ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00899.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:A correlation of mercury absorption with water absorption was investigated by using the perfusion of rat small intestine with buffers containing 10−4M HgCl2. With a decrease in the osmolarity of the buffers or with increases in the sodium ion and urea concentrations in the buffers, absorption of water and mercury and accumulation of mercury in the intestinal tissue increased, and the increases in mercury absorption and accumulation were found to correlate with the increase in water absorption. Both the decrease in osmolarity and the increase in sodium ion concentration increased mercury accumulation in the epithelial cell after the perfusion. But these changes did not alter the mercury distribution in subcellular fractions. The results suggest that the increase in water absorption due to the hyptonicity or the increase in concentration of sodium ion or urea increases the mercury absorption and accumulation in the epithelial cell without change in the distributional pattern of mercury in the cel

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00900.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The pharmacokinetics of chloramphenicol (CAP) were studied in four colostrum‐deprived and 4 colostrum‐fed newborn piglets after an intravenous bolus dose of CAP, 77 μmol kg−1(25 mg kg−1). The elimination half‐lives in the colostrum deprived piglets had a tendency to be longer (17.2 ± 3.9 hrs) than in the colostrum‐fed piglets (12.7 ± 1.1 hrs) and in both groups they were considerably longer than reported in older pigs. The long half‐lives of CAP in the newborn pigs were a reflexion of very low clearance (Cl) values, 0.0391 ± 0.007 and 0.0512 ± 0.007 1 kg−1hr−1, in the two groups, while the volume of distribution was of the same size in the two groups, 0.9549 ± 0.247 and 0.9411 ± 0.211 1 kg−1. The protein binding of CAP in pooled piglet plasma was concentration dependent, 53–45%, (P<0.001) in the concentration range 31–232 μM (10–75 μg ml−1) and the binding degree was significantly higher in plasma from colostrum deprived piglets, 53.0 ± 0.8% compared to plasma fro

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00901.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The aim of the present study was 1) to characterize qualitatively the positive inotropic effect of the Ca‐channel activator BAY K 8644 and to compare this response to response‐types with known and different relationship to the cyclic AMP (cAMP) system (e.g. responses elicited through α‐ and β‐adrenergic receptor stimulation) and 2) to study the effect of simultaneous muscarinic cholinergic stimulation upon the BAY K 8644 response in order to further evaluate the role of the cAMP system in this response. The responses were evaluated in isolated, electrically paced, isometrically contracting papillary muscles from rat heart. Isometric tension (Tmax), rate of rise and decline of tension (first derivative = T′) and rate of transition from tension rise to tension decline (negative part of second derivative = T”) were recorded. In the presence of the α1‐adrenergic receptor blocker prazosin (10−7mol/l) and the β‐adrenergic receptor blocker timolol (10−6mol/l), the positive inotropic effect of 1.7 × 10−6mol/l BAY K 8644 developed rather slowly with a time to half maximal effect of about 4 minutes. Qualitatively the response was characterized by an almost proportional (“symmetrical”) increase in all parts of the contraction‐relaxation cycle with a small prolongation of time to peak tension and of the duration of the whole cycle. This response contrasted sharply with the cAMP‐dependent response to β‐receptor stimulation (β‐type response with shortening of time to peak tension), but was very similar to the cAMP‐independent response to α‐receptor stimulation (α‐type response). Additional cholinergic muscarinic stimulation by carbacholdid notcounteract the effect of BAY K 8644, but rather increased the inotropic response. It is concluded that both the qualitative characteristics of the BAY K 8644 response and the effect of simultaneous cholinergic stimulation upon this response are those expected for a cAMP‐independent response. The results also support the assumption that the response type can be used as a first step in classifying whether an inotropic agent is dependent

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00902.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The 7‐ethoxycoumarin and 7‐ethoxyresorufin O‐deethylase activities were investigated in the microsomal fractions from 5 human adult and 3 foetal livers and 5 human foetal adrenals. The enzyme activity expressed as pmol/min. per mg microsomal protein was higher with 7‐ethoxyresorufin as substrate in all investigated specimens with average values (± S.E.M.) of 74 ± 27, 13 ± 3 and 12 ± 1 in adult and foetal livers and foetal adrenals, respectively. Monoclonal antibodies raised against 3‐methylchloranthrene or phenobarbital induced rat liver cytochrome P‐450 were investigated with respect to their inhibiting effects on the rate of O‐deethylation of both substrates in human adult liver. Only the monoclonal antibody against the 3‐methylcholanthrene induced cytochrome P‐450 inhibited the O‐deethylation of 7‐ethoxyresorufin to 64 to 79 percent of control values. The other antibody had no effect on this or the other O‐deethylase activity. Thus, the 7‐ethoxyresorufin O‐deethylase is partly catalyzed in human adult liver by a cytochrome with an epitope that is recognized by the monoclonal antibody against 3‐methylcholanthrene induced rat liver cytochrome P‐450. With foetal liver the low activity of the enzyme became unmeasurab

