ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Interactions of neuromuscular effects of edrophonium, alphabungarotoxin, and beta-bungarotoxin were studied in 12 chickens using the sciatic-gastrocnemius nerve-muscle preparation to elucidate the mechanism of action of each drug. Modification by the toxins of neuromuscular effects of edrophonium depended on the level of block pre-established by the toxins. Edrophoniuminduced augmentation of muscle twitch (“facilitation”) was decreased by both toxins. As the block reached 50 per cent, the facilitation was nearly abolished. Edrophonium-induced contracture of the muscle was blocked by alpha-bungarotoxin only. At 25 per cent block, it was no longer observable in five of six preparations. Beta-bungarotoxin enhanced the contracture. At complete block, the contracture reached 156 (SE 11, n=6) per cent of control. The authors conclude that edrophonium facilitates neuromuscular transmission by a prejunctional mechanism and causes contracture of the chicken muscle by a postjunctional activation. The beta-bungarotoxin-blocked nervemuscle preparation of the chicken is a model of acute denervation potentially useful for the study of drug effects on the postjunctional membrane.

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Ketamine has been demonstrated to inhibit norepinephrine uptake in the adrenergic neuronal membrane, an action similar to that of cocaine. This study evaluated possible potentiation of five vasoactive amines, norepinephrine, epinephrine, tyramine, dopamine, and isoproterenol, by ketamine in the isolated rabbit heart at 35, 30, 25 and 20 C. The hearts were perfused with one of the vasoactive amines alone, ketamine (500 Mg/ml) alone, and combinations of ketamine with the amines, in random order. Heart rate, left ventricular dP/dt, and left ventricular systolic, diastolic, and mean pressures were recorded.Heart rate was decreased by ketamine alone; this effect became less significant with increasing hypothermia. No significant change from control was observed at 25 or 20 C. Heart rate increased significantly during perfusion with ketamine plus norepinephrine, epinephrine, or tyramine compared with control, and during perfusion with these amines alone at 35 C. The potentiation of heart rate caused by ketamine plus norepinephrine compared with norepinephrine alone was not affected by cooling to any temperature, while the difference between extents of potentiation by epinephrine or tyramine with and without ketamine decreased with cooling, becoming insignificant at 25 C or less.Dopamine and isoproterenol produced greater increases of heart rate alone than when perfused with ketamine, the differences becoming less with cooling.Left ventricular dP/dt was significantly decreased by ketamine alone, this effect becoming less apparent with cooling. Ketamine combined with norepinephrine, epinephrine, tyramine, isoproterenol, or dopamine significantly increased dP/dt over control, while only ketamine combined with norepinephrine, epinephrine, and tyramine significantly increased dP/dt compared with these vasoactive amines alone. Potentiation of left ventricular dP/dt by ketamine plus epinephrine or tyramine (compared with these amines alone) became less apparent with cooling. When ketamine was combined with norepinephrine, however, similar extents of potentiation were observed at all temperatures compared with norepinephrine alone.Ketamine plus isoproterenol or dopamine decreased dP/dt compared with the amines alone at 35 C, this effect becoming less apparent with cooling. These results indicate that ketamine, like cocaine, may be a catecholamine Uptake 1 inhibitor.

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

5.52 x 102 mm Hg/ml/min/ kg), and mean aortic pressure (MAP) (94 —> 80 —> 69 mm Hg) were accompanied by increased left ventricular end-diastolic pressure (LVEDP) (11 —> 12 —> 14 mm Hg), without change in heart rate or systemic vascular resistance (SVR). Preload (LVEDP) and afterload (MAP and SVR) changes could not account for the demonstrated depression in ventricular function. Thus, in man, as in the dog, halothane has a direct depressant effect on LV function.

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Hepatic drug-metabolizing enzymes and hepatic ultrastructure were studied in rats after two hours of anesthesia with 1 MAC halothane or diethyl ether. Twelve hours after cessation of either anesthetic smooth endoplasmic reticulum was increased in centrilobular but not in periportal hepatocytes. This change persisted at 24- and 36-hour sampling times. Microsomal cytochrome P.,r,,i and cytochrome b., decreased after halothane anesthesia (by 7 to 20 per cent of control). Diethyl ether caused increased cytochrome P.r.o and cytochrome b-, (27 and 18 per cent, respectively) at the 36-hour sampling time. NADPH cytochrome c reductase did not change significantly after either agent. The authors interpret these results to mean that both agents promote conversion of rough endoplasmic reticulum to smooth endoplasmic reticulum or, alternatively, that the anesthetics decrease degradation of smooth endoplasmic membranes. Since only ether caused an increase in the microsomal content of enzymes of the drug-metabolizing enzyme system, it is concluded that these two anesthetics act on hepatic cells by dissimilar mechanisms

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

This experiment was designed to determine the microvascular responses to the two known naturally occurring vasoconstrictors, norepinephrine (NE) and vasopressin, at known levels of central vasomotor activity before, during and after halothane anesthesia. The responses to topical application of NE and vasopressin were studied in the microvascuiatUre of the mesentery and cremaster muscle, using microscopic methods. Neural (CNS) stimulation was accomplished through electrodes chronically implanted in vasoactive sites of the forebrain and midbrain. The increase in blood pressure in response to CNS stimulation was decreased during halothane anesthesia (32.4 ±5.4 per cent before and 24.7 ±6.1 per cent during; P<0.001). There was no significant change in the steady-state diameter of the microvasculature under study during or after halothane anesthesia. Marked abatement of arteriolar vasoconstriction in response to CNS stimulation was seen prior to halothane. However, the same target vessel showed increased constriction in response to topically applied NE (from 32.3 ± 4.7 to 53.2 ± 7.8 per cent; P<0.01) during halothane anesthesia. By contrast, the response to vasopressin decreased (from 42.4 ± 5.7 to 1.0 ± 6 per cent; P<0.001) with halothane. The precise mechanism(s) underlying the described hypersensitivity to NE and hyposensitivity to vasopressin in the same vascular structure during halothane anesthesia remains undetermined

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The levels of14C-glycopyrroIate, a quaternary ammonium anticholinergic agent, appearing in cerebrospinal fluid (CSF) and serum (S) following a single intravenous dose of 0.1 mg/kg were determined in mongrel dogs during barbiturate anesthesia and compared with levels reached in dogs treated with similar doses of: lH-atropine. Presence of each anticholinergic drug in the peripheral circulation was confirmed by antagonism of the depressor response to intravenously administered acetylcholine. Ten minutes after drug injection, CSF levels of °H-atropine averaged 10.3 ± 3.1 ng/ml, whereas14C-glycopyrrolate CSF levels were restricted to 0.9 ± 0.4 ng/ml. Peak CSF/S concentration ratios for 3H-atropine averaged 0.87, vs. a mean ratio of 0.1 for14C-glycopyrrolate within the four-hour observation period. Peripheral anticholinergic activity produced by glycopyrrolate was of the same order as that seen with the equivalent dose of atropine. In pregnant barbiturate-anesthetized dogs peak mean fetal serum (FS) levels of 13 ± 1.5 ng/ml occurred 10 min after a single intravenous dose of 0.1 mg/kg 3H-atropine administered to the mother, and represented 30 per cent of the corresponding maternal serum (MS) concentration.14C-Glycopyrrolatetreated dogs showed peak mean FS levels of 0.63 ± .07 ng/ml four hours after administration. The maximum FS/MS concentration ratio observed within the four-hour post-drug period for '''H-atropine was 1.0, vs. 0.04 for14C-glycopyrrolate. Anticholinergic effects in the mother were significantly greater with glycopyrrolate than with identical doses of atropine. These studies show that glycopyrrolate is a selective peripheral anticholinergic agent, in that it is more resistant than atropine to penetration across the blood—brain and placental barriers.

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Cardiovascular effects of nitrous oxide during enflurane anesthesia were studied in 12 healthy, young volunteer subjects ventilated to maintain normal PaC0]. Twelve circulatory variables were measured and 13 more calculated. When nitrogen, 70 per cent, was added to enflurane, 1.86 per cent (1 MAC), or enflurane, 2.93 per cent end-tidal, no change was observed. When nitrous oxide, 70 per cent, was added, only minimal changes were observed. In a second part of the study, enflurane was compared with enflurane-nitrous oxide, 70 per cent, at equipotent levels. The following three variables (in percentages) decreased less in relation to awake control values at 1 MAC enflurane-nitrous oxide-oxygen than at 1 MAC enflurane-oxygen: left ventricular stroke work, -47.2 vs. -55.9; aortic dP/dt, -44.0 vs. -57.1; pressure- pulse product, -26.6 ns. -39.4. Forearm venous compliance decreased more: -26.0 vs. 2.9. The difference between the anesthetic mixtures was much more noticeable at 1.5 MAC, where eight variables (in percentages) decreased less with enfluranenitrous oxide-oxygen than with enflurane-oxygen: cardiac output, -6.9 vs. -22.1; stroke volume, -31.4 ns. -46.0; left ventricular minute work, -32.6 vs. —49.6; left ventricular stroke work, -50.8 vs. -65.8; left ventricular stroke power, -48.2 us. -63.1; ballistocardiogram, -34.5ns. -49.1; aortic dP/dt, -49.7ns. -65.8; pressure-pulse product, -32.3 vs. -42.3. Heart rate increased less when nitrous oxide was included in the mixture: 34.5 ns. 43.6. The lack of response during the addition of nitrous oxide to enflurane-oxygen is contrary to the significant sympathomimetic response seen when nitrous oxide is added to halothane, fluroxene, or diethyl ether. The apparent protection afforded by nitrous oxide at equipotent anesthetic levels is small enough that the main consideration in choosing between the two mixtures should be the concentration of oxygen needed by the patient.

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Elective cesarean section was performed in a consecutive scries of 30 patients with full-term pregnancies who were not in labor. Epidural (lidocaine, 1.5 per cent, with epincphrine, 1:200,000) and general anesthesia (thiopental, nitrous oxide-oxygen, succinylcholine infusion) was used alternately. Neonatal acid-base values and Apgar scores showed no significant difference between the two anesthetic groups, and most infants were vigorous at birth. The neurologic recoveries of the infants showed no significant difference between the two groups. In the group receiving epidural anesthesia, there was a significant correlation between maternal hypotension and weak rooting and sucking reflexes of the infants during the first two days. All infants of high-risk obstetric patients in the series, independent of anesthetic technique used, had abnormal neurologic activity, as evidenced by either depression of muscle tone and the reflexes or all the tested variables. Neurologic assessment as followed in this series is a sensitive indicator of the effects of fetal stress factors acting during cesarean section.

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1978

数据来源: OVID