Methyl isobutyl amiloride: A new probe to assess the number of NaH antiporters

Talor, Zvi; Ng, Silvania C.; Cragoe, Edward J.; Arruda, José A.L.

doi:10.1016/0024-3205(89)90102-1

Cited by 23 publications

(9 citation statements)

References 11 publications

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“…Consequently, the effect of amiloride and methyl-isobutyl-amiloride, Na+/H § antiport inhibitors (Moolenaar et al, 1983) was studied. Preincubation of chromatiin cells for 3 min with increasing concentrations of amiloride or its analogue, methyl-isobutyl-amiloride (Talor et al, 1989), did not affect cortical scinderin redistribution but inhibited in a dosedependent manner the subsequent nicotine-or PMA-induced scinderin redistribution (Fig. 12, A and B, open symbols).…”

Section: Inhibitory Effects Of Amiloride and Methyl-isobutyl Amiloridmentioning

confidence: 93%

Ca2+ and pH determine the interaction of chromaffin cell scinderin with phosphatidylserine and phosphatidylinositol 4,5,-biphosphate and its cellular distribution during nicotinic-receptor stimulation and protein kinase C activation.

Castillo

Vitale

Trifaró

1992

The Journal of Cell Biology

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Abstract. Nicotinic stimulation and high K § -ization of chromaffin cells cause disassembly of cortical filamentous actin networks and redistribution of scinderin, a Ca2+-dependent actin filament-severing protein. These events which are Ca2+-dependent precede exocytosis. Activation of scinderin by Ca ~ § may cause disassembly of actin filaments leaving cortical areas of low cytoplasmic viscosity which are the sites of exocytosis (Vitale, M. L., A. Rodriguez Del Castillo, L. Tchakarov, and J.-M. Trifar6. 1991. J. Cell. Biol. 113:1057-1067. It has been suggested that protein kinase C (PKC) regulates secretion. Therefore, the possibility that PKC activation might modulate scinderin redistribution was investigated. Here we report that PMA, a PKC activator, caused scinderin redistribution, although with a slower onset than that induced by nicotine. PMA effects were independent of either extra or intracellular Ca 2 § as indicated by measurements of Ca 2 § transients, and they were likely to be mediated through direct activation of PKC because inhibitors of the enzyme completely blocked the response to PMA. Scinderin was not phosphorylated by the kinase and further experiments using the Na+/H § antiport inhibitors and intracellular pH determinations, demonstrated that PKC-mediated scinderin redistribution was a consequence of an increase in intracellular pH. Moreover, it was shown that scinderin binds to phosphatidylserine and phosphatidylinositol 4,5-biphosphate liposomes in a Ca2 § manner, an effect which was modulated by the pH. The results suggest that under resting conditions, cortical scinderin is bound to plasma membrane phospholipids. The results also show that during nicotinic receptor stimulation both a rise in intracellular Ca 2 § and pH are observed. The rise in intracellular pH might be the result of the translocation and activation of PKC produced by Ca ~ § entry. This also would explain why scinderin redistribution induced by nicotine is partially (26-40%) inhibited by inhibitors of either PKC or the Na+/H § antiport. In view of these findings, a model which can explain how scinderin redistribution and activity may be regulated by pH and Ca 2 § in resting and stimulated conditions is proposed.

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Section: Inhibitory Effects Of Amiloride and Methyl-isobutyl Amiloridmentioning

confidence: 93%

Ca2+ and pH determine the interaction of chromaffin cell scinderin with phosphatidylserine and phosphatidylinositol 4,5,-biphosphate and its cellular distribution during nicotinic-receptor stimulation and protein kinase C activation.

Castillo

Vitale

Trifaró

1992

The Journal of Cell Biology

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“…The 3.8-kb NHE1 promoter fragment contains all of the upstream elements that are important for expression in mammalian cells (50). This sensitive system was necessary to detect changes in the level of NHE1 transcription because the Na ϩ /H ϩ exchanger promoter is a relatively weak promoter (14) and only a very low level of NHE1 protein is expressed in cells (45). When we examined the relative levels of transcription in whole mouse embryos using GFP as a reporter, we found a time-and tissue-dependent regulation of NHE1 transcription.…”

Section: Discussionmentioning

confidence: 99%

Developmental regulation of Na⁺/H⁺exchanger expression in fetal and neonatal mice

Rieder

Fliegel

2002

American Journal of Physiology-Heart and Circulatory Physiology

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We examined the hypothesis that Na+/H+ exchanger expression is regulated during fetal and neonatal development and differentiation. To examine transcriptional regulation of the NHE1 isoform of the Na+/H+ exchanger, transgenic mice were created that contained the mouse NHE1 promoter driving expression of green fluorescent protein. The level of NHE1 transcription varied between tissues and with the stage of embryonic development. The highest expression was in the heart and liver of 12- to 15-day-old mice, and this declined with age. To examine Na+/H+exchanger protein levels, we immunoblotted mouse tissues from 18-day-old embryos, neonates, and adults. Protein levels increased after embryonic day 18 and peaked at 14 days of age in the heart, lung, liver, kidney, and brain. The greatest rise in NHE1 protein expression occurred in the heart, whereas the smallest increase was in the brain. The results suggest that Na+/H+ exchanger transcription and protein levels are controlled in a tissue-specific and time-dependent manner during development.

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“…pH i recovered when the Na ϩ -free solution was replaced with Na ϩ -containing Hanks' buffer solution. This Na ϩ -dependent recovery was inhibited by the Na ϩ -H ϩ exchange blocker 5-(N-methyl-N-isobutyl) amiloride (MIA) (10 Ϫ5 mol/L) 42,45 and was operationally defined as Na ϩ -H ϩ exchange activity. 43,44 To quantify the rate of pH i recovery, a straight line was fitted to the initial 60 seconds after the onset of recovery, and the respective slopes were compared.…”

Section: Cell Culturementioning

confidence: 99%

Activation of the Na ⁺ -H ⁺ Exchanger Modulates Angiotensin II–Stimulated Na ⁺ -Dependent Mg ²⁺ Transport in Vascular Smooth Muscle Cells in Genetic Hypertension

Touyz

Schiffrin

1999

Hypertension

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Methyl isobutyl amiloride: A new probe to assess the number of NaH antiporters

Cited by 23 publications

References 11 publications

Ca2+ and pH determine the interaction of chromaffin cell scinderin with phosphatidylserine and phosphatidylinositol 4,5,-biphosphate and its cellular distribution during nicotinic-receptor stimulation and protein kinase C activation.

Ca2+ and pH determine the interaction of chromaffin cell scinderin with phosphatidylserine and phosphatidylinositol 4,5,-biphosphate and its cellular distribution during nicotinic-receptor stimulation and protein kinase C activation.

Developmental regulation of Na⁺/H⁺exchanger expression in fetal and neonatal mice

Activation of the Na ⁺ -H ⁺ Exchanger Modulates Angiotensin II–Stimulated Na ⁺ -Dependent Mg ²⁺ Transport in Vascular Smooth Muscle Cells in Genetic Hypertension

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Methyl isobutyl amiloride: A new probe to assess the number of NaH antiporters

Cited by 23 publications

References 11 publications

Ca2+ and pH determine the interaction of chromaffin cell scinderin with phosphatidylserine and phosphatidylinositol 4,5,-biphosphate and its cellular distribution during nicotinic-receptor stimulation and protein kinase C activation.

Ca2+ and pH determine the interaction of chromaffin cell scinderin with phosphatidylserine and phosphatidylinositol 4,5,-biphosphate and its cellular distribution during nicotinic-receptor stimulation and protein kinase C activation.

Developmental regulation of Na+/H+exchanger expression in fetal and neonatal mice

Activation of the Na + -H + Exchanger Modulates Angiotensin II–Stimulated Na + -Dependent Mg 2+ Transport in Vascular Smooth Muscle Cells in Genetic Hypertension

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Developmental regulation of Na⁺/H⁺exchanger expression in fetal and neonatal mice

Activation of the Na ⁺ -H ⁺ Exchanger Modulates Angiotensin II–Stimulated Na ⁺ -Dependent Mg ²⁺ Transport in Vascular Smooth Muscle Cells in Genetic Hypertension