Regulation of Mg²⁺ uptake in isolated rat myocytes and hepatocytes by protein kinase C

Abstract

A large Mg:* cell uptake against concentration gradients is stimulated in collagenase-disper~ed ra: myocytes by carbachol and in hepato~t~ by carbachol or vasoprcssin. The signalling pathway(s) responsible for this stimulation o1" Mg ~-+ uptake was inv.+stigated by using various activators or inhibitors of protein kinase C (PKC) and by correlatin/~ Mg :+ uptake with cell PKC activity and cAMP content. In both cell preparations, the dir~.,ct stimulation of PKC by diaeylglycerol analogs or phorbol esters reproduce the same pattern of MS -+" uptake as that induced by carbachol or vasopressin. These data indicate that the activation of PKC is responsible for a stimulation of Mg:" uptake by myocytes or hepatocytes, whereas increase in cAMP in these cells stimulates Mg a' release.

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

“…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.…”

“…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.…”

Characterization of the Na+-dependent Mg2+transport in sheep ruminal epithelial cells

“…The effect was contributed to multiple intracellular signaling pathways, including cAMP-mediated PKA activation as well as stimulation of phospholipase C and of the protein kinase C (PKC) pathway. In rat heart myocytes and liver cells, intracellular cAMP formation stimulates Mg 2ϩ efflux, and Mg 2ϩ accumulation was related to changes in PKC activity (29). Further experiments at the whole epithelium level are necessary to confirm the stimulating effect of PGE 2 …”

Angiotensin II Type I Receptor Modulates Intracellular Free Mg2+ in Renally Derived Cells via Na+-dependent Ca2+-independent Mechanisms

“…The Na ϩ / Mg 2ϩ exchanger was first demonstrated in the squid giant axon where Na ϩ entry is coupled to Mg 2ϩ moving out of the cell (14). Na ϩ -dependent Mg 2ϩ transport is inhibited by amiloride, quinidine, imipramine, and manganese, and it may be regulated by cAMP, protein kinase C, and the Na ϩ /H ϩ antiporter (15)(16)(17)(18)(19). Although the transporter has been functionally demonstrated, it has not yet been cloned or characterized.…”