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00903.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The mechanism of the anaesthetic effect of toluene on the central nervous system (CNS) was studied by using rat erythrocyte and synaptosome membranes as nerve cell models bothin vitroandin vivo.The activities of the membrane‐bound integral enzymes acetylcholinesterase (AChE), total adenosine triphosphatase (total ATPase) and magnesium‐activated adenosine triphosphatase (Mg2+‐ATPase) were determined. A short‐term exposure to 2000 p.p.m. of toluene had an inhibitory effect on the enzyme activities studied. The degree of inhibition in erythrocyte membranesin vitroandin vivo, and in synaptosome membranesin vitrowere in good correlation. Inin vivoconditions, the synaptosome‐bound enzymes were, however, significantly more inhibited by toluene, which indicates that membranesin vivoare even more vulnerable to the toxic effects of organic solvents than they are as isolated membranesin vitro.However, our results show thatin vitroexperiments can be used to predict the toxic nerve cell membrane effects of organic solvents. Toluene caused similar enzyme inhibitions both in neural cell membranes and in erythrocyte membranes. Thus, even peripheral non‐excitable cell membranes, like erythrocytes, can be used as nerve cell membrane models in studies on the mechanism of the anaesthesia caused

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00904.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The combined effect of terbutaline on systemic and coronary circulation was investigated in dogs to clarify its influence on myocardial oxygen supply and lactate balance. The dogs were anaesthetized and the chest opened. Coronary sinus blood flow and cardiac output were monitored by thermodilution, aortic pressure was measured by tip‐transducer and heart rate by RR‐interval on ECG, coronary sinus blood were analyzed for lactate, oxygen and carbon dioxide. Terbutaline caused a substantial systemic vasodilation and an increased heart rate, the total external cardiac work increased to a minor degree. Terbutaline increased arterial lactate concentration. Coronary vascular resistance was reduced after terbutaline. Even if myocardial perfusion pressure was reduced and an increased external cardiac work was present, no signs of myocardial distress was observed in lactate metabolism or coronary sinus oxygen content. In fact a tendency to increased myocardial aerobic metabolism was observed, as myocardial lactate consumption increased after terbutaline. Terbutaline seems to be a coronary vasodilator in dogs. However, the demand for oxygen secondary to both an increase in cardiac work and aerobic metabolism can be harzardous to the potentially ischaemic myocard

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00905.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:This paper investigates the effect of different storage conditions on the chemical stability, laxative effect and acute toxicity of sennoside solutions. The variables in storage conditions were pH, time and temperature (room temperature or 100°). The chemical stability of sennosides in aqueous solutions was found to be pH‐dependent, with the best stability at pH 6.5 (t90·=8.4 months) and the poorest at pH 8.0 (t90·= 2.5 months). Two years of storage at room temperature did not reduce the laxative potency in mice, regardless of the pH. After 4.25 years of storage the potency declined in alkaline solutions only. The degradation products with laxative potencies are chemically unknown. The acute toxicity of sennoside solutions increased with time during storage, the acid solution being more toxic than either the neutral or alkaline

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00906.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:Cholecystokinin (CCK)‐33 is known to stimulate insulin secretion. Presently, using the perfused rat pancreas, we have characterized the active site in the CCK‐33 molecule that is responsible for this effect by the use of different CCK fragments. We found that CCK‐33, CCK‐8 and CCK‐7 (1 nM) all significantly stimulated insulin secretion in the presence of 4.4 mM or 6.7 mM glucose. However, CCK‐7 was much less potent than the longer forms. In contrast, CCK‐4, CCK‐6 and CCK‐33 (1–21) had no effect on insulin secretion. We conclude that the shortest CCK‐form that stimulates insulin secretion at 1 nM is the C‐terminal heptapeptide CCK‐7. However, CCK‐8 is much more potent

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00907.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:Brown trouts,Salmo trutta, were exposed to water containing 0.1 or 10 μg/1 of63Ni2+, alone or with potassium ethylxanthate or sodium diethyldithiocarbamate. After one and three weeks the accumulation and disposition of the63Ni2+in the fish were examined by liquid scintillation spectrometry and whole‐body autoradiography. The sodium diethyldithiocarbamate was found to greatly enhance the uptake of63Ni2+in several tissues of the trouts. Potassium ethylxanthate was without effect. Diethyldithiocarbamate is known to form lipophilic complexes with metals, including nickel, and a facilitated penetration of the complexed nickel over the cellular membranes of the gills and other tissues is a likely mechanism underlying our results. The ethylxanthate is also able to form a lipophilic nickel‐chelate, although of a lower lipophilicity than the nickel‐diethyldithiocarbamate‐complex. This variance in lipophilicity may explain why the disposition of the63Ni2+was affected by the diethyldithiocarbamate, but not by the ethyl

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00908.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY