| 1. |
- Ekström, J., et al.
(author)
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Receptors involved in the nervous system regulation of polyamine metabolism in rat salivary glands
- 1989
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 135:3, s. 61-255
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Journal article (peer-reviewed)abstract
- Polyamines are important for protein synthesis and tissue growth. In rat salivary glands, the activity of ornithine decarboxylase (ODC), the enzyme catalysing the formation of putrescine, and the content of putrescine, spermidine, spermine and N1-acetylspermidine were assayed after parasympathetic or sympathetic nerve stimulation in the presence of various autonomic receptor blockers. Increases in ODC activity occurred on activation of non-adrenergic and non-cholinergic receptors in response to parasympathetic nerve stimulation and on activation of alpha(alpha 1)- as well as of beta(beta 1)-adrenoceptors in response to sympathetic nerve stimulation. Moreover, in parotid glands, a beta(beta 1)-adrenoceptor-mediated inverse pathway for putrescine formation seemed to exist: from spermidine via N1-acetylspermidine.
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| 2. |
- Ekström, J., et al.
(author)
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Spermidine/spermine-N1-acetyltransferase activity in isoprenaline-stimulated rat salivary glands
- 1989
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 135:3, s. 54-249
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Journal article (peer-reviewed)abstract
- In parotid, sublingual and submaxillary glands stimulated by continuous intravenous infusion of isoprenaline at various doses for 3 h, the concentrations of the polyamines putrescine, spermidine, spermine and N1-acetylspermidine as well as the activities of ornithine decarboxylase and spermidine/spermine-N1-acetyltransferase were determined. Ornithine decarboxylase is the enzyme that catalyses the formation of putrescine from ornithine. The most striking effect was observed in parotid glands. Here, the beta-adrenergic agonist increased the activity of spermidine/spermine-N1-acetyltransferase markedly, but only slightly (if at all) that of ornithine decarboxylase. It also increased the concentrations of N1-acetylspermidine and putrescine markedly. The result obtained in this gland indicates interconversion of higher polyamines to putrescine.
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| 3. |
- Jansson, M, et al.
(author)
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Effects of luminal stimuli on polyamine metabolism in the small intestine of the rat : the role of enteric nerves
- 1993
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 149:4, s. 90-483
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Journal article (peer-reviewed)abstract
- The aim of this study was to investigate to what extent polyamine metabolism in the small intestine of the rat is controlled by the enteric nervous system. Polyamine metabolism was followed by measuring the activity of ornithine decarboxylase (ODC) and in some instances also the content of polyamines (putrescine, spermidine and spermine). ODC activity in the intestine was increased when intraluminal pressure was increased and 3 h after placing cholera toxin in the intestinal lumen. Cholera toxin also increased the tissue putrescine content. Atropine or hexamethonium given i.v. did not influence the evoked changes of ODC activity. The pressure induced changes were not decreased by placing lidocaine on the serosal surface. On the other hand, the ODC activity of control segments were decreased by hexamethonium or atropine. The presence of glucose in the intestinal perfusate did not augment tissue ODC activity, neither did the heat stable enterotoxin from Escherichia coli (STa). It is concluded that the effect on polyamine metabolism evoked by luminal pressure or cholera toxin seems not to be mediated via nerves, while nerves seem to influence ODC activity during control conditions. The experiments with enterotoxins suggest that cAMP is the intracellular second messenger controlling intestinal ODC activity.
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| 4. |
- Nilsson, B O, et al.
(author)
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Differential actions of exogenous and intracellular spermine on contractile activity in smooth muscle of rat portal vein
- 1995
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 154:3, s. 65-355
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Journal article (peer-reviewed)abstract
- Effects of the naturally occurring polyamine spermine on electrical and contractile properties of the rat portal vein were studied. 1 mM spermine nearly abolished spike activity and spontaneous contractions and decreased the intracellular Ca2+ concentration ([Ca2+]i). The phasic force responses to 0.1 and 1 microM phenylephrine were partially inhibited, but not the sustain plateau contraction caused by 5 microM phenylephrine. The Ca(2+)-force relation in high-K+ (128 mM)-depolarized veins was shifted to the right, EC50 for Ca2+ increasing from 0.50 +/- 0.03 mM (control, n = 8) to 0.65 +/- 0.06 and to 0.94 +/- 0.03 at 1 (n = 4) and 10 (n = 3) mM spermine, respectively. However, at a Ca2+ concentration of 2.5 mM, giving maximal force, there was no effect of spermine (1 mM) on either force or [Ca2+]i. Whereas extracellular spermine thus reduced contractile activity at moderate levels of stimulation, increased intracellular concentration of spermine potentiated the force response to Ca2+. Intracellular loading of spermine by reversible permeabilization increased its concentration by 2-3 times. The spontaneous activity and response to phenylephrine were unchanged. However, the Ca(2+)-force relation of depolarized veins was shifted to the left, EC50 decreasing from 0.51 +/- 0.04 mM in controls (n = 7) to 0.36 +/- 0.02 mM in the loaded veins (n = 9). Spermine increased Ca(2+)-activated force in portal veins permeabilized with beta-escin. The degree of potentiation was consistent with observed effects in spermine-loaded intact veins. The results suggest that spermine at physiological intracellular concentration may contribute to the determination of Ca2+ sensitivity in vascular smooth muscle cells.
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| 5. |
- Nilsson, B O, et al.
(author)
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Effects of stimulation of the parasympathetic and sympathetic innervations in bursts on the syntheses of polyamines, DNA and protein in salivary glands of the rat;non-adrenergic, non-cholinergic responses : non-adrenergic, non-cholinergic responses
- 1991
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 143:2, s. 8-161
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Journal article (peer-reviewed)abstract
- The increase in the activity of ornithine decarboxylase, the key enzyme in the formation of polyamines, in the sublingual glands of the chloralose-anaesthetized rat in response to stimulation of the parasympathetic innervation was enhanced by employing an intermittent pattern of nerve stimulation. 20 Hz in bursts delivered for 1 second every 10th second over a period of 3 hours increased the activity 1000-fold, whereas a frequency of 2 Hz delivered continuously, and thus giving rise to the same total number of impulses as the burst stimulation, increased the enzyme activity only 50-fold. Already 2 Hz in bursts caused the ornithine decarboxylase activity to increase. A parasympathetic non-adrenergic, non-cholinergic regulation of ornithine decarboxylase activity was shown in response to the two modes of stimulation. The increase to 2 and 20 Hz in bursts was 2- and 80-fold, respectively, whereas it was 29-fold to 2 Hz continuously. Increases in the concentration of the polyamine putrescine in response to burst stimulation of the parasympathetic nerve were found both in the absence and in the presence of atropine. The ornithine decarboxylase activity of the submaxillary gland was not affected by the parasympathetic stimulation. Stimulation of the sympathetic innervation was more effective in both types of glands, as to increases in the ornithine decarboxylase activity, when employing the continuous mode. In cultured tissue of the sublingual glands which, in vivo, had been subjected to parasympathetic stimulation in bursts (20 Hz), the syntheses of DNA and protein were increased as judged by the incorporation of radio-labelled thymidine and leucine; in the presence of atropine the stimulation resulted only in increased synthesis of protein.
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| 6. |
- Nilsson, B O
(author)
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Polyamines and long-term disuse of rat parotid glands
- 1990
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 140:1, s. 9-105
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Journal article (peer-reviewed)abstract
- A decrease in nerve reflex activation for 7-14 days, induced by a liquid diet, caused the rat parotid gland to lose weight, involving reduction in both cell size and number. In the atrophied glands, the activity of ornithine decarboxylase, the key enzyme in polyamine formation, and the levels of the polyamines putrescine, spermidine and spermine were found to be lowered. The present results are compatible with a role for polyamines in cellular growth.
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| 7. |
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| 8. |
- Nilsson, B O
(author)
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Substance P and vasoactive intestinal peptide influence polyamine metabolism in salivary glands of the rat
- 1989
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 136:3, s. 33-427
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Journal article (peer-reviewed)abstract
- In parotid, sublingual and submaxillary glands stimulated by continuous intravenous infusion of the neuropeptides substance P or vasoactive intestinal peptide at various doses for 3 h, the concentrations of the polyamines putrescine, spermidine, spermine and N1-acetylspermidine as well as the activity of ornithine decarboxylase were determined. This enzyme catalyses the synthesis of putrescine and is the key enzyme in polyamine formation. Vasoactive intestinal peptide induced the most marked effects, and the most conspicuous findings were made in the sublingual glands, where the ornithine decarboxylase activity was found to have increased more than 100-fold, accompanied by an increased level of putrescine in those glands which were removed immediately after the end of the infusion. When, instead, the glands were removed 5 h after the end of the infusion there was no longer any increase in the activity of ornithine decarboxylase or in putrescine concentration, but now spermidine and spermine were found to be increased. Interestingly, the parasympathetic non-adrenergic, non-cholinergic regulation of polyamine metabolism in the major salivary glands of the rat is most predominant in the sublingual glands.
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