title: Local regulation of blood flow.
abstract: H+ and K+ ions participate decisively in the local regulation of blood flow. Variation of their extracellular concentration changes the membrane potential of vascular smooth muscle cells and tension via electromechanical coupling. The effect of K+ ions can be primarily attributed to a change of K+ equilibrium potential and electrogenic pump rate, the effect of H+ ions to a change of Na+ and K+ permeability of the cell membrane. Shifts of external proton and/or cation concentrations cause changes of the binding properties of the polyanionic macromolecules in vascular connective tissue. Thus, the extracellular concentration of various cation species can very fast and drastically in the tight mesh-work of connective tissue fibres close to the membrane of vascular smooth muscle cells. Especially, the K+ adsorption with extracellular acidification as well as the cooperative K+ binding as consequence of a conformational change induced by Mg++ ions are of great importance for membrane hyperpolarization and vasodilatation.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002463:Cell Membrane Permeability; D004285:Dogs; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008564:Membrane Potentials; D009119:Muscle Contraction; D009126:Muscle Relaxation; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D011188:Potassium / Q000502:physiology; D012039:Regional Blood Flow; D012964:Sodium / Q000378:metabolism; D014664:Vasodilation
chemical_list: D012964:Sodium; D008274:Magnesium; D011188:Potassium