摘要:

AbstractThe effects of hexobarbital, pentobarbital, methohexital and thiopental (0.5 mil and 2 mM) on the synthesis and fast axonal transport of3H‐leucine‐labeIled proteins were studiedin vitroin the sciatic system of the frog. The methodology used made it possible to discriminate between effects on synthesis and transport. All 4 drugs arrested the transport, pentobarbital being the most, and thiopental the least, potent one. The transport inhibiting effect of 0.5 mil pentobarbital was reversible but not that of the higher concentration. These drugs, at concentrations (2 mM) which inhibited axonal transport, did not influence the uptake of3H‐leucine into ganglionic cell bodies, whereas pentobarbital, methohexital and thiopental, but not hexobarbital, depressed subsequent steps of protein synthesis. Pentobarbital lacked effect on protein synthesis at a concentration (0.5 mM), which arrested axonal transport by 50%. The results indicate that rapid axonal transport shows higher sensitivity than protein synthesis to the barbiturates tested. Fairly high concentrations of barbiturates were required to inhibit axonal transport and still higher to depress protein synthesis in the present study. Normal anesthesia by barbiturates is therefore hardly likely to affect these mecha

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05699.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractCats in thet postabsorptive state and anesthetized with chloralose where used for the experiments. In 7 out of 8 expts. ligation of the hepatic artery caused no change in the hepatic elimination rate of ethanol, the secretion rate of bile and Indocyanine Green (IGC), the hepatic oxygen consumption or the output of glucose and lactate, whereas a small decrease in hepatic ketone production was noticed. Ligation caused a 16 per cent decrease in ICG‐clearance and a 60 per cent increase in the extraction ratio of ICG, which can be explained by the reduction in total liver blood flow. In one experiment in which the initial hepatic oxygen consumption was relatively high ligation caused a fall in hepatic oxygen consumption with marked changes in liver function as a consequence. It is concluded that the main function of the hepatic artery is to supply the liver as a whole with oxygen whereas no specific functions of the artery were demonstrabl

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05700.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractYoung “prehypertensive” SHR were treated with two kinds of β‐adrenergic receptor antagonists from 2 1 / 2 up to 8 months of age. Arterial pressure largely remained at prehypertensive levels and acute cardiovascular responses to “stress” were considerably modified compared to untreated SHR. Quantitative hemodynamic analyses revealed that resistance vessel design exhibited only slight hypertensive changes when related to untreated controls, while the development of left ventricular hypertrophy was far less influenced by the treatment. In part of the group, pressure was followed for another 6 months after treatment, showing only a delayed and modest pressure rise compared with untreated, matched SHR. When instead adult SHR, with “established” hypertension, were similarly treated from 8 up to 10 months of age, resting arterial pressure remained unaffected and the resistance vessels exhibited only modest regression of the hypertensive changes, with signs of a largely preserved increase of vascular wall/lumen ratio, and with negligible regression of cardiac hypertrophy. The results indicate that early, “preventive” treatment of SHR with β‐receptor blockers is of considerable value whichever their exact modes of action, though some regression of vascular changes can be achieved also in established hypertension, particularly in

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05701.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractSingle motor units of the cat's inferior oblique muscle were isolated by partial denervation of the muscle and threshold stimulation of split motor nerve filaments. With electrical tests singly innervated (SI) units, multiply innervated conducting (MIC) units and multiply innervated non‐conducting (MIXC) units could be differentiated. SI units conducted impulse activity faster (2.93 m/s) than MIC units (1.72 m/s). Singly innervated units contracted faster than multiply innervated units. Fusion frequency was found the most useful parameter for a mechanical separation; most SI units fused above 200 pps, most MIC units between 100 and 200 pps and the MIXC units below 100 pps. Tetanic tension was higher in fast (SI) than in slow (MIC and MIXC) units, but there was a considerable overlap. The range for the whole material was 25–425 mg. In fast units fusion fequency and the rate of stimulation for maximal tetanic tension coincided. In slow units maximal tetanic tension was reached at stimulus rates of 150–200 pps irrespective of the fusion frequency of the unit. Resistance to fatigue was high in the slow units and in the majority of the fast units.The contractile properties fit into the motor unit activity pattern determined through motoneuron recordings in alert an

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05702.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractGlycogen depletion was followed in the soleus, gastrocnemius, and vastus lateralis muscles of 3 men during 2 h of treadmill running on the level and uphill (+6o). One subject also ran downhill (‐4.5o). Running speed was adjusted in each condition to require 75% of the subjects' Vo2max. Glycogen concentrations were similar in all 3 muscles at rest. From PAS staining glycogen appeared to be evenly distributed between slow and fast twitch fibres. A glycogen depletion of 17, 33, and 44 mmol of glucose units X kg‐1wet weight occurred in the vastus lateralis, soleus, and gastrocnemius muscles, respectively, after running on the level. These values were 55, 46, and 60 mmol X kg‐1, respectively, after uphill running. Glycogen depletion in the soleus and gastrocnemius muscles after downhill running was similar to that after running on the level, however, in the vastus lateralis it was intermediate to that for uphill and level running. A loss of PAS stain was observed first in the slow twitch fibres in all conditions. The results support the concept of a differential involvement of the leg muscles during running which can be modified by running either uphill or downhill. Thus it is of importance for the representativity of a sample that it is taken from a particular muscle when the local response to exercise or physical training is st

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05703.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractContractions of the stapedius and tensor tympani muscles were elicited by electrical stimulation of their motor nerves or of the muscles themselves in anesthetized cats. The effects of these contractions on cochlear microphonic responses to air‐ and bone‐conducted sound were examined. Stapedius contractions that produced changes in air conduction similar to those observed under physiological conditions had almost identical effects on bone conduction. Tensor tympani effects on bone conduction were of similar magnitude but greater complexity than those on air, and varied as a function of the location of the bone conductor on the skull. Control observations established that the effects were attributable to the middle ear muscles and not to other consequences of the experimental procedures, and that they did not reflect modification of an air‐conduction component of the bone‐conduction stimulus. The functional significance of these effects is discussed in terms of protection against masking of environmental sounds by self‐generated bone‐cond

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05704.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe “leakage” of proteins from plasma to interstitial fluid in burns was studied experimentally in dogs. The concentration of orosomucoid, α1‐antitrypsin, albumin, haptoglobin, IgG, β1C‐globulin and α2‐macroglobulin were determined in plasma and in lymph from the leg before and after scalding of the paw. The lymph/plasma ratio of all proteins except that of α2‐macroglobulin increased after scalding, indicating an increased capillary permeability to proteins with molecular weight

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05705.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractAn analysis was made of the effect of DDT and related substances on the membrane currents associated with step changes of the membrane potential. The substances tested are: DDT, DDD, DDE, DDMU, DDA, DDCN, bis‐(p‐chlorophenyl)‐acetamide and polychlormated bi‐phenyls (PCB). DDT. DDA and bis‐(p‐chlorophenyl)‐acetamide had acute effects on permeability parameters of the nerve membrane. The effects of the substances differed drastically from each other. DDT affected the turn off process of the sodium permeability mechanism after a positive potential step; the effect was large on fibres fromRana pipiensbut negligible on fibres fromXenopus laeris.DDA affected the turn off process of the potassium permeability mechanism while bis‐“p‐chlorophenyl‘‐acetamide affected sodium and potassium permeability constants, Pxaand PK. The other substance; tested had no or only marginal acute effects. The main effect of DDA may be described as a specific effect on the rate constant βn. The obvious differences in effects of the substances on the permeability parameters were thus related to defined minute molecular differences o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05706.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe time and potential dependence of the conductance process (es) underlying the longlasting afterhyperpolarization (AHP) in the cat's a‐motoneurones were studied. The conductance changes were determined by injection of short current pulses. The conductance time course was characterized by a longlasting exponential decay interrupted by a plateau corresponding to the slower hypcrpolarizing phase of the AHP. By displacing the membrane potential in the subthreshold region with the injection of longlasting current pulses it was found that the conductance was largely unaffected by membrane potential displacements. Similar characteristics were found when calculating the AHP conductance time course from the AHP voltage. It was concluded that the AHP in motoneurones is given by a potassium conductance process with this complex S‐shaped time course. A mathematical expression describing this time course is gi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05707.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe firing behaviour of a neurone model, in which the refractoriness is solely governed by a longlasting potassium conductance process with a time course similar to that underlying the afterhyperpolarization in a‐motoneurones (Baldissera and Gustafsson 1974 a) is described. The frequency‐current relation in the model is shown to display the 3 firing ranges found in real motoneurones (Kernell 1965 b, Schwindt 1973). With increasing current injection the inter‐spike voltage traJectories in the model are also undergoing the same peculiar modifications as described for real motoneurones (Schwindt and Calvin 1972, Schwindt 1973). A re‐examination of the first interspike interval in real motoneurones revealed earlier not recognized firing behaviour predicted by the mode]. It is concluded that the model is well simulating the firing behaviour of the first interspike interval in a‐mot

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05708.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY