Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of 1-h exposure to hypercapnia (PaCO2, 90-110 MMHg) on cerebral indole amine metabolism were studied in rats by measurement of cerebral hemisphere contents of tryptophan, 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA), 5-HIAA content was increased after 1-h exposure to hypercapnia, whereas tryptophan, 5-HTP, and 5-HT remained unchanged from control. The accumulation of 5-HTP after decarboxylase inhibition with 3-hydroxybenzyl hydrazine was increased in hypercapnic rats and indicated an increased activity of tryptophan hydroxylase. During the 1-h exposure to hypercapnia there was increased accumulation of 5-HT after monoamine oxidase inhibition with pargyline and increased accumulation of 5-HIAA arter probenecid. The results indicate an increased synthesis and degradation of indole amines in acute hypercapnia.
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PMID:The effects of acute hypercapnia on cerebral indole amine metabolism. 30 15

Aortic chemoreceptor activity, from single- or few-fiber afferent nerve preparations, was measured in response to dopamine and a dopaminergic blocker, haloperidol, in 18 anesthetized cats. In six of these cats the effect of dopamine was assessed before and after inhibiting monoamine oxidase (MAO) by pargyline. Intravenous dopamine infusion (7-14 microgram X kg-1 X min-1) had a generally inhibitory effect on aortic chemoreceptor activity, but the magnitude of this effect varied with arterial partial pressure of O2 (Pao2) levels. The inhibitory effect of dopamine increased as Pao2 levels fell, and at severely hypoxic Pao2 levels (below 30 Torr) exogenous dopamine had no significant effect. The inhibitory effect of dopamine also increased during hyperoxic hypercapnia. Blockade of dopamine receptors in the aortic body by haloperidol-stimulated chemoreceptor activity significantly during hypoxia, suggesting an O2-dependent release of dopamine from the aortic body as Pao2 falls. Inhibition of MAO by pargyline had no significant effect on the control rate of activity at any level of Pao2 but augmented the inhibitory effect of exogenously administered dopamine. These data indicate that MAO is not significantly involved in the degradation of endogenous dopamine at the aortic receptor sites, but may participate in the degradation of exogenous dopamine.
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PMID:Aortic body chemoreceptor responses to dopamine, haloperidol, and pargyline. 712 79

Dopamine (DA) and noradrenaline (NA) were measured in the rabbit carotid body (CB) in vitro bv HPLC-ED under the following experimental conditions: 1h superfusion in normoxic, hypoxic (10% O2 in N2) or hypercapnic (8% CO2, 20% O2, 72% N2) medium, 5h superfusion in normoxia or hypoxia. The contents of DA and NA were decreased by hypoxia and hypercapnia after 1 h and 5h indicating a possible DA and NA secretion. Under the same experimental conditions synthesis of DA and NA and catabolism of DA were studied with enzymatic inhibition of tyrosine hydroxylase and monoamine oxidase (MAO) respectively. In hypoxia (1 h and 5h) the rate constant of DA synthesis was the same as in normoxia; however NA synthesis was decreased after 1 h hypoxia. On the contrary, hypercapnia, appeared to be a very effective stimulus of DA and NA synthesis.
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PMID:Dopamine metabolism in the rabbit carotid body in vitro: effect of hypoxia and hypercapnia. 810