摘要:

AbstractA study was made of the accumulation of the monoamines, 5‐hydroxytryptarnine and noradrenaline, by phospholipid vesicles of similar chemical composition to the natural monoaminr storage vesicles. Although the artificial vesicles would accumulate the monoamines against a concentration gradient they were far inferior in this respect to the natural vesicles. The accumulation of the monoamines was studied as a function of time, temperature and the chemical composition of the vesicles, and the effect of osmotic shock, reserpine, metaraminol and calcium on the release of the monoamines was noted. The results indicated that the binding of 5‐hydroxytryptamine was increased by acidic phospholipids but that noradrenaline was unaffected. A temperature rise only marginally inreased the monoamine accumulation. Reserpine slightly retarded the release of noradrenal

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05567.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe degeneration of the terminal network of sympathetic nerve fibres in the rabbit uterus and oviduct were studied after treatment with 6‐OH‐Dopamine. The majority of the fluorescent fibres of the myometrial smooth muscle disappeared 24 h after the treatment. The recovery of the fluorescence required 4–7 weeks. At the finestructural level, no adrenergic axon terminals could be identified while the nonadrenergic axons and axon terminals seemed intact. Complete adrenergic denervation caln be achieved by the use of 6‐OH‐dopamine also in those regions, which are innervated through the “short adrtnergi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05568.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe effects of lanthanum on the electrical and mechanical activities of isolated muscle fibres from the frog were investigated. Lanthanum, in the range 0.05–0.3 mM, produced characteristic, concentration dependent changes of the isometric twitch. There was an increase in latent period, increase in rate of tension development, potentiation of peak twitch amplitude, and a prolongation of the relaxation period. Lanthanum produced no change of the resting potential, hut caused a graded reduction in rate of rise, amplitude, and rate of fall of the action potential. At concentrations of the metal ion exceeding 0.3 mM, the mechanical response was complicated by impaired excitation, leading to a diminution of the twitch response and failure to produce a fused tetanus. Exposure to still higher concentrations of lanthanum (≥ 0.5 mM) made the fibre electrically inexcitable. The lanthanum‐induced changes were completely reversible on removal of the metal ion from the bath. Lanthanum in a concentration of 0.1 mM could be used as a substitute for calcium to maintain a normal resting membrane potential and twitch response. The results suggest that lanthanum and calcium act on a common site in the membrane. The alterations in twitch kinetics produced by lanthanum are discussed in relation to changes of action potential and mechanical thre

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05569.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe effects of lanthanum on the time course of potassium‐induced contractures of isolated muscle fibres from the frog were investigated. Two kinds of effects could be distinguished: 1. A reduction in the rate of tension development and a decrease in contracture amplitude; 2. A prolongation of the tension plateau and a decrease in the rate of relaxation during sustained depolarization. The effects under point 1 were obtained at lanthanum concentrations ≥ 0.5 mM, while those under point 2 were clearly visible at lanthanum concentrations as low as 0.01 mM. In a calcium‐free medium containing 0.1 mM lanthanum, a muscle fibre produced repeatable contractures to 117.5 mM potassium over many hours. The slowing of tension development and the diminished contracture amplitude is explainable on the basis of a reduction in the rate of release oi activator calcium in response to a depolarization step. The prolongation of the platmu and the slowing of relaxation caused by lanthanum is interpreted as reflecting a reduced rate of inactivation of thc calcium‐release mechanism following depolar

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05570.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe effects of insulin (0.1 U/ml) on the glucose metabolism in vascular and intestinal smooth muscle are weak in comparison with those in skeletal muscle and also appear later (Arnqvist 1973). In this study insulin (0.1 U/ml) was found to stimulate the membrane transport of α‐aminoisobutyric acid‐14C (AIB‐14C) and the incorporation of leucine‐14C into protein in bovine mesenteric arteries and rabbit colon smooth muscle. Also these effects were weaker and appeared later than the corresponding effects in skeletal muscle. The dose‐response curves for the accumulation of glucose‐14C and the incorporation of leucine‐14C into protein in bovine mesenteric arteries were both displaced to the right in comparison with those for rat diaphragm. Blocking protein synthesis by puromycin did not abolish the effect of insulin on the accumulation of glucose‐14C. The sensitivity of bovine mesenteric arteries to the effect of insulin on the accumulation of glucose‐14C did not increase during the incubation period. The finding that all the diverse effects of insulin on smooth muscle were weaker and appeared later than those in skeletal muscle may indicate that they are initiated by a common receptor mechanism which differs in smooth muscle a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05571.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractCarbonic anhydrase activity in the corneas of adult man, human fetus, monkey, rabbit, rat, cow, pig and American bullfrog was examined by the histochemical method of Hansson. In all species the endothelial cells were intensely and distinctly stained for carbonic anhydrase activity. The enzyme inhibitor acetazolamide at 10‐‐5M in the incubation medium completely, and at 10‐‐6M almost completely, inhibited the staining. There was no staining in other parts of the cornea with the possible exception of a few cells in the frog epithelium. Endothelium, epithelium and stroma of cow and rabbit corneas were dissected and homogenized. The carbonic anhydrase activity was determined by a changing pH, indicator method. Only the endothelium showed activity and this was sensitive to inhibition by acetaz

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05572.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractIn the superfused guinea pig vas deferens, prostaglandin E2(1–10 ng/ml) caused a dose dependent and reversible depression of the overflow of3H‐noradrenaline in response to trans‐mural stimulation. Increasing the calcium concentration in the superfusion medium from 1.8–5.4 mM enhanced the overflow of3H‐noradrenaline and reversed the inhibitory effect of prostaglandin E2. Closely similar effects were obtained with prostaglandin E1. In the presence of elevated calcium (5.4 mM), prostaglandin E2was still inhibitory, but the dose‐effect curve was significantly shifted to the left, making the compound less effective in inhibiting the overflow of3H‐noradrenalhe. The results are compatible with, and add further weight to the consideration that prostaglandins of the E series restrict the release of noradrenaline from sympathetic nerves by inhibiting the influx of calcium ions in

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05573.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractPhenoxybenzamine, hydergin and phentolamine, all markedly increased the overflow of3H‐nor‐adrenaline in response to transmural stimulation of the guinea pig vas deferens. After phannacological blockade of neuronal and extraneuronal uptake of noradrenaline, and after inhibition of local prostaglandin formation, the three compounds were still effective and caused increased overflow of3H‐noradrenaline. This effect was abolished by prostaglandin E2. Using the same pharmacological blockade, noradrenaline and methoxamine inhibited stimulated overflow of“H‐noradrenaline in a dose‐dependent manner. It is concluded that the activity of α‐receptorsPer secan feed back regulate the release of noradrenaline from sympathetic nerves. The possibility that the receptors are presynaptically located and that they act on Ca++influx into the neuro

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05574.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe convergence of inhibition and excitation from muscle spindle Ia and Golgi tendon organ Ib afferents was investigated in ventral spinocerebellar tract (VSCT) neurones monosynaptically excited from Ib afferents. Although most cells received Ib excitation from several nerves, the dominating excitation was supplied from nerves to synergistic muscles acting as either flexors or extensors at one joint. Disynaptic Ia lPSPs from the nemc to the knee extensor were common in cells with their main Ib excitation from the nerves to either hip, knee or ankle extensors or to knee flexors. The Ia IPSPs in cells excited from hip extensors and knee flexors were depressed by antidromic impulses in motor axons, while no such effect occurred on Ia IPSPs in the other cells. The Ia IPSPs in Ib VSCT neurones thus seem to be mediated by two different groups of Ia inhibitory interneurones, with and without recurrent inhibition from motor axon collaterals through Renshaw cells. Disynaptic Ib IPSPs from nerves to thigh muscles were rare while presumed Ib IPSPs from nerves to ankle and toe muscles were more common. In some cells there were indications of convergence of monosynaptic EPSPs and disynaptic IPSPs from Ib afferents in the same nerve. The results are discussed in relation to the hypothesis that the VSCT relays information about interneuronal transmission in the spinal cord.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05575.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractThe cortical irresponsive and recovery times were tested in albino guinea pigs and in ground squirrels with the same brief (1 ms) colored flashes and using the same anesthesia, dial. The irresponsive time was much longer, 60–80 ms, in the guinea pig compared with 15–20 ms in the squirrel. In the squirrel the retinal was at least 5 ms shorter than the cortical recovery time, and the retinal response reached 50 % of full amplitude when 25 ms separated the flashes compared with 100 ms for the cortical response. Since the conditioning and testing flashes had the same intensity, the irresponsive time diminished with decreasing strength of light until close to threshold in the guinea pig. The threshold was high in squirrel and flashes of maximum intensity were used with color filters. There was no difference between responses to colored flashes when the amplitude of the responses was the same, either in guinea pig or squirrel. In the guinea pig chloralose‐urethane anesthesia resulted in a longer irresponsive time, and with some light intensities there was a period when the response to the testing flash was larger than to the first flash, as has been described i

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1974.tb05576.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY