Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085383 (hypocapnia)
 1,697 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied the effects on breathing of seizures induced by focal injection of penicillin G into the parietal cortex in 13 anesthetized cats. Electrocorticograms, ventilation, end-tidal PCO2, and intrapleural and arterial pressures were monitored; changes of these variables were related to the stages of motor seizure. The first respiratory responses, tachypnea and hyperpnea, usually occurred before any peripheral muscular contractions developed. Progression of the seizure was always accompanied by further tachypnea and hyperpnea. The hyperpnea associated with all stages of seizure activity resulted in hypocapnia, which was sustained even during prolonged tonic-clonic motor convulsions that caused a threefold increase of metabolic rate. The extreme tachypnea of tonic generalized convulsions led to increased end-expiratory lung volume because of dynamic hyperinflation associated with very short expiratory durations in the tonic phase. We suggest that the profound effects of seizures on respiration are by feedforward mechanisms from the cortical focus itself and from subcortical circuits, such as hypothalamus, that become involved during seizure propagation and generalization. Peripheral respiratory feedback mechanisms are not important for the genesis of seizure-induced hyperpnea.
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PMID:Respiratory responses to focal and generalized seizures in cats. 203 5

Rhythmic activity was observed in over 100 pial vessels in 58 cats with a photometric technique through a cranial window. Diameter oscillations with a frequency of mostly 5/min were present at normal mean arterial pressure (MAP) in about half of the animals. When spontaneous activity was absent the same type of oscillations could be provoked by varying MAP, mostly by lowering it to a level of around 60 mm Hg. If a rhythmic activity was present, it could be abolished by increasing and decreasing MAP. Likewise, rhythmic activity ceased during strong vasodilatation caused by hypercapnia, hypoxia, Ca antagonists or other vasoactive drugs. Rhythmic activity also decreased in amplitude or disappeared with vasoconstriction accompanied by a stable MAP. Rhythmic activity of pial vessels thus seemed to occur within an as yet unspecified range of vessel wall tensions mediated via intraluminal pressure and a state of constriction or dilatation. This rhythmic activity was not primarily influenced by sympathetic stimulation, alpha-sympathetic blockade, hyper- or hypocapnia, hypo- or hyperoxygenation. Moreover, the vascular activity fits well with the description of rhythmic smooth muscle activity in other vascular beds and organs in vitro and in vivo, ascribed to myogenic regulatory processes. Therefore, it is suggested that the rhythmic activity of pial vessels might be an expression of myogenic blood flow regulatory activity in the brain.
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PMID:Rhythmic activity of cat pial vessels in vivo. 611 76

The relative acute cardiovascular toxicity among three novel antidepressants: maprotiline, mianserin and nomifensine, has been assessed in conscious rabbits ip injected at 50 mg/kg, throughout a 150 min observation period. No death was observed in mianserin rabbits (n = 6), but 3 in the maprotiline rabbits (n = 8) and 1 death in the nomifensine group (n = 8), within the 2 hours. Cardiac output and renal blood flow were determined by the radioactive Sephadex microspheres method. Cardiac output values were significantly lowered (-29%) at 120 min only in mianserin rabbits, whereas renal blood flow values were reduced by 46.8% (mianserin, 35.8% (maprotiline) and 28% (nomifensine) at 120 min. In mianserin and maprotiline rabbits left ventricular pressure and mean arterial pressure fell significantly, but remained unchanged in nomifensine group. ECG disturbances consisting of ventricular and supraventricular extrasystoles were seen in all the injected rabbits, but QRS widening and right bundle branch block were solely observed after maprotiline and mianserin. Nomifensine rabbits experienced severe seizures with hypocapnia and metabolic acidosis. The drug myocardial/plasma ratio ranged between 59.3 (maprotiline) 13.25 (mianserin) and 0.92 (nomifensine). A rise in plasma catecholamines (epinephrine) was documented after mianserin but not after nomifensin and maprotiline. Nomifensine exhibited much lesser cardiotoxicity than mianserin and maprotiline at this dose (50 mg/kg), but induced more convulsions.
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PMID:Relative acute cardiovascular toxicity induced by maprotiline, mianserin and nomifensine in conscious rabbits. 662 Apr 40

A solution containing S-nitroso-N-acetylpenicillamine (SNAP), a nitric oxide (NO.-releasing compound, was microinjected in doses of 0.25-2 mumol into a lateral ventricle of conscious rats. SNAP produced dose-dependent convulsions similar to those associated with limbic stimulation, such as tonic extension of the hindlimbs and tail, and dystonia of the forepaws. At 2 mumol, SNAP evoked hyperventilation (arterial hypocapnia), arterial hyperglycemia and caused necrotic lesions of periventricular gray (e.g. lateral septal nucleus) and white matter structures. In the caudate nucleus and lateral septal nucleus ipsilateral to injection, SNAP elicited a bipolar metabolic pattern of low glucose metabolism proximal to the ventricle with higher values occurring more distally. In control studies, we proved that the residue of SNAP decomposition, N-acetylpenicillamine disulfide injected intraventricularly (2 mumol), was without physiological, behavioral, or histological effects. Ventricular pretreatment with methylene blue (2 nmol), a putative inhibitor of guanylate cyclase and superoxide generator, suppressed several of the behavioral manifestations of 1 mumol SNAP, such as the forepaw dystonia, squinting, and facial clonus, but was ineffective on the physiological and histological variables affected by the 2 mumol SNAP dose. Another NO. donor, sodium nitroprusside (2 mumol), produced fewer behavioral and cytotoxic effects over a 55-min observation period, but caused more intense and widely distributed metabolic stimulation, especially in commissural and projection white matter tracts. The results are the basis for a conscious rat model using intraventricular injection of nitrocompounds to examine the physiological, behavioral, metabolic and cytotoxic properties of NO. in the brain.
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PMID:Neurotoxicity in conscious rats following intraventricular SNAP, a nitric oxide donor. 796 12

A 92-year-old woman was admitted to our hospital due to hypertension, nausea, pain in the anterior part of the chest, epigastralgia, and tachypnea. During the initial examination of the patient in the emergency ward, she was very excited, howled, and both her hands were numb. Arterial blood gas analysis revealed a marked alkalemia (pH greater than 7.55) and hypocapnia (Pco2 24.1 mmHg). After paper bag re-breathing, the pH and Pco2 were within normal limits. Because there was no lesion in the lungs or the brain that would account for hyperventilation and convulsions, the attack was considered to be a manifestation of hyperventilation syndrome should be carefully considered in the differential diagnosis of disturbance of consciousness even in elderly patients.
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PMID:[Hyperventilation syndrome in a very old woman]. 915 99