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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study, the effect of selective glucocorticoid deficiency on renal water excretion was investigated in conscious, trained, adrenalectomized dogs. The animals were studied before and after a water load while on replacement therapy of desoxycorticosterone acetate, 5 mg/day, and dexamethasone, 0.8 mg/day (group I), and while off dexamethasone for 5-9 days (group II). Before the water load the weight, inulin space, cardiac output, blood pressure, glomerular filtration rate, renal blood flow, plasma osmolality, and plasma antidiuretic hormone measured by radioimmunoassay were similar in both groups I and II. However, after a 40 ml/kg water load a marked impairment in renal water excretion in the glucocorticoid deficient dogs became apparent. Maximal free water clearance was -0.046+/-0.16 vs. 6.51+/-0.72 ml/min (P < 0.001) and minimal urinary osmolality was 425+/-56 vs. 82+/-3.5 mosmol/kg H(2)O (P < 0.001) in group II as compared to group I. Plasma antidiuretic hormone was maximally suppressed during the water load in group I to 0.34+/-0.08 pg/ml but remained elevated at 9.18+/-1.79 pg/ml (P < 0.005) in group II. This nonsuppressibility of plasma antidiuretic hormone during water loading in group II was associated with a significant tachycardia of 145+/-6 vs. 87+/-6 beats/min (P < 0.001) in group I and a significantly lower stroke volume of 27+/-0 vs. 59+/-0.5 ml/beat (P < 0.001). In conclusion, our results implicate a persistent secretion of antidiuretic hormone as an important factor in the impaired water excretion of glucocorticoid deficiency. A deleterious effect of glucocorticoid deficiency on cardiac function was observed and this hemodynamic alteration could be involved in initiating a nonosmolar, baroreceptor-mediated release of vasopressin.
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PMID:Role of plasma vasopressin in impaired water excretion of glucocorticoid deficiency. 70 72

Gill ventilation, stroke volume and frequency, %O2 utilization and oxygen uptake, and dorsal aortic blood oxygen tension, content, pH and oxygen affinity have been determined during normoxia and during a range of hypoxic exposures in the sturgeon, Acipenser Transmontanus. In air-equilibrated water gill ventilation was 350 ml/kg/min, % utilization was 35--40%, and oxygen uptake at 15 degrees C was 55--60 ml O2/kg/h. Dorsal aortic blood PO2 was 90 mm Hg and blood O2 content at a normal pHa of 7.84 was 7.0 vol%. Vg fell considerably through a reduction in branchial stroke volume when PIO2 was reduced from 150 to 100 mm Hg. Although % utilization remained unchanged, VO2 was halved, clearly identifying Acipenser as an O2 conformer with a critical O2 tension just below air saturation. At a PIO2 of 60 mm Hg VO2 was only 15% of that at normoxic levels falling to only 5% at a PIO2 of 30 mm Hg. There was no hypoxic bradycardia. There was no repayment of an oxygen debt even after severe hypoxic exposure in Acipenser, and pHa remained unchanged under all experimental conditions, a response incompatible with lactate or succinate production. It is concluded that the sturgeon reduces total energy expenditure during hypoxic exposure, rather than switching from aerobic to anaerobic metabolism.
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PMID:Oxygen uptake and transport during hypoxic exposure in the sturgeon Acipenser transmontanus. 70 79

In dogs anesthetized with chloralose-urethan on right heart bypass, left ventricular (LV) performance was assessed at constant LV stroke work before and for up to 2.5 h after crystalloid hemodilution was established. Lowering the hematocrit from 43.3 +/- 1.3% to 13.6 +/- 1.7% (SE) did not significantly change LV end-diastolic pressure (LVEDP) initially. After 80 min LVEDP increased slightly by 1.7 +/- 0.6 cmH2O (P less than 0.05) at a stroke work of 17.3 +/- 2.3 g.m. The value of dP/dt did not change significantly throughout. When LV function curves were generated by increasing cardiac output, the stroke work attained at an LVEDP of 10 cmH2O decreased with hemodilution from 23.9 +/- 3.5 to 20.8 +/- 3.9 g.m (NS). LV wall water content increased with hemodilution, from which it could be calculated that there was an 18.6% increase in LV mass. Thus, despite an increase in LV external girth demonstrated by LV circumferential gauges, it is possible that increased wall thickness due to the water gain resulted in little change or an actual decrease in LV end-diastolic volume. Thus, profound hemodilution can be attained with only slight depression of LV performance.
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PMID:Ventricular performance and myocardial water content during hemodilution in dogs. 73 64

Heat tolerance was assessed by magnitude of strain induced in the body as a whole by heat load. The strain was represented by a combination of relative water loss, relative rise in rectal temperature and relative salt loss, using those critical values of the three factors which cause heat stroke (40.6 degrees C), water depletion heat exhaustion (7% of body weight) and salt depletion heat exhaustion (0.75 g per kg of body weight). As this numerical heat tolerance index is defined as the degree of disturbance induced by heat exposure concerning thermal regulation, water and electrolyte metabolism, the magnitude of the index is inversely proportional to that of heat tolerance. Our studies showed that adaptive changes in heat tolerance of unacclimatized subjects during short-term heat acclimatization could be followed up by this heat tolerance index and that superior heat tolerance of residents in subtropical zone and athletes could by reasonably evaluated by the index. Thus, it might be said that this numerical heat tolerance index is a reliable index for the assessment of heat tolerance.
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PMID:Index for the assessment of heat tolerance. 75 47

Hemodynamic studies were carried out in 19 patients with left ventricular failure complicating acute myocardial infarction. Fourteen patients were studied before and after the intravenous administration of 0.5 mg/kg of furosemide, and five patients served as a control group. Serial measurements included intracardiac pressures, cardiac output and lung water by a double isotope technique. A significant reduction was noted in right atrial (P less than 0.005), pulmonary arterial (P less than 0.0005) and pulmonary wedge pressures (P less than 0.0005) after administration of furosemide. Only the change in right atrial pressure was significantly different from that in the control group (P less than 0.05). Lung water was not changed in 4 patients studied 2 hours after administration of furosemide but was significantly changed in the remaining 10 patients studied 4 to 24 hours after furosemide (P = 0.0001). This change was also significantly different from values in the control group (P less than 0.05). The patients with no reduction in excess lung water also had a smaller reduction in pulmonary wedge pressure and a lower pretreatment stroke work index than the other patients. The mobilization of excess lung water in patients with acute myocardial infarction complicated by left ventricular failure has several features. Despite a prompt diuresis, the reduction in lung water is delayed for at least several hours after the administration of furosemide and may be related to the degree of left ventricular dysfunction. Venodilation may be a major result of treatment with furosemide.
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PMID:Effect of furosemide on hemodynamics and lung water in acute pulmonary edema secondary to myocardial infarction. 75 75

The respiratory effects on heart rate (HR), right ventricular stroke volume (SVRV), and the pulmonary arterial flow (PAF) have been studied beat-by-beat in 7 conscious, healthy subjects. Tidal volumes (VT) of 1.0 and 2.0 liters at a breathing rate of 6 cXmin-1 were used as controls. With identical VT and respiratory rate intrathoracic pressure was affected by (A) negative inspiratory pressure (NIP) of 5 cm of water and (B) with intermittent positive pressure ventilation (IPPV). In the control experiments all subjects exhibited an inspiratory increase in HR (respiratory sinus arrhythmia) as well as in SVRV. With VT of 1.0 liter, NIP augmented the inspiratory increase in SVRV and the respiratory oscillations of PAF. IPPV decreased SVRV and HR during inspiration. It is concluded that NIP and IPPV affect the SVRV and the right heart blood flow. The similar effects on HR and SVRV suggest a relationship which might be explained by heart-rate-regulating reflexes from the heart.
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PMID:Respiratory sinus arrhythmia in man: relation to right ventricular output. 79 May 35

Artificial embolization of the middle cerebral artery (MCA) was produced in the primate, with a technique similar to that described by Luessenhop and Spence (1960) for the treatment of an inoperable arteriovenous malformation in the territory of the MCA. Silicone spheres (1 to 1.5 mm in diameter) were introduced into the internal carotid artery (ICA) via the external carotid artery (ECA). Emboli (1 to 1.3 mm) passed into the anterior cerebral artery (ACA) in 12%, and into the MCA in 50%. Emboli (1.2 to 1.5 mm) stopped at the ICA bifurcation in 54%. In all primates (82.35%1 in which the emboli occluded the ICA bifurcation or the MCA, immediate contralateral hemiplegia developed. The correlation of the anatomical characteristics of the intracranial vasculature of the ICA bifurcation, the diameter of the emboli, and the anatomical localization of the silicone spheres suggests that this experimental model can produce a selective acute "point" occlusion of the MCA in at least 75% of the cases without violating the cranium, in which the resultant changes in the distribution of water and electrolytes in the brain during the acute ischemic event in the territory of the MCA of the primate can be studied.
Stroke
PMID:Artificial embolization of the middle cerebral artery in primates. Description of an experimental model with extracranial technique. 80 99

Ketamine, currently being evaluated as an obstetric anaesthetic agent, is said to provide analgesia without depression of the protective airway reflexes or depression of the respiratory or cardiovascular systems. We have studied the effects of ketamine on the uterine blood flow, the foetus and the newborn in five monkeys (Macaca nemistrina). Uterine blood flow, (UBF) was measured by the steady-state infusion technique using tritiated water as the indicator. All of the variables were measured during a control period and again at 10 and 90 min after the administration of ketamine in doses of 2 mg/kg in three monkeys or 1 mg/kg in two. Maternal respiration was maintained at normal physiological levels without significant variation. The maternal mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) did not change significantly, but heart rate (HR) did increase significantly following the injection of ketamine and remained increased for the duration of the study. UBF, a-v oxygen difference, and the oxygen consumption of the uterus and its contents remained stable throughout. During the intrauterine period the foetus did not seem to be affected by the two doses of ketamine. However, the three newborn monkeys delivered of the mothers who had reveived ketamine 2 mg/kg had profound respiratory depression. This was not seen in the two infants delivered from mothers receiving 1 mg/kg. Others have shown that neonatal depression is dose- and time-related. We conclude that ketamine should be administered to obstetric patients in small single doses or by continuous infusion in very low concentrations.
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PMID:Respiratory depression in newborn monkeys at Caesarean section following ketamine administration. 81 Dec 35

In normothermic anesthetized cats cerebral blood flow was interrupted completely for one hour by arterial clamping and induced hypotension. The effect of ischemia on the ionic gradients of the cerebral cortex was assayed by determining total cortical electrolytes and by recording the activities of extracellular potassium ([K+i1e) and subarachnoid sodium ions ([Na+])s) with ion-sensitive electrodes. During ischemia [K+]e increased from 3.3+/-0.3 to 56+/-5.4 mEq per liter (means+/-SE) and [Na+]s decreased from 133+/-3.8 to 53+/-5.8 mEq per liter. When the brains were recirculated with blood after one hour's ischemia, [K+]e and [Na+]a gradually returned to normal within 45 minutes. The calculated intracellular uptake of sodium during ischemia amounted to 139 mEq per kilogram dry weight, whereas the intracellular release of potassium was only 64 mEq per kilogram. The increase in intracellular cation was accompanied by a movement of water from the extracellular into the intracellular compartment, causing a reversible shrinkage of the extracellular space from 18.9 to 8.5 vol %. The changes in ionic gradients were related to the development and resolution of ischemic brain swelling, and to the elctrophysiological events during and after ischemia.
Stroke
PMID:Cation activities in reversible ischemia of the cat brain. 83 60

The cardiopneumogram has been reinvestigated as an index of stroke volume and cardiac output in anaesthetized dogs. Using a water-filled oesophageal balloon to calibrate the system good correlations have been found between the values derived from dye dilution and the indices obtained from the cardiopneumogram.
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PMID:An index of cardiac output derived from the cardiopneumogram. 84 15


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