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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cross-clamping of the ascending aorta in dogs for 15 min produced severe neurological deficit, observed for up to 20 h. Immediately after restoration of the circulation, the intracranial pressure in the cisterna magna increased transiently to a mean peak of 22.8 Torr (SD +/- 1.7) because of a compensatory increase in systemic arterial pressure, without a fall in cerebral perfusion pressure. The intracranial pressure returned to control values 15-30 min after ischaemia and showed no secondary rise during the 8 h of observation. The electroencephalogram became isoelectric 34 +/- 6.5 s (mean +/-SD) after circulatory occlusion, and was abnormal when it reappeared 5 h 36 min (SD +/- 2 h 4 min) after the circulation was restored. The electrical impedance of the brain increased immediately after ischaemia and returned rapidly towards pre-ischaemic values during re-perfusion. The cerebral water had not increased measurably 4 h after ischaemia. After ischaemia, the lactate concentration in the cerebrospinal fluid increased to 4.7 mequiv./1(SEM +/-0.1) and the pH decreased to 7.17 (SEM +/-0.02); both returned to control values after 3.5 h. The cerebral glucose uptake was decreased 35 min after ischaemia, cerebral oxygen uptake remained unchanged but cerebral blood flow decreased (P less than 0.05 at 90 min). Immediately after cardiac arrest, recovery was impaired more by the presence of focal abnormal brain perfusion than by intracranial hypertension.
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PMID:Total brain ischaemia in dogs: cerebral physiological and metabolic changes after 15 minutes of circulatory arrest. 0 Jul 50

Muscular exercise is associated with hypermetabolism and increased hypoxic ventilatory response (HVR). In order to dissociate mechanical and metabolic factors, the effect of hypermetabolism on hypoxic ventilatory response was evaluated at rest. Carbohydrate and protein feeding increases metabolic rate, and their effects on chemosensitivity, ventilation, and blood pH were evaluated in six normal subjects 2 h and 3 h after calorically equal test meals (1,000 cal). After carbohydrate, base-line oxygen consumption (Vo(2)) increased from 237+/-11.3 ml/min (SEM) to 302+/-19.4 (P < 0.001) and 303+/-18.5 (P < 0.001) at 2 h and 3 h, respectively. Hypoxic ventilatory response, measured as shape parameter A, increased from a control of 144+/-11.8 to 330+/-61.0 (P < 0.01) at 2 h and 286+/-57.0 (P < 0.05) at 3 h. These changes were associated with a mild metabolic acidosis as pH decreased from a control of 7.402+/-0.004 to 7.371+/-0.009 (P < 0.005) at 2 h and 7.377+/-0.008 (P < 0.005) at 3 h. After protein, Vo(2) increased from 241+/-6.7 to 265+/-6.2 (P < 0.02) and 270+/-5.4 (P < 0.001), an overall increase less than that which occurred after carbohydrate (P < 0.01). Hypoxic ventilatory response increased from 105+/-14.5 to 198+/-24.3 (P < 0.02) at 2 h and 219+/-17.3 (P < 0.01) at 3 h, which was not different from the increase with carbohydrate. After protein, no acidosis occurred. Thus, after protein, HVR increased despite the absence of a systemic acidosis. We conclude that both carbohydrate and protein feedings are associated with resting hypermetabolism and increased HVR compared with the fasting state. For both meals, increased metabolic rate was correlated with increased hypoxic response.
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PMID:Effects of hypermetabolism on ventilation and chemosensitivity. 1

Fourteen intubated infants recovering from neonatal respiratory disease had arterial blood gases and lung mechanics measured in the supine position and in two variants of the prone position. Prone positioning resulted in significant increases in mean (+/- SEM) arterial oxygen tension (Pa(o2 70.4 +/- 2.5 to 81.1 +/- 4.4mm Hg), dynamic lung compliance (1.7 +/- 0.24 to 2.55 +/- 0.37 ml/cm H2O),and tidal volume (8.6 +/- 1.0 to 10.5 +/- 1.2 ml) when all prone values were compared to supine values. Prone positioning with the abdomen protruding freely, when compared to all supine values, was associated with significantly increased dynamic lung compliance and tidal volume. Values for prone-abdomen free were not significantly different from values for prone-abdomen restricted. This suggests that there are clinical benefits from prone positioning in neonates recovering from respiratory disease.
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PMID:Improved oxygenation and lung compliance with prone positioning of neonates. 3 49

We measured rat brain cortex PO2 (PtO2) with gold microelectrodes (tip diameter 5--10 micron) for up to 2 hours after 16 min of transient global brain ischemia with and without thiopental 90 mg/kg infused iv over 60 min beginning at 5 min postischemia. Seventeen rats were immobilized and mechanically ventilated on 1% halothane in oxygen with continuous monitoring of PtO2, ECG, end-expiratory CO2, rectal temperature, and arterial blood pressure. Global ischemia was induced by trimethaphan hypotension to an MAP of about 50 torr and a neck tourniquet inflated to 1500 torr. Postischemia, nine control rats (11 PtO2 measurements) were untreated and eight rats (8 PtO2 measurements) received thiopental 90 mg/kg. Preischemia, PtO2 values in both groups ranged from less than 5--70 torr with values of greatest frequency between 10 and 15 torr. Postischemia, PtO2 in control rats peaked at 45 +/- 8 (SEM) torr at 20 min. In thiopental treated rats, peak PtO2 was 24 +/- 6 torr at 10 min postischemia. Relative frequency histograms of PtO2 revealed that PtO2 in thiopental treated rats was lower (p less than 0.05) between 15 and 30 min postischemia. The magnitude of the decrease in PtO2 between 105 and 120 min postischemia appeared to correlate directly with the absolute preischemic value (i.e., the higher the preischemic PtO2, the greater the decrease in PtO2 postischemia). These results suggest that thiopental administered in large doses in early postischemia does not improve brain oxygenation secondary to a reduction in brain oxygen consumption. The relevance of the correlation between the magnitude of the fall in PtO2 postischemia and the magnitude of the preischemic value is discussed.
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PMID:Postischemic brain oxygenation with barbiturate therapy in rats. 3 43

Baboons anaesthetized with halothane and nitrous oxide in oxygen were given Althesin 0.05 ml kg-1 i.v. Cerebral blood flow (c.b.f.) was measured by an electromagnetic flowmeter and by xenon clearance whilst extracellular fluid (e.c.f.) pH of the parietal cortex was measured with a micro pH electrode. Carotid blood flow (carBF) began to decrease and carotid vascular resistance (carVR) to increase 2.0 s (SEM 0.3) after the slowing of the e.e.g. produced by Althesin, while e.c.f. pH began to change to alkaline 10.5 s (SEM 1.0) after the e.e.g. change. The first statistically significant increase in mean e.c.f. pH occurred 25 s after the Althesin-induced change in the e.e.g. The duration of the changes in carVR and e.c.f. pH were 7 and 5 min respectively. It is concluded that the change in e.c.f. pH cannot have initiated the increase in carVR which followed the cerebral matabolic depression produced by Althesin. The later alkaline shift in e.c.f. pH may, however, have maintained the increased carVR during the duration of cerebral metabolic depression produced by Althesin.
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PMID:Relationship between cerebral blood flow changes and cortical extracellular fluid pH during cerebral metabolic depression induced by althesin. 4 61

7 consecutive patients with congestive heart failure refractory to standard therapy were treated with nitroglycerin ointment (GTNO). The pulmonary wedge pressure decreased from a control value of 30+/-1 to 15+/-1 mm Hg (mean +/-SEM), and the arteriovenous oxygen difference narrowed from 6.8+/-0.5 to 5.5+/-0.3 ml%, after GTNO therapy. The heart rate decreased in 5 patients and the systolic blood pressure was either unchanged or decreased slightly. A reduction in the echocardiographic end diastolic dimension was noted in all patients. The transmyocardial gradient (systemic artery diastolic pressure - pulmonary artery wedge pressure) increased in all except 1 subject. The double product decreased in 5 of the 7 patients. Hemodynamic improvement was maintained for 4.5-7 h. All patients were symptomatically improved on chronic GTNO treatment. Our results indicate that GTNO is a useful agent in the management of heart failure which is unresponsive to standard therapy.
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PMID:Use of nitroglycerin ointment in congestive heart failure. Results of acute and chronic therapy. 10 Feb 19

Twelve chair-restrained baboons (Papio cynocephalus) were conditioned with operant techniques and a food reward to perform 4 min of dynamic leg exercise. During the last minute of exercise, blood flow through the left renal artery, measured by an electromagnetic flow transducer, was decreased 19 +/- 2% SEM with respect to the minute of rest preceding the exercise. This response occurred within 1.5 min, was maintained throughout the exercise, and recovered to control within 2 min. Mean arterial blood pressure rose 17 +/- 2%; renal vascular resistance, 46 +/- 6%; heart rate, 42 +/- 4%; and whole-body oxygen consumption, 233 +/- 19%. Behavioral situations simulating the arousal and feeding components of the exercise task, but not requiring muscular exertion, did not alter renal blood flow. In four animals, blood flow to the contralateral but surgically denervated kidney was measured; it increased transiently at the onset of exercise, but returned to control by the last minute of work. Thus, the baboon, like man, shows a decrease in renal blood flow during exercise. This response has a rapid onset and recovery and is primarily neurally mediated.
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PMID:Decreased renal blood flow in the baboon during mild dynamic leg exercise. 10 12

Oxygen half-saturation of blood (P50), 2,3-diphosphoglycerate concentration (2,3-DPG) and Bohr effect were determined in male, and nonpregnant and pregnant female guinea pigs, according to a randomized block design. P50 was significantly higher in the female group (26.3 Torr plus or minus 0.22 SEM) than in the male group (24.8 Torr plus or minus 0.26 SEM) and was significantly lower in both these groups than in the pregnant group (27 Torr plus or minus 0.35 SEM). This difference in oxygen affinity was explained by differences in 2,3-DPG: 1.08 plus or minus 0.02 SEM in males, 1.24 plus or minus 0.03 in non-pregnant females and 1.34 plus or minus 0.03 mol/mol HB in pregnant females P50, 2,3-DPG and haemoglobin concentrations were significantly correlated for the ensemble of the 3 groups. There was no significant difference in Bohr effect between the 3 groups.
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PMID:Dependence of 2,3-DPG and oxygen affinity of haemoglobin on sex and pregnancy in the guinea-pig. 23 8

Adaptations of the method of Takahashi et al. (1966. J. Gen. Physiol. 50:317-333) were used to test the validity of the one-dimensional diffusion equation for O2 in the resting excised frog sartorius muscle. This equation is: (formula: see text) where x is the distance perpendicular to the muscle surface. t is time, P(x, t) is the partial pressure of O2,D and alpha are the diffusion coefficient and solubility for O2 in the tissue, and Q is the rate of O2 consumption. P(O, t), the time-course of PO2 at one muscle surface, was measured by a micro-oxygen electrode. Transients in the PO2 profile of the muscle were induced by two methods: (a) after an equilibration period, one surface was sealed off by a disc in which the O2 electrode was embedded; (b) when PO2 at this surface reached a steady state, a step change was made in the PO2 at the other surface. With either method, the agreement between the measured P(O, t) and that predicted by the diffusion equation was excellent, making possible the calculation of D and Q. These two methods yielded statistically indistinguishable results, with the following pooled means (+/- SEM): (formula: see text) At each temperature, D was independent of muscle thickness (range, 0.67-1.34 mm). The activation energy (EA) for diffusion of oxygen in muscle was -3.85 kcal/mol, which closely matches the corresponding value in water. Together with absolute values of D in water taken from the literature, the present data imply that (Dmuscle/DH2O) is in the range 0.59-0.69. This value, and that of EA, are in agreement with the theory of Wang (1954, J. Am. Chem. Soc. 76:4755-4763), suggesting that with respects to the diffusion of O2, to a useful approximation, frog skeletal muscle may be considered simply as a homogeneous protein solution.
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PMID:Diffusion and consumption of oxygen in the resting frog sartorius muscle. 30 46

Plasma vasopressin concentrations were estimated in twelve patients undergoing cardio-pulmonary bypass for open heart surgery. In six patients anaesthesia was maintained with 66% nitrous oxide in oxygen, whilst the remaining six additionally received halothan as a vasodilator during the bypass period. Induction of anaesthesia had little effect on plasma vasopressin concentrations, whilst marked increases were seen during surgery and bypass in both groups of patients. However, in those patients receiving halothane, significantly higher concentrations were reached, a maximun b36.1 +/- 8.9 (SEM) muu/ml being seen in contrase to 15.4 +/- 2.2 muu/ml in the group receiving nitrous oxide in oxygen alone.
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PMID:The effects of halothane on plasma vasopressin during cardio-pulmonary bypass. 32 88


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