ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Plasma renin activity (rate of angiotensin I generation) does not increase during anesthesia with ketamine, fluroxene, halothane or enflurane in the sodium-replcted rat. However, blood pressure decreases when an angiotensin II antagonist, saralasin, is administered during halothane or enflurane anesthesia, but not during ketamine or fluroxene anesthesia. Differences in the rates of conversion of angiotensin I to angiotensin II induced by various anesthetic agents could help explain these previous findings. To determine the effects of anesthetic agents on angiotensin I conversion, experiments were performed invitroandin vivo.The activities of rabbit pulmonary converting enzyme in the presence and absence of halothane or fluroxene were measured as rates of appearance of the dipeptide, histidyl-leucine, a product of angiotensin I hydrolysis to angiotensin II. Halothane and fluroxene did not alter conversion.Infusions of angiotensin I and angiotensin II were given to Wistar rats to construct dose-blood pressure response curves. The animals were then anesthetized with ketamine or halothane and infusions were repeated. Angiotensin I and angiotensin II induced similar blood pressure responses in awake and anesthetized rats. However, ketamine accentuated the pressor responses to angiotensin I and angiotensin II, whereas halothane depressed the responses. With the anesthetic agents studied, there is no significant effect on conversion of angiotensin I to angiotensin II either invitroor invivo.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Effects of controlled subanesthetic concentrations of enflurane on short-term memory functions and associated scalp evoked potentials were studied in eight male volunteers. Short-term memory processes were assessed through a search task. A series of digits (one, three, five, seven, nine, or 11 digits in each series) was presented visually, followed by a test digit, which in half of the trials was part of the series, and in half of the trials was not. The subject responded by pressing one of two switches, signalling “yes” or “no” accordingly. Averaged evoked potentials elicited by the test digit were obtained from seven sites on the scalp.End-tidal enflurane concentrations between 0.12 and 0.25 per cent increased significantly by 30–40 msec the latency of the components of the evoked potentials reflecting sensory processing, but did not affect their amplitude significantly. This increase could not explain the 287-msec increase in reaction time. Amplitude of late components of the averaged potential reflecting information processing was markedly decreased, which the authors interpret as indicating increased trial-to-trial variation in latency of the late component. The authors conclude that enflurane delays and introduces variance into the short-term memory processes and subsequent decision processes that precede overt responses.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The response of the human peripheral circulation to morphine in large doses independent of cardiac and respiratory influences has not been delineated. In 28 patients during cardiopulmonary bypass, alterations of peripheral vascular resistance (PVR) and capacitance in response to rapid arterial injection of morphine, 0.5 mg/kg or 1 mg/kg alone, or preceded by promethazine, 1 mg/kg, naloxone, 10 μg/kg, or naloxone, 20 μg/kg, were recorded over 15 min at a constant perfusion rate. Both doses of morphine decreased PVR by 46 per cent at 2 min, with values returning to control at 9 min. When promethazine preceded morphine, the decrease in PVR after morphine was 25 per cent. Naloxone did not alter the response. An increase in capacitance of 600 ml observed 5 min after morphine administration did not revert to control after 15 min, and was unaltered by prior administration of naloxone.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Isolated guinea pig nerve-lumbrical muscle preparations were exposed to halothane, methoxyflurane, isoflurane, enflurane, fluroxene, and diethyl ether. The temporal courses of the effects on indirectly and directly elicited twitch responses were determined over a range of concentrations for each agent. When the anesthetics were compared at concentrations equivalent in terms of minimum alveolar concentration (MAC), a spectrum was observed in which halothane, methoxyflurane and isoflurane depressed the indirect twitch response at 3.5–5 MAC and the direct twitch response at 8–10 MAC. Diethyl ether and fluroxene depressed the indirect twitch response at 2–3.5 MAC and the direct twitch response at 3–6 MAC. Enflurane depressed the indirect response at 1.5–2.5 MAC and the direct response at 6–8 MAC. When the anesthetics were compared at concentrations equivalent in terms of their abilities to depress end-plate depolarization, however, all anesthetics were equipotent. Depression of the indirect twitch response occurred only when anesthetic concentrations were great enough to depress depolarization by 50 per cent.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The microvascular effects of sodium nitroprusside (SNP) were studied in rat striated muscle to determine the peripheral vascular sites of action of the drug. Eleven male rats were anesthetized with pentobarbital and the cremaster muscle was prepared for television microscopy. The internal diameters of three arterioles and two venules of each animal were measured before) during and after SNP infusion (40 μg/kg/min). First-order arterioles (123 ± 7 μm) showed no significant response to SNP, and their internal diameters correlated poorly (r = −0.31) with decreases in mean arterial pressure (MAP). The internal diameters of third-order arterioles (42 ± 2 μm) correlated well with MAP (r = 0.85), but these arterioles did not dilate significantly during SNP infusion. The internal diameters of fourth-order arterioles (15 ± 1 μm) correlated best with MAP (r = 0.91), and significant (P < 0.05) dilatation occurred promptly during SNP infusion. Thereafter, the responses of fourth-order arterioles could be divided into two subgroups. One subgroup dilated initially but promptly returned to control diameters, while the other subgroup remained dilated (P< 0.05) throughout exposure to SNP. Both third- and fourth-order arterioles constricted significantly when SNP infusion was discontinued. Venular diameters were not affected by SNP. In five additional rats, topical application of SNP (10-4M) to the cremasteric microvasculature resulted in dilatation of fourth-order arterioles, which persisted throughout exposure to SNP, but reverted to control diameters when the drug was removed. The transient dilatation of some fourth-order arterioles, and the arteriolar constriction observed when intravenous infusion of SNP was terminated, appear to represent compensatory responses to hypotension, since these effects were not seen with topical application of SNP. The results indicate that the primary peripheral vascular site of action of SNP is in fourth-order arterioles.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The use of procainamide or procaine for treatment of malignant hyperthermia is commonly recommended. The skeletal muscle relaxant dantrolene has also been indicated for treatment of this complication during anesthesia. In the present study, effects of procainamide and dantrolene were compared in malignant hyper-thermia-susceptible (MHS) pigsin vivoand on MHS muscle from human patientsin vitro.The ED50for dantrolene block of indirectly evoked twitch tension was 0.85 mg/kg in MHS pigs. A final cumulative dose of 2 mg/kg resulted in 68 per cent block of the twitch response. In contrast, procainamide at a final cumulative dose of 14 mg/kg had no effect on twitch response of the MHS pigs. Dantrolene, 3 μM,in vitro(approximately 0.8 mg/kgin vivo)was effective in preventing or reversing the abnormal halothane-induced contracture response of human MHS muscle strips. Procainamide, 0.11 mM, a dose approximating clinical levels (about 22 mg/kg), had no effect on basal twitch response or on the abnormal halothane-induced contracture of MHS human muscle. These results confirm the effectiveness of dantrolene and the lack of effectiveness of procainamide in the treatment of malignant hyperthermia.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Other investigators have demonstrated halothane-induced hepatic injury in rats anesthetized in hypoxic environments. The authors examined this phenomenon in mice and investigated plasma fluoride levels in mice and rats anesthetized with halothane in 40, 21, and 7 per cent oxygen with or without pre-treatment with phenobarbital or carbon tetrachloride. They found no hepatic necrosis in mice. Mice produced less fluoride than rats. This difference in halothane metabolism between Sprague-Dawley rats and Swiss-Webster mice may explain the failure to observe hepatic necrosis in mice.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Halothane-induced changes in renal function have generally been attributed to alterations in systemic hemodynamics, sympathetic tone, and various hormones. Studies were performed to determine whether halothane directly affects the kidney. Twenty-one canine kidneys were perfusedin vitroutilizing hemodilution, pulsatile flow, and membrane oxygenation. Temperature and arterial blood-gas variables were controlled and mean and pulse pressures were maintained. Four experimental periods (I-IV) (each consisting of two 10-min sample collection periods) were conducted, with a 20-min “rest” period between succeeding experimental periods (elapsed time = 140 min). Responsiveness was assured by obtaining a normal response to furosemide, acetylcholine, or epinephrine after Period IV. In eight additional kidney preparations halothane was administered to achieve either a “low” (17 + 3 mg/100 ml) or “high” (35 ± 5 mg/100 ml) concentration in Period II, the sequence reversed for Period III, and halothane eliminated by Period IV. Halothane produced marked increases in blood flow (21–26 per cent), total (203–267 per cent) and fractional (173–179 per cent) sodium excretion, osmolal clearance (62–111 per cent) and urinary volume (130–161 per cent). These changes were associated with a shift of microspheres from outer to inner cortex, and were completely reversible by eliminating the halothane. In the absence of external influences, halothane produces renal vasodilation and natriuresis. Direct tubular depression cannot be ruled out.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID