) pressure. 3 Administration of doxapram reduced the CSN activity originating from baroreceptors. The effect of doxapram on baroreceptors was dose dependent and reversible. 4 It is unlikely that doxapram altered CS wall mechanics because CS pressure did not change in the presence of the drug. 5 We conclude that doxapram acts on the cardiovascular system in part by inhibiting the negative feedback loop that originates in CS baroreceptors.

[1]  S. Lahiri,et al.  Regulation of oxygen sensing in peripheral arterial chemoreceptors. , 2001, The international journal of biochemistry & cell biology.

[2]  F. Abboud,et al.  A Molecular Component of the Arterial Baroreceptor Mechanotransducer , 1998, Neuron.

[3]  F. Abboud,et al.  The Prostacyclin Analogue Carbacyclin Inhibits Ca2+‐Activated K+ Current in Aortic Baroreceptor Neurones of Rats , 1997, The Journal of physiology.

[4]  F. Abboud,et al.  Gadolinium inhibits mechanoelectrical transduction in rabbit carotid baroreceptors. Implication of stretch-activated channels. , 1994, The Journal of clinical investigation.

[5]  F. Abboud,et al.  Modulation of baroreceptor activity by ionic and paracrine mechanisms: an overview. , 1994, Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas.

[6]  C. Peers.  Effects of doxapram on ionic currents recorded in isolated type I cells of the neonatal rat carotid body , 1991, Brain Research.

[7]  N. Terui,et al.  Arterial baroreceptor reflex: Its central and peripheral neural mechanisms , 1990, Progress in Neurobiology.

[8]  F. Abboud,et al.  Prostaglandins contribute to activation of baroreceptors in rabbits. Possible paracrine influence of endothelium. , 1990, Circulation research.

[9]  F. Sachs,et al.  Block of stretch-activated ion channels in Xenopus oocytes by gadolinium and calcium ions. , 1989, Science.

[10]  N. Dawson,et al.  Brain stem projections of the glossopharyngeal nerve and its carotid sinus branch in the rat , 1987, Neuroscience.

[11]  S. Donoghue,et al.  The central projections of carotid baroreceptors and chemoreceptors in the cat: a neurophysiological study. , 1984, The Journal of physiology.

[12]  D. McDonald,et al.  Morphology of the rat carotid sinus nerve. I. Course, connections, dimensions and ultrastructure , 1983, Journal of neurocytology.

[13]  S. Lahiri,et al.  Stimulation of carotid chemoreceptors and ventilation by doxapram in the cat. , 1982, Journal of applied physiology: respiratory, environmental and exercise physiology.

[14]  N. Mizuno,et al.  Central distribution of afferent and efferent components of the glossopharyngeal nerve: An HRP study in the cat , 1982, Brain Research.

[15]  R. Mitchell,et al.  Potencies of doxapram and hypoxia in stimulating carotid-body chemoreceptors and ventilation in anesthetized cats. , 1975, Anesthesiology.

[16]  S. C. Wang,et al.  Selective respiratory stimulating action of doxapram compared to pentylenetetrazaol. , 1974, The Journal of pharmacology and experimental therapeutics.

[17]  K. Kikuchi,et al.  Doxapram stimulates carotid body with different mechanisms from hypoxic chemotransduction. , 2003, Advances in experimental medicine and biology.

[18]  K. Barrington,et al.  Physiologic effects of doxapram in idiopathic apnea of prematurity. , 1986, The Journal of pediatrics.