摘要:

AbstractIn acute experiments on chloralosed cats the effect of efferent cervical vagal stimulation on a flow through the ileo‐cecal sphincter (ICS) was studied. The motor activity of the jejunum, ileum and large intestine adjacent to the sphincter was recorded simultaneously. Vagal stimulation caused a decrease in the transsphincteric flow and increased motor activity in the ileum. Increased motor activity in the proximal colon was recorded only occasionally. When the vagal nerves were stimulated during continuous splanchnic stimulation the transsphincteric flow was decreased although the tone and motility of the ileum was supposed. Furthermore, guanethidine (1–3 mg/kg b.w.) blocked or suppressed the effect of vagal stimulation on the transsphincteric flow while the excitatory response of the proximal colon was greatly enhanced. This indicates that the reduction of the transsphincteric flow following vagal stimulation was at least partly due to a direct effect of the vagal nerves on the sphincteric muscle and not to a squeezing effect of that part of the colonic wall that surrounds the sphincter. Atropine (0.1 and 1 mg/kg b.w.) blocked all responses to vagal stimulation. Thus, both guanethidine and atropine blocked the vagally induced contraction of the ICS. Relaxation of the ICS was never obtained by vagal stimulation even when the tone of the sphincter had been increased by infusion of noradrenal

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10213.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractLanthanum chloride (≥ 10‐5M) induced pinocytosis in normal and at ≥10‐4M in Ca++‐deficient amoeba. With respect to the Ca++‐requirement of the pinocytotic response low and high concentrations of La+++had effects like Na+and K.+, respectively. The concentration of La+++and the concentration and species of inducing monovalent cation determined whether La+++stimulated or inhibited other types of pinocytosis. Thus all concentrations of La+++inhibited sodium induced pinocytosis while high concentrations (>10‐3M) stimulated and low concentrations diminished potassium induced pinocytosis. Only the latter effect required the presence of Ca++. In the presence of La+++other inducers acted either like K+or Na+. Inducers may cause channel formation by opening a pore for Ca++in the plasma membrane, Na+‐like inducers being less effective than K+‐like inducers, and by releasing Ca++into the cytoplasm from the glycocalyx (Na+‐like inducers) or from the entire cell membrane (K+‐like inducers). La+++may diminish the effect of Na+‐like inducers and vice versa by direct competition for sites in the glycocalyx and the effect of K+‐like inducers by redistribution of Ca++in the cell surface. At high concentrations or in the presence of a K+‐like inducer La+++may enter the Ca++pore, release Ca++from the interior of the membrane and so indu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10214.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractUltraviolet (UV) irradiation (4000–10000 erg × mm‐2) decreased membrane potential and input resistance ofAmoeba proteusand induced formation of pinocytotic channels. Submaximal pinocytosis induced by UV light was additive to pinocytosis induced by K+or Na+and stimulated in the presence of EGTA. It was not inhibited by the presence of La+++or by pretreatment with dibucaine. In these respects and with respect to optimum pH and pCa, UV induced pinocytosis resembled potassium induced pinocytosis. Accumulation of K+in the amoeba membrane after a dose of radiation may explain the similarity between pinocytosis induced by UV light and potassium salts. Ca++present during the period of irradiation inhibited the effect of UV light. Instead Ca++applied after irradiation (1–20 mM) increased channel formation. This effect was stimulated by the presence of local anesthetic drugs. It is suggested that high doses of UV light may induce channel formation by releasing Ca++from the cell membrane into the cell (UV induced pinocytosis). Ca++may be released at the moment of absorption of UV light in the membrane as well as during the period of depolarization which follows irradiation. Low doses of UV light may permit extracellular Ca++to enter the cell and stimulate channel formation (calcium induced pinocytosis). Dithiotreitol (1 mM) applied after irradiation depressed both UV and calcium induced pinocytosis so these may be the result of the same structural change which involves the formation of disulphide bonds in the me

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10215.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractA digital computer program is described for the estimation of parameters in an open two compartment system distinguishing 3 models. The mathematical function to be fitted to a given set of experimental data is given initial estimates for the parameters of the function. The program uses an iterative procedure to adjust the parameters until the sum of squares of residuals has converged to a minimum. Assuming that a given substance is introduced into compartment 1, the function can be fitted to the set of experimental data of that compartment. A set of experimental data from compartment 2 can also be included in the minimizing function. Two optional weighting functions are presented. From the constants of the two‐exponential functions the physiological parameters of the three models are determined. Experimental observations of compartment 1 only allow for calculation of physiological parameters of two of the model

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10216.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe accumulation of acetylcholine (ACh) following nerve crush was inhibited by high concentrations of colchicine (10‐1, 10‐2M) and vinblastine (10‐2‐10‐4M) in a dose‐dependent manner. The two mitotic inhibitors were effective both when applied to axons (subepineural injections) and to perikarya (injections into the lumbar intumescence). The results indicate that mitotic inhibitors, when applied locally to cholinergic motor neurons, may block the proximo‐distal transport of ACh. The possibility is discussed that this blockade is caused by an interference with a microtubule mechanism in the axons. Evidence for an increased local synthesis of ACh near the site of injection into nerves was also obtained with the highest concentrations of either s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10217.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe effects of colchicine (0.5–10‐2M) and vinblastine (10‐2‐10‐5M) upon axonal transport of choline acetyltransferase (CAT) and on nerve impulse conduction have been investigated in the rat sciatic nerve. High concentrations of colchicine (0.5 M) and vinblastine (10‐2M) blocked completely both axonal transport of CAT and impulse conduction. 10‐3M vinblastine did not affect impulse conduction until 20–22 h after injection, but this concentration of vinblastine did block CAT transport; 5 × 10‐5and 10‐4M vinblastine blocked CAT transport but not impulse conduction. 10‐2M and 10‐1M colchicine were without effect on impulse conduction, but did produce substantial, although incomplete, block of CAT transport. The results are discussed in relation to the possible involvement of microtub

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10218.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractSimilar to their actions on normally polarized, isolated sphincter of Oddi, the β‐receptor stimulators isoprenaline and terbutaline, and prostaglandin E2produced relaxation of the depolarized preparation. The relaxation was accompanied by an increase in the intracellular content of cyclic AMP. In contrast to its relaxing effect on normally polarized sphincter preparations, the C‐terminal octapeptide of cholecystokinin (C8‐CCK) contracted or had no effect on the depolarized sphincter. There was no change or a small decrease in the content of cyclic AMP in the muscle. It is suggested that the relaxing effects of β‐receptor stimulators and prostaglandin E2on isolated sphincter of Oddi, and the simultaneous increase in cyclic AMP‐content are mediated by processes independent of the electrical activity of the membrane. However, C8‐CCK mediated relaxation and increase in cyclic AMP is dependent on the membr

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10219.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe unsaturated vitamin B12‐binding capacity (UBBC) of the small molecular size vitamin B12‐binding protein (SBP) release and albumin release into the medium and the fluid pressure in the portal vein were studied with respect to their ability to reflect the state of isolated perfused rat liver. The liver was perfusedin vitrowith a synthetic medium either with or without a gas carrier. Liver damage was induced by hypoxia or noradrenalin. Variations in experimental conditions resulted in different patterns of parameters reflecting different aspects of the liver state. The fluid pressure in the portal vein reflected sensitively the circulatory state but is not always a criterion of the general condition of the isolated liver. The albumin release is a criterion of functional state but did not always reflect liver damage. However, the amount of UBBC of SBP released into the medium is a parameter reflecting sensitively the functional capacity of the liver to produce protein and also seems to indicate liver damage. The use of this parameter provides supplementary information that cannot be obtained by either of the two more conventional paramet

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10220.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe influence of parasympathetic and sympathetic nerves on the parotid gland of the rat was investigated. It was found that both divisions of the autonomic nerves evoke secretion and probably also motor effects in this gland. Secretion elicited on sympathetic stimulation was mediated both via α‐ and β‐adrenoceptors, while motor effects were mediated via α‐adrenoceptors. On stimulation of the autonomic nerves a lower duct pressure was reached in the parotid than in the submaxillary gland, and on sympathetic nerve stimulation the flow of saliva always started later from the parotid than from the submaxillary gland. These findings are discussed in the view of the different arrangement of the myoepithelial cells in the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10221.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe capacity of anin vitro‐formed protamine‐heparin complex (PHC) to store inorganic cations and biogenic amines was investigated. The PHC behaves like a two‐compartment storage system. One compartment corresponds to the terminal free carboxyl groups of the protamine moiety and has the characteristics of a cation exchanger, with the ability to bind inorganic cations and biogenic amines in a reversible and rather unselective manner. The cations and biogenic amines therefore compete for and displace each other from the common ionic binding sites. The binding sites in the other compartment, corresponding mainly to the carboxyl groups of the heparin moiety, are only unmasked at high ionic concentrations and show a specific affinity for biogenic amines. The storage of amines in this compartment of the PHC is reversible but is dependent not only on simple ionic binding but evidently also on other attractive forces, such as dipole and hydrogen bo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1976.tb10222.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY