ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

L-Dihydroxyphenylalanine (l-dopa), effective in the treatment of Parkinson's disease, frequently causes postural hypotension and arrhythmias. The large doses used may alter peripheral adrenergic function. To evolve a rational anesthetic management for the increasing number of parkinsonism patients maintained on l-dopa therapy, central and peripheral catecholamine stores and the turnover of myocardial norepinephrine (NE) as affected by L-dopa were studied in rats. Large doses of l-dopa (100–200 mg/kg, i.p.) increased die concentration of dopamine (DM) in the brain without changing the concentration of NE significantly. DM accumulated in the heart following l-dopa treatment, accompanied by a decrease in XE concentration. After labelling of the myocardial NE store with tracer doses of5H-NE, treatment with l-dopa caused a more rapid decline of specific activity of myocardial NE. Therefore, DM may displace NE from peripheral sympathetic nerve endings and interfere with adrenergic transmission.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The effects of diazepam (0.14 mg/kg) on steady-state gas exchange were studied in 13 patients, and the responses to a carbon dioxide stimulus using a recently introduced rebreathing technique are described. There were significant increases in VD/VTand Paco2, and a decrease in VT. &OV0312;Eand &OV0312;o2- were unchanged. In more than half of the patients there was a depression of the slope of the ventilatory response to CO2, or a depression of the &OV0312;E57, or both.The evidence indicates that diazepam depresses the ventilatory response to CO2, and also modifies the characteristics of gas exchange within the lung, producing a rise in VD/VT, and often associated with a rise in Pactco2.The variation in incidence and severity of changes in respiratory function among individuals is evidenced in this study of the effects of diazepam.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

In a study of ten patients with obstructive pulmonary disease, 0.11 mg/kg of diazepam produced small reductions in VE/VT, and &OV0312;o2in most of the subjects. Paco2rose in every subject (mean increase 3.5 torr) and most subjects had increases in VD/VT. In half of the subjects there were reductions in slopes of the ventilatory responses to CO2or in VE57. The presence and magnitude of these changes were unrelated to pre-existing mechanical or gas-exchange abnormalities.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The cardiovascular effects of 3 and G per cent alveolar concentrations of diethyl ether in nine healthy young volunteers during the first and fifth hours of anesthesia were studied. Pac*was maintained at 35–39 torr and esophagcal temperature at 36 ± 0.5 C. Cardiac output was unchanged or increased at 3 and 6 per cent ether during the first hour; heart rate increased while stroke volume fell. During the fifth hour of anesthesia, cardiac output increased at both 3 and 6 per cent ether, heart rate increased further, and stroke volume rose to the awake value. Total peripheral resistance was initially unchanged but fell with duration of anesthesia. The ratio of cardiac output to oxygen consumption was unchanged at one hour and increased at five hours. Base excess fell slightly initially and slightly more by five hours.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The cardiovascular effects of halothane, fluroxene, ether and cyclopropane in man during conditions of constant body temperature and Paco2and without concomitant surgical stress were compared. During the first hour of anesthesia, all anesthetics elevated mean right atrial pressure, increased skin blood How and decreased base excess and oxygen consumption. Ether, fluroxene and cyclopropane allowed cardiac output, stroke volume, left ventricular work and stroke work and mean arterial pressure to remain near or above control (awake) values, whereas halothane decreased all these values. Longer durations of anesthesia produced cardiovascular stimulation. After four to five hours of anesthesia, mean right atrial pressure decreased from the values at one hour to or toward control values, while cardiac output, heart rate, stroke volume, left ventricular work and oxygen consumption tended to increase. Total peripheral resistance decreased, while arterial pressure remained constant or decreased at lighter levels of anesthesia. The cause of the stimulation associated with duration of anesthesia remains unknown.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

An atmosphere of 80 vol per cent nitrous oxide and 20 vol per cent oxygen produced erythropoietic and leukopoietic depression in rats in the first two days of a six-day exposure. The depression was rapidly reversed by return to room air.56Fe and21C-thymidinc distribution studies indicate that hematologic depression occurs at the hematopoietic stem cell or an alternate progenitor cell level. The diminished erythropoietic response to erythropoietin of rats breathing nitrous oxide provides further evidence for this contention. Lymphocytes were relatively resistant to nitrous oxide. Electron spin resonance (ESR) measurements revealed increased free radicals in the liver, whereas levels in the spleen and marrow were too low to measure. Fasting produced similar changes. When animals exposed to nitrous oxide were fasted the free radicals in the liver decreased to levels lower than those in fasted control animals and paralleled the hematopoietic changes. These results suggest that nitrous oxide acts at the level of the hematopoictic stem cell to arrest hematopoicsis, an effect which is rapidly reversible with return to room air. No definite causal relationship between ESR changes and the hematologic changes induced by nitrous oxide could be established.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID