メサンギウム細胞の機能とtransmembrane signalling

抄録

Mesangial cells, which were discovered by Zimmermann, occupy the axialregion of renal glomerular network, and have some functions such as modulation of glomerular filtration rate (GFR), macromolecule uptake and production of several substances. Vasoactive agents, angiotensin II, vasopressin, platelet-derived growth factor (PDGF) and platelet-activating factor (PAF), stimulate mesangial cell contraction, which decreases GFR through the reduction of ultrafiltration coefficient of single nephron GFR. These vasoactive agents activate phosphoinositide (PI) cycle, and produce diacylglycerol and inositol-phosphates in mesangial cells. Vasorelaxant agents, dopamine and atrial natriuretic peptide (A NP), do not activate PI cycle. Dopamine produces cAMP and ANP synthesizes cGMP. These vasorelaxant agents suppress mesangial cell contraction and decrease in GFR induced by vasoactive agents.
Mesangial cell proliferation is a common feature of various forms of glomerulonephritis. It is very important to clarify growth factors for mesangial cells and their mechanism of mesangial cell proliferation. These vasoactive agents stimulate mesangial cell proliferation, on the other hand, vasorelaxant agents inhibit it. Vasoactive agents may stimulate not only mesangial cell contraction but also mesangial cell proliferation probably through activation of PI cycle, but vasorelaxant agents may suppress activation of PI cycle enhanced by vasoactive agents through cAMP or cGMP.