On the mode of action of acetylcholine in evoking adrenal medullary secretion: increased uptake of calcium during the secretory response

Douglas, W. W.; Poisner, Alan M.

doi:10.1113/jphysiol.1962.sp006940

Cited by 167 publications

(84 citation statements)

References 12 publications

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“…A possible explanaition for the increase in 5-HIAA is that these cholinergic drugs raise the level of free acetylcholine which in turn depolarizes serotonergic nerve terminals by an action analogous to the release of catecholamines in adrenal medulla (Douglas & Poisner, 1962) and of noradrenaline from sympathetic neurones in heart (Richardson & Woods, 1959;Haeusler, Thoenen, Haefely & Hurlimann, 1968) and spleen (Kopin, 1966). The data in Table 6 are in accord with this speculation, since the drugs which raised 5-HIAA might be expected also to increase the concentration of acetylcholine in brain.…”

Section: Discussionmentioning

confidence: 99%

Turnover rate of brain 5‐hydroxytryptamine increased by D‐amphetamine

Reid

Derr

1970

British J Pharmacology

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Summary1. Administration of two doses of amphetamine HCl (5 mg/kg intraperitoneally) 45 min apart raised body temperature of rats by an average of 3.40 C and increased the turnover rate of brain 5-hydroxytryptamine (5-HT) by almost one-half. 2. Both effects were blocked by exposure to 40 C or by pretreatment with the B-blocker Ko 592 (1-(2-methylphenoxy)-3-isopropylamino-2-propanol), but not by the administration of the ganglionic blocker chlorisondamine combined with atropine. 3. Since it has previously been shown that hyperthermia per se increases the turnover rate of brain 5-HT, and that amphetamine does not directly affect the uptake and release of 5-HT in brain slices, it is concluded that the amphetamineinduced increase in 5-HT turnover may be secondary to the rise in temperature produced by the drug.

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Section: Discussionmentioning

confidence: 99%

Turnover rate of brain 5‐hydroxytryptamine increased by D‐amphetamine

Reid

Derr

1970

British J Pharmacology

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“…In this process Ca z+ ions were believed to play an important role since Ca 2+ ions are required in the extracellular fluid to stimulate a secretory cell successfully [25,27,35,37,52]. Later from flux measurements in different systems it was concluded that an increase of intracellular Ca 2 + may be necessary for the transformation of the stimulus into release of secretory products [13,23,24,26,36,48,49]. Recently the rise of intracellular concentrations of Ca 2 +, detected by injection of aeqorin into nerve terminals, was found to parallel stimulation and transmitter release [45].…”

Section: Discussionmentioning

confidence: 99%

Fusion of secretory vesicles isolated from rat liver

Gratzl

Dahl

1978

J. Membrain Biol.

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Summary. Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca 2 +. Vesicle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca 2 +-concentrations and is half maximal around 10 -6 M. Other divalent cations (Ba 2+, Sr 2+, and Mg 2+) were ineffective. Mg 2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesicles in vitro is Ca z+ specific and exhibits properties similar to the exocytotic process of various secretory cells.Various substances affecting secretion in vivo (microtubular inhibitors, local anesthetics, ionophores) were tested for their effect on membrane fusion in our system.The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca 2+, and in its Cag+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences.Membrane fusion is an essential event in a variety of cell functions such as cell fusion, uptake of extracellular material (endocytosis) and release of cell products (exocytosis). Elucidation of the molecular mechanism of membrane fusion has been hampered by the lack of suitable systems for studying this process. Studies with intact cells have not yielded data which lead to ready interpretation concerning subcellular processes. On the other hand, studies with artificial membranes may be only tangentially related to the fusion of biological membranes.Recently our group investigated the fusion of isolated biological membranes [16,17,31,33,69,74]. We observed that Ca 2+ specifically induces the fusion of isolated secretory vesicles in a buffered sucrose medium.Intervesicular fusion of secretory vesicles, as well as the interaction between the cell membrane and the vesicle membrane, was observed in a variety of secretory cells [2,3,6,18,29,39,53,65]. Douglas [20] showed that in "compound exocytosis" by mast cells an external stimulus initiates fusion between secretory vesicle membranes and the

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“…The fact that extracellular Ca2+ is essential for release of CA by ACh from the adrenal medulla has been well established (1,18,19). In this case the entry of Ca2+ across the membrane would be the first step of a chain of events leading to release of CA.…”

Section: Discussionmentioning

confidence: 99%

“…In this case the entry of Ca2+ across the membrane would be the first step of a chain of events leading to release of CA. Indeed, Ca2+ uptake into chromaffin cells is distinctly increased during stimulation by ACh (18), and this increase is thought to be due to changes in permeability of the cell membrane to common species of ions of chromafpin cells accompanied by depolarization. Deprivation of Ca2+ from the environmental medium reduces the increase in Ca2+ uptake resulting in reduction of CA release from the adrenal medulla (1).…”

Section: Discussionmentioning

confidence: 99%