Blood Vessel Hyperpolarization

For many diseases, such as cardiovascular diseases and diabetes, functions of blood vessel are often reduced resulting in reduction in blood supply. Na/K pumps in the smooth muscles play a significant role in dilation of the blood vessels. Activation of the Na/K pumps hyperpolarizes the membrane potential, reducing Ca influx, and consequently relaxing the

smooth muscle cells and dilating the vessels. Left figure shows the membrane potential changes (measured by a microelectrode) of a smooth muscle cell from rat mesenteric peripheral blood vessel when the vessel is non-invasively exposed to a synchronization modulation electric field. The upper left represents profile of the membrane potential change in response the field application. The potential changes during the synchronization and modulation stages are redrawn in the lower left panel. Average of the oscillating membrane potential vs. time is shown in the upper right panel which exhibits about 20 mV hyperpolarization in response to 9 s field application. Membrane potential change estimated by the pumping rate based on the synchronization modulation frequency is shown in the lower right panel. The similar trends in the upper right and lower right panels indicated that the membrane potential change is due to the pumping rate acceleration. These results demonstrate that the SM technique can effectively hyperpolarize the membrane potential of the smooth muscle cells in blood vessel quickly in ten seconds.