Mg2+ Homeostasis in cardiac ventricular myocytes

Romani, Andrea; Marfella, C.; Scarpa, Antonio

doi:10.1007/978-3-0348-9057-1_16

Cited by 12 publications

(21 citation statements)

References 24 publications

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“…In response to activation of specific cell signaling, it has been shown that massive amounts of total Mg 2ϩ can be translocated within minutes in or out of hepatocytes (7,8,10). This indicated a very powerful and rapid transport machinery of Mg 2ϩ transport within the plasma membrane.…”

Section: Properties Of Plasma Membrane Mgmentioning

confidence: 99%

“…Yet, the Mg 2ϩ transporter(s) has not been isolated, and even the basic kinetic properties of Mg 2ϩ cellular transport remain confusing and contradictory. For example, the dependence of Mg 2ϩ release on extracellular Na ϩ has been established in invertebrate and mammalian cells (11-16) but Na ϩ -independent pathways have also been reported (1,8,9,17,18). Equally contradictory are the findings of variable Na ϩ / Mg 2ϩ stoichiometries (1,19), the role of trans-membrane potential, and the partial and variable effectiveness of inhibitors such as amiloride (for review see Refs.…”

mentioning

confidence: 99%

“…Recent evidence in the literature demonstrates that the perfused liver or isolated hepatocytes can accumulate or release very large amounts of Mg 2ϩ upon specific metabolic stimulation (7,8). Recently, this laboratory was able to successfully obtain sealed liver plasma membranes (LPM) 1 to study Mg 2ϩ transport across the hepatocyte cell membrane (21).…”

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confidence: 99%

“…Using sealed plasma membranes, we recently found that either extravesicular Na ϩ or Ca 2ϩ could mobilize intravesicular Mg 2ϩ (21). A major difference in liver plasma membrane vesicles is that they release intravesicular Mg 2ϩ in the presence of extravesicular Na ϩ or Ca 2ϩ alone, without the need of metabolic stimulation (21) necessary in intact hepatocytes (7,8). Under these conditions, cellular Mg 2ϩ transport appears "uncoupled" and maximally operating in the absence of stimulatory cellular signals.…”

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confidence: 99%

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Differential Localization and Operation of Distinct Mg2+ Transporters in Apical and Basolateral Sides of Rat Liver Plasma Membrane

Cefaratti

Romani

Scarpa³

2000

Journal of Biological Chemistry

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Upon activation of specific cell signaling, hepatocytes rapidly accumulate or release an amount of Mg 2؉ equivalent to 10% of their total Mg 2؉ content. Although it is widely accepted that Mg 2؉ efflux is Na ؉ -dependent, little is known about transporter identity and the overall regulation. Even less is known about the mechanism of cellular Mg 2؉ uptake. Using sealed and right-sided rat liver plasma membrane vesicles representing either the basolateral (bLPM) or apical (aLPM) domain, it was possible to dissect three different Mg 2؉ transport mechanisms based upon specific inhibition, localization within the plasma membrane, and directionality. The bLPM possesses only one Mg 2؉ transporter, which is strictly Na ؉ -dependent, bi-directional, and not inhibited by amiloride. The aLPM possesses two separate Mg 2؉ transporters. One, similar to that in the bLPM because it strictly depends on Na ؉ transport, and it can be differentiated from that of the bLPM because it is unidirectional and fully inhibited by amiloride. The second is a novel Ca 2؉ /Mg 2؉ exchanger that is unidirectional and inhibited by amiloride and imipramine. Hence, the bLPM transporter may be responsible for the exchange of Mg 2؉ between hepatocytes and plasma, and vice versa, shown in livers upon specific metabolic stimulation, whereas the aLPM transporters can only extrude Mg 2؉ into the biliary tract. The dissection of these three distinct pathways and, therefore, the opportunity to study each individually will greatly facilitate further characterization of these transporters and a better understanding of Mg 2؉ homeostasis.Magnesium, the second most abundant cation within mammalian cells, is necessary for a variety of metabolic and cellular functions (1-5). Under resting conditions, cellular-free Mg 2ϩ concentration is held at 0.5-0.8 mM, well below its predicted electrochemical equilibrium, and approximately 5 mM Mg 2ϩ is complexed with ATP and other metabolites (1, 5). In several tissues such as heart and liver, specific hormonal or metabolic stimulation causes, within a few minutes, a massive mobilization of cellular Mg 2ϩ (6 -9). Although cytosolic-free Mg 2ϩ undergoes minimal changes, several intracellular signals leading to a cAMP increase induce a loss of 5-10% of total cellular Mg 2ϩ (6 -9). Conversely, signals activating protein kinase C result in an accumulation of Mg 2ϩ and a consequent increase of total cellular Mg 2ϩ by 5-10% (10). These findings underscore the operation of a very powerful Mg 2ϩ transport machinery within the plasma membranes of mammalian cells. Yet, the Mg 2ϩ transporter(s) has not been isolated, and even the basic kinetic properties of Mg 2ϩ cellular transport remain confusing and contradictory. For example, the dependence of Mg 2ϩ release on extracellular Na ϩ has been established in invertebrate and mammalian cells (11-16) but Na ϩ -independent pathways have also been reported (1,8,9,17,18). Equally contradictory are the findings of variable Na ϩ / Mg 2ϩ stoichiometries (1,19), the role of trans-membrane potenti...

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Section: Properties Of Plasma Membrane Mgmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Differential Localization and Operation of Distinct Mg2+ Transporters in Apical and Basolateral Sides of Rat Liver Plasma Membrane

Cefaratti

Romani

Scarpa³

2000

Journal of Biological Chemistry

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“…For example, the concentrations of catecholamines are increased during exercise. High adrenaline concentrations are associated with a decrease of the influx of Mg into cells which results in a net efflux of Mg from the intracellular compartment (Durlach, 1980;Romani et al, 1993). Moreover, increased serum free fatty acids concentrations as a consequence of increased lypolysis which occurs during exercise induce a decrease in the Mg concentrations (Flink et al, 1979).…”

Section: Discussionmentioning

confidence: 99%

Effects of sweat loss induced by treadmill exercise on magnesium and calcium homeostasis in Franches- Montagnes horses

Weiß¹,

Weishaupt²,

Forrer³

et al. 2002

PHK

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SummaryThe physological consequences of magnesium and calcium loss via sweat during a prolonged exercise test was investigated in eleven stallions. The test on a high-speed treadmill inclined at 3% consisted of 6 trot-intervals of 20 min each at 3.0 m/s. Blood samples were collected 1 hour before the exercise test, after each trot-interval and after 1 and 2 hours of recovery. The body weight loss ranged between 19 and 25 kg with a mean reduction of the body mass of 3.71% ± 0.45. Mean total magnesium concentration decreased continuously during the exercise and the first hour of the recovery period. Mean erythrocyte magnesium concentration decreased during the last two trot intervals and was significantly lower during the second hour of recovery. The mean total calcium concentration decreased during the exercise test and increased during the recovery period. Mean parathyroid hormone serum concentrations at the end of the test were significantly greater. Serum 1,25-dihydroxyvitamin D concentrations did not change with time. According to the results of the present study, additional magnesium and calcium supply are superfluous in the case of a single prolonged exercise. However, high dietary supply may be beneficial in hard working and heavily sweating horses to prevent the occurence of critically low ionised magnesium and calcium values. Keywords:horse, magnesium, calcium, treadmill, sweat, nutrition

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