Comparison of Isotonic Activation of Cell Volume Regulation in Rat Peritoneal Mesothelial Cells and in Kidney Outer Medullary Collecting Duct Principal Cells

Abstract

In disease states, mesothelial cells are exposed to variable osmotic conditions, with high osmotic stress exerted by peritoneal dialysis (PD) fluids. They contain unphysiologically high concentrations of glucose and result in major peritoneal membrane transformation and PD function loss. The effects of isotonic entry of urea and myo-inositol in hypertonic (380 mOsm/kg) medium on the cell volume of primary cultures of rat peritoneal mesothelial cells and rat kidney outer medullary collecting duct (OMCD) principal cells were studied. In hypertonic medium, rat peritoneal mesothelial cells activated a different mechanism of cell volume regulation in the presence of isotonic urea (100 mM) in comparison to rat kidney OMCD principal cells. In kidney OMCD cells inflow of urea into the shrunken cell results in restoration of cell volume. In the shrunken peritoneal mesothelial cells, isotonic urea inflow caused a small volume increase and activated regulatory volume decrease (RVD). Isotonic myo-inositol activated RVD in hypertonic medium in both cell types. Isotonic application of both osmolytes caused a sharp increase of intracellular calcium both in peritoneal mesothelial cells and in kidney OMCD principal cells. In conclusion, peritoneal mesothelial cells exhibit RVD mechanisms when challenged with myo-inositol and urea under hyperosmolar isotonic switch from mannitol through involvement of calcium-dependent control. Myo-inositol effects were identical with the ones in OMCD principal cells whereas urea effects in OMCD principal cells led to no RVD induction.

Role of Peritoneal Mesothelial Cells in the Progression of Peritoneal Metastases

“…The peritoneum is a semi-permeable membrane that allows the passive transport of fluids and solutes through intercellular junctions, hydrostatic and osmotic pressure gradients via the stomata, and active transport via the formation of (micro)pinocytotic vesicles [ 9 , 10 , 11 ]. The ion channels at the PMC membrane regulate the volume of PMCs according to a change in osmotic pressure [ 8 , 12 , 13 , 14 , 15 , 16 ].…”

The Integral Role of Chloride & With-No-Lysine Kinases in Cell Volume Regulation & Hypertension

“…In cases of increased potassium consumption, the kidneys play a crucial role in maintaining extracellular volume and potassium homeostasis to achieve a delicate balance between the conservation of extracellular volume and the excretion of excess potassium. According to the literature mentioned in the paragraph above as well as newer data presented by Baturina GS et al 9 kidney epithelial cells exhibit the ability of cell volume regulation from the proximal tubule to the distal tubule and collecting duct, although the osmotic challenge is not equal for each individual segment of the nephron. This variability implies that different nephron epithelial cells may prioritize tasks differently.…”

Molecular Mechanisms of Peritoneal Membrane Pathophysiology

“…Baturina and coworkers describe the mesothelial cell response to osmotic stress as compared to kidney outer medullary collecting duct cells [ 6 ]. Each inflow of PD fluid exposes mesothelial cells to far supraphysiological concentrations of glucose required for fluid removal from the patient, and the cellular response to the high osmotic stress is largely unknown.…”