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Ultrastructural localization of the membrane-bound Mg-adenosine triphosphatase activity in rat meninges
Abstract:
The distribution of the membrane-bound magnesium ions-dependent adenosine triphosphatase (Mg-ATPase) activity has been studied ultracytochemically in rat meninges by the method of Wachstein and Meisel (1957). A device specially constructed to avoid preparation artefacts has been used to obtain sections from the parietal region of the head. The meninges display an intense though irregularly distributed ATPase activity marked by depositions of electron-dense reaction product (RP) which is almost absent in the outer and middle dural layers. In the borderline zone between dura mater and the arachnoid the RP deposits are found at the outer surface of the inner dural cells and at the contact sites between these cells and the dural neurothelium. The intercellular cleft(s) between the neurothelium and the outer arachnoidal layer, occupied by an "electron-dense band", remains free of RP. The strongest accumulations of reactions granules are observed on the surface of the leptomeningeal cells of the arachnoidal space. In the contact region between the inner arachnoidal and the outer pial layers the distribution of the RP is similar to the one observed in the interface zone dura mater/arachnoid, while the pial cells themselves are definitely reaction-positive. In all meningeal vessels RP is found at the lumenal and abluminal aspects of the endothelium as well as at the cell membranes of the perivascular cells. These results emphasize the importance of the dural neurothelium for the functions of the blood-cerebrospinal fluid (CSF)-barrier between the dural blood vessels and the CSF.
Insights
Magnesium ions-dependent adenosine triphosphatase (Mg-ATPase) activity is unevenly distributed in rat meninges. This enzyme is crucial for the blood-cerebrospinal fluid barrier function.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- The meninges form a critical interface between the central nervous system and the periphery.
- Understanding the enzymatic activity within the meninges is key to comprehending the blood-cerebrospinal fluid (CSF) barrier.
- Magnesium ions-dependent adenosine triphosphatase (Mg-ATPase) is a vital enzyme involved in cellular transport and energy metabolism.
Purpose of the Study:
- To ultracytochemically map the distribution of Mg-ATPase activity in rat meninges.
- To investigate the role of Mg-ATPase in the structural components of the meninges.
- To elucidate the contribution of meningeal Mg-ATPase to the blood-CSF barrier function.
Main Methods:
- Ultracytochemical localization of Mg-ATPase activity using the Wachstein and Meisel method (1957).
- Preparation of meningeal sections using a specialized device to minimize artefacts.
- Electron microscopy to visualize reaction product (RP) deposition.
Main Results:
- Mg-ATPase activity was intensely, though irregularly, distributed across the meninges, with notable exceptions in outer and middle dural layers.
- High concentrations of reaction product were observed on leptomeningeal cells and at specific interfaces between dural and arachnoid layers.
- Enzymatic activity was present on the luminal and abluminal sides of meningeal vessel endothelium and perivascular cells.
Conclusions:
- The dural neurothelium plays a significant role in the blood-CSF barrier.
- Mg-ATPase activity is localized in key cellular components of the meninges, suggesting its involvement in barrier maintenance.
- Ultracytochemical findings highlight the functional importance of specific meningeal layers and cells in regulating transport between blood and CSF